Knowledge Type: Clinical Articles

Prostate cancer cell usually requires androgen hormone, such as testosterone, to grow. Androgen deprivation therapy (ADT) is part of the standard protocol in the treatment of prostate cancer. It works by blocking the activity of male sex hormones such as testosterone, resulting in inhibition of cancer cell growth as well as division of the prostate cancer cells. Despite this treatment, cancer will become “castration-resistant”. Darolutamide is a non-steroidal anti-androgen that acts as an antagonist at the androgen receptor. It is indicated for non-metastatic castration-resistant prostate cancer. It is Therapeutic Goods Administration (TGA) approved (based on the Phase 3 ARAMIS Trial) but not Pharmaceutical Benefits Scheme (PBS) listed as yet. It can currently only be accessed by a compassionate supply program.

Darolutamide is available as 300mg oral tablets. The recommended daily dose is 600mg twice daily with food which is also the maximum daily dose. It is metabolised by CYP3A4. Therefore, CYP3A4 inhibitors such as itraconazole will increase the concentration of darolutamide (use with caution and monitor for drug toxicity) while drug inducers, such as rifampicin will decrease its concentration (avoid combination). Dose reduction is recommended if a patient has severe renal impairment or moderate hepatic impairment.

Most common side effects observed were fatigue, rash, pain in extremities, neutropenia, increased bilirubin levels as well as aspartate aminotransferase (AST). Central nervous system side effects were not significant given the drug’s low penetration of the blood-brain barrier. Nubeqa® is included in the Black Triangle Scheme to encourage reporting of the adverse events to help build up a full product safety profile.

Your patients will sometimes ask you about whether or not a particular medicine or supplement is permitted in sport. This might seem a trivial question, but to the person asking it is a very serious question. Sporting people stand to lose their livelihood if they make a wrong decision and take something that is banned. It is not enough to rely on the prescriber’s knowledge – they can be caught out too and come in for heavy censure and potential loss of livelihood, so check before giving something seemingly innocuous to an athlete. If you don’t know the answer, you need to know where to look to find it.

Where to look

One place to look for a quick answer is eMIMS, which can sometimes tell you what you want to know. However, it is not authoritative: eMIMS is only a secondary source.

The first authority is the World Anti-Doping Agency (WADA). It publishes the World Anti-Doping Code. The Code undergoes a major revision every few years (the latest edition takes effect on 1st January 2021) with smaller amendments in the intervening years. The Code has legal force in Australia under the same Act that established Sport Integrity Australia (SIA, previously known as the Australian Sports Anti-Doping Authority or ASADA).

WADA also publishes the Prohibited List, updated annually. This contains a comprehensive list of banned substances. Most are banned absolutely, but some are only prohibited in certain sports and/or during competitions. Beta-blockers, for example, fall into the latter category – they are banned in sports that require fine motor control, such as snooker or rifle shooting.

SIA’s website is the best place to look for information local to Australia. You should be aware that individual sports may have rules additional to those of WADA and SIA. The particular national sporting organising body should be consulted.

In the ACT, there is separate legislation that applies to ACT competitors. It works in conjunction with SIA’s powers.

Supplements

These are substances that can have amino acids, proteins, vitamins, minerals, or herbs – either separately or much more commonly in a myriad of combinations. Supplements are particularly dangerous to a sportsperson whether in the form of medication or as dietary modification. Even if the product appears to be safe, you can only be certain if the particular packet you are looking at has been independently tested. The label can lie and often does. In 2016, a survey of 67 different common products available in Australia found that 20% of them contained at least one banned substance. None of the suspect packs listed the banned substance on the packaging. Some supplements are big tins of powder with no therapeutic claims apart from vague statements like “may help to boost your immunity” – these are just Russian roulette for athletes.

Regulation

A product which makes therapeutic claims must be at least licensed by the Therapeutic Goods Administration and bear an “AUSTL” number, but even then, control is poor – there are no guarantees. If there’s an “AUSTR” number, the product is registered, not merely listed, and is certain to contain what the label says it does. Elevit® is a rare example of a vitamin and mineral supplement that is registered and has real weight behind its claims.

Consequences of poor decisions

• At the 2000 Olympics in Sydney, Romanian gymnast Andreea Raducan was prescribed a cold remedy by her team doctor. It contained pseudoephedrine, which is a banned substance. She was tested, disqualified, and lost her gold medal. The doctor lost his accreditations to the Olympics and to the International Gymnastics Federation.
• Occasionally supplements can be toxic, even lethal if used. Green tea extract has caused liver damage so severe that a liver transplant was required for the patient to survive.
• There is a substance called cardarine (aka GW501516) which improves physical performance: athletes abuse it, and WADA has banned it. Athletes who use it risk their lives, not just their careers, because it is a known potential carcinogen.
• Cassie Fien, a marathon runner, took a supplement she thought was safe: it contained the banned substance higenamine, even though the label did not say so. Her subsequent positive drug test resulted in a nine-month ban on competing.

On average, one athlete per month in Australia tests positive for a banned substance because they used a supplement. That’s one career derailed and possibly prematurely ended every month.

Although the ultimate responsibility for the substances they ingest rests with the athlete, health professionals have a duty to those in their care to give them the information they need to prevent them making a catastrophic decision.

Also known as a strawberry naevus, an infantile haemangioma is a proliferative benign tumour affecting the cutaneous blood vessels, in which the endothelial cells lining the vessels proliferate in an overgrowth manner. A haemangioma may be superficial, deep, or mixed (both superficial and deep). The pathogenesis is yet to be fully defined, but it is thought that they arise as a result of foetal hypoxia, in which endothelial progenitor cells (EPCs) responding to hypoxia cause new blood vessels to form. Usually EPCs are gone by the time a baby is born but they may still be present in premature or low birth-weight babies, leading to the development of haemangiomas. It is likely that the disappearance of EPCs as the child matures leads to the regression of haemangiomas.

Infantile haemangiomas may not be present at birth and usually develop within the first one to three weeks of life, with the vast majority (> 80%) developing on the head or neck. Initially the area may only have a few superficial blood vessels visible, but as the vessels divide and multiply the area becomes a noticeable bright strawberry red colour. The proliferation is rapid in the first three months, with growth usually slowing or stopping by five months; however, haemangiomas may continue to grow for up to 18 months in some cases. Once growth halts the haemangioma naturally starts to slowly involute and disappear, a process that may take up to 10 years in some cases. In at least half of cases involving larger ‘bulky’ haemangiomas there may not be complete regression and a scar, excess skin, or telangiectasia may remain.

In contrast, other types of birth mark, for example capillary vascular malformations (also known as port-wine stains), are present and visible at birth and are unlikely to improve without treatment.

Haemangiomas are considered the most common of the benign tumours that occur in infants. Up to 10% of neonates develop one or more infantile haemangiomas, affecting girls more commonly than boys (ratio of 2:1). In addition to gender other risk factors include prematurity, birth weight less than 1kg, multiple gestation, white skin and advanced maternal age. No genetic component has been identified for developing haemangiomas, but a family history is considered by some sources as an additional risk factor.

An infant’s GP or paediatrician should be made aware of the presence of a haemangioma, regardless of location, for assessment since the treatment of haemangioma requires specialist involvement. While some haemangiomas cause no problems to the infant and will resolve without issue, some require urgent referral (see Table 1) as they are more likely to be associated with complications and may require treatment.

Table 1. Haemangiomas that require urgent referral

Requires urgent referral to a specialist	Reason necessitating urgent referral
Haemangiomas on the face that proliferate rapidly	Close proximity to the eye, nose, lips or in the beard area can lead to obstruction or functional impairment.
Haemangiomas on the face that are segmental	May be associated with ocular, intracranial and/or cardiovascular problems.
Haemangiomas on other high-risk areas	Other areas considered high risk include the anal and genital region.
Ulcerated lesions	Areas most commonly experiencing ulcerated lesions include the lip or the nappy area. May lead to infection or scarring.
Multiple haemangiomas	Systemic involvement should be excluded since they can also develop on internal organs.

The decision to treat infantile haemangiomas is based on location, size and complexity. When deciding to treat, the risks and benefits should be carefully considered, and in many cases (particularly if a haemangioma is not on the face or in another high-risk area) treatment is not required. Treatment may be considered for haemangiomas that: are in close proximity to important structures (for example the eyes, ears, nose, or airways), become ulcerated, or pose a risk to the child’s self-esteem or social development.

Currently available treatments include medication, surgery or laser therapy. Medicines that are most commonly used include beta-blockers such as oral propranolol or topical timolol, or corticosteroids. Other potential therapies include sirolimus, vincristine, imiquimod, interferon alpha, and angiotensin-converting enzyme inhibitors, but these agents have less evidence and safety data to support their use.

Oral propranolol is considered first-line treatment for patients that require systemic therapy, but the complex mechanism of action for haemangioma resolution is yet to be fully understood. Consensus guidelines recommend that propranolol is initiated in healthy infants at a dose of 1mg/kg/day split over two doses, which can be increased to 2mg/kg/day after one week if required. In high-risk infants, for example if the infant has a low body weight or has a risk of hypoglycaemia, a lower initiation dose of 0.5mg/kg/day may be given in a setting in which the heart rate and blood glucose level may be monitored for the first three hours after initiation. Side effects that have been reported with the use of oral propranolol for this indication include hypotension, bradycardia, cold extremities, hypoglycaemia, bronchospasm, diarrhoea, and sleep disturbances. It is recommended that propranolol is administered with food, and it should be withheld if the child has a decreased food intake or if they develop an illness.

In the past, oral or intralesional corticosteroids were considered first line therapy; however, corticosteroid use has fallen out of favour in preference for propranolol. Propranolol was shown to be more efficacious when compared to corticosteroids in a 2016 meta-analysis and is considered to have a preferable safety profile. Systemic steroids may be considered for patients who are unable to use beta-blockers, such as those with bradycardia or asthma.

A systematic review and meta-analysis conducted in 2017 investigated the efficacy and adverse effects of using topical timolol preparations. Researchers found that most studies used timolol 0.5% applied topically to the area twice daily, although preparation strength varied between studies from 0.1% to 0.5%. Low participant numbers in the included studies (N = 691) resulted in an inability to draw sound conclusions regarding the comparative efficacy between the studied timolol strengths, but pooled meta-analysis for timolol 0.5% indicated a 91% resolution rate compared to 9% in patients receiving placebo or no treatment. It was found that the incidence of side effects was relatively low and that the preparations were well tolerated, however, researchers noted that this is based on a low number of participants and that participant selection bias may have affected results. Researchers concluded that the results of the analysis appear to support the use of topical timolol, but recommended that it be reserved for superficial, small, uncomplicated haemangiomas until more evidence is available.

Whilst most infantile haemangiomas are harmless and will resolve over time, it is important that infants with one or more suspected haemangiomas are referred promptly for review, specialist referral, and treatment if necessary.

On the 1^st of January 2020 abemaciclib became listed on the Pharmaceutical Benefits Scheme (PBS) for first-line treatment for non-premenopausal people newly diagnosed with hormone receptor positive, HER2-negative locally advanced or metastatic breast cancer, when taken in combination with anastrozole or letrozole. If anastrozole or letrozole is not appropriate, abemaciclib can be given in combination with fulvestrant or other endocrine therapy; however, the patient will not qualify for abemaciclib on the PBS.

Mechanism of Action

Abemaciclib is a small molecule inhibitor of cyclin-dependent kinases 4 and 6. In breast cancer, this mechanism of inhibition has shown to block progression from G1 into S phase of the cell cycle, leading to cell cycle arrest, senescence, apoptosis and subsequent suppression of tumour growth.

Clinical Trial Data

Abemaciclib indicated for women with hormone receptive positive and HER2-negative locally advanced breast cancer has been assessed in three clinical trials; MONARCH 1,2, and 3. MONARCH 2 and 3 were of particular importance as these clinical trials compared abemaciclib to placebo, in combination with fulvestrant (MONARCH 2) or aromatase inhibitors; anastrozole/letrozole (MONARCH 3). In MONARCH 2 and 3, the objective response rate and median progression-free survival were higher in the abemaciclib combination treatment arms.

Dose

The initial dose of abemaciclib is 150mg twice daily (with or without food) and is to be taken in combination with endocrine therapy (anastrozole, letrozole or fulvestrant).  If patients experience side effects, dosage reductions in 50mg increments can occur (i.e. 150mg twice daily to 100mg twice daily). However, abemaciclib should be discontinued if patients cannot tolerate 50mg twice daily.

Drug interactions

Abemaciclib is primarily metabolised in the liver by CYP3A4. Consequently, any medications which inhibit or induce CYP3A4 will affect abemaciclib drug levels. Additionally, the major active metabolites of abemaciclib inhibit the renal transporters organic cation transporter 2 (OCT2) and multidrug and extrusion toxin protein (MATE1) and MATE2-K. Consequently, medications that are substrates of these transporters could be affected by abemaciclib co-administration.

Adverse Effects

The most common adverse effects of abemaciclib include:

• Diarrhoea – onset is usually within six to eight days of commencing treatment. At the first sign of loose stools, fluids and antidiarrheal medication (e.g. loperamide) should be commenced;
• Neutropenia – onset is approximately one month after starting treatment. Blood tests should be completed at baseline and monitored regularly throughout treatment;
• Infections, interstitial lung disease and pneumonitis – monitor patients closely for pulmonary symptoms;
• Hepatotoxicity – elevations in ALT and AST can occur, monitor closely. In patients with severe hepatic impairment, dosing should be reduced to once daily;
• Venous thromboembolism;
• Nausea;
• Fatigue;
• Anaemia;
• Vomiting; and
• Hair loss.

Abemaciclib is the third cyclin-dependent kinase inhibitor to be listed on the PBS, and it is optimistic to see increased PBS options for patients with locally advanced/metastatic breast cancer.

Primary Cutaneous T-cell Lymphoma is a rare type of non-Hodgkin’s lymphoma (approximately 0.8 in 100,000 in Western countries). They are complex, heterogeneous and characterised by localisation of neoplastic T-lymphocytes to the skin. CD30 positive T-cell lymphoma encompasses anaplastic large cell lymphoma (ALCL) at the malignant end and lymphomatoid papulosis at the benign end. Borderline lesions lie somewhere in between, with overlapping clinical and histopathological features. Mycosis fungoides is the most common type of primary cutaneous T-cell lymphoma and can be co-morbid with CD30 positive T-cell lymphoma.

CD30 positive primary cutaneous T-cell lymphoma refractory to standard treatment has some evidence for systemic therapies, such as described below. However, due to the rare nature of primary cutaneous T-cell lymphoma, other randomised clinical trials are lacking. Although multi-agent cytotoxic regimens may be palliative, there is no proven survival benefit.

Treatment options for relapsed disease are limited, and this led to the study comparing brentuximab and physician’s choice from 2012 to 2015 for CD30 positive primary cutaneous T-cell lymphoma that failed at least one treatment.

Brentuximab is an anti-CD30 antibody that is conjugated to an anti-microtubule agent, monomethyl auristatin E (MMAE). The binding of brentuximab to the CD30 receptor results in the internalisation of the whole molecule to the lysosomal compartment. The monoclonal antibody is then cleaved from the MMAE through proteolytic cleavage inside the cell and results in apoptosis by interrupting the microtubule network inside the cell.

In this international, open-label, randomised, phase 3 trial brentuximab was compared with physician’s choice in patients who were previously treated with CD30 positive cutaneous T-cell lymphoma. CD30 positive patients were defined as those with greater than 10% CD30 positive cells or lymphoid infiltrate. Treatment in the physician’s choice arm was methotrexate 5 to 50mg orally ONCE per week or bexarotene 300mg/m² orally per day. Brentuximab was given at a dose of 1.8mg/kg and treatment was continued until progression or unacceptable toxicity for a maximum of 16 cycles.

The primary endpoint was an objective response for a minimum of four months (ORR4) as defined by an independent panel. All patients who finished treatment were followed every 12 weeks for a minimum of 24 months. The objective response is a more appropriate measurement of outcome than progression-free survival (PFS) in cutaneous T-cell lymphoma as PFS may still include those who are symptomatic and progress to other therapies. ORR4 was chosen as a measurement that measures not only the proportion of response but also the length of response.

The ORR4 was 56.3% vs 12.5% in favour of brentuximab over physician’s choice. This strong response was seen in both subgroups of primary cutaneous ALCL and mycosis fungoides. In all subgroups, there was an improvement in response and across all ranges of CD30 levels. Benefit was shown for all key secondary endpoints, and the median duration of response was 15.1 months.

The most common side-effect is peripheral neuropathy, which is not surprising given MMAE is an anti-microtubule agent. Nine out of 66 patients (13%) ceased brentuximab due to peripheral neuropathy. 67% of patients experienced some form of peripheral neuropathy, however, the majority were mild cases being Grade 1 or 2. Peripheral sensory neuropathy was the most common form of peripheral neuropathy seen in 45% of patients. There was also one patient whose death was attributed to brentuximab due to tumour lysis syndrome on sites of visceral lymphoma involvement.

Patients with CD30 greater than 10% were included in this trial. However, other trials have been conducted in patients with lower CD30 counts and high Sezary cell count, another exclusion criteria, and were shown to respond to treatment with brentuximab.

Pralatrexate is a potent anti-folate molecule that is designed to be efficiently internalised by the reduced folate carrier (RFC) and folylpolyglutamyl synthetase (FPGS). This causes accumulation in lymphoma cells. Upon internalisation, it inhibits dihydrofolate reductase and thereby inhibits DNA replication and cell division.

The PROPEL study treated patients with peripheral T Cell Lymphoma (PTCL) with 30mg/m2/week every six out of seven weeks. Patients included had been treated with at least one treatment and progressed after treatment. Treatment was continued until disease progression, unacceptable toxicity or stopped at the physician’s discretion.

The primary endpoint for PROPEL was an objective response (ORR), and a secondary outcome was the length of response. ORR was assessed by central review.

One hundred eleven patients received treatment, and 29% had an ORR, the primary outcome for PROPEL. 11% had complete remission, and 19% had stable disease. For patients who did not respond to their most recent therapy, 25% of those patients had a response, and 24% of patients treated with prior methotrexate, a drug with a very similar mechanism of action had a response.

The median duration of response was 10.1 months, and median overall survival was 14.5 months.

Mucositis is the most common reason for dose reduction with pralatrexate (23% of patients). Other reasons in PROPEL included abnormal liver function tests (LFTs), thrombocytopenia, fatigue, Herpes Zoster, Neutropenia and pruritic rash.

Grade 3 or 4 adverse reactions included thrombocytopenia, mucositis and neutropenia and 5% of patients experienced a case of febrile neutropenia. One death was potentially attributed due to pralatrexate, a cardiopulmonary arrest while being hospitalised with mucositis and febrile neutropenia.

Four patients that received autologous stem-cell transplantation (ASCT) post-pralatrexate remained in remission at the time of the article being published, and the authors suggested this is a potential bridge to stem cell transplantation for pralatrexate.

As stated above, mucositis is the most common troublesome side-effect with pralatrexate treatment. A study gave folinic acid 25mg three times daily for two days, starting 24 hours after pralatrexate treatment to look at whether this helps with mucositis associated with pralatrexate. The primary endpoint was Grade 2 or greater mucositis in cycle one of pralatrexate treatment (six doses). At the time of analysis, all 30 patients met the primary endpoint. This is now included as standard treatment for patients receiving pralatrexate treatment. Another study has shown giving five days of leucovorin 25mg every six hours, stopping at a minimum 48 hours prior to the next pralatrexate dose ameliorated mucositis in patients receiving pralatrexate, and it has been reported as standard practice in one centre to give leucovorin 15mg four times daily for every day except the day before, day of, and the day after chemotherapy. In patients with mucositis despite two days of leucovorin, extended leucovorin treatment could potentially be an option.

Refractory primary cutaneous T-cell lymphoma, as discussed, is a disease with very poor prognosis and these treatment options are now available in this difficult to treat population. Mucositis is no longer as debilitating as it was with pralatrexate, given the standard prophylactic treatment with two days of leucovorin or at the physician’s discretion even a longer period of leucovorin treatment to prevent mucositis.

“Gliflozins”, or sodium-glucose co-transporter 2 (SGLT2) inhibitors, are the newest class of oral anti-diabetic medications. Dapagliflozin was the first agent in this class to be approved for use in diabetes in 2012 (by both the European Medicines Agency and the Therapeutic Goods Administration), with empagliflozin and ertugliflozin being approved later – in 2014 and 2018 respectively. Gliflozins exert their therapeutic effect by inhibiting the sodium-glucose co-transporter 2 in the nephron, thus reducing the reabsorption of glucose. They are approved to treat type 2 diabetes mellitus (T2DM).

T2DM is a known risk factor for heart failure (HF), particularly those with longstanding diabetes, poor glycaemic control, insulin treatment or microvascular complications such as nephropathy.

In 2015 a randomised, double-blind, placebo-controlled clinical trial was initiated to investigate the cardiovascular outcomes of diabetic patients treated with empagliflozin. The trial followed 7,020 patients across 42 countries and measured a composite of death from cardiovascular causes as well as nonfatal myocardial infarction (MI) and stroke. The empagliflozin group was found to have a significantly lower incidence of primary outcomes (10.5% vs 12.1%) as well as all-cause mortality (HR, 0.68; 95% CI, 0.57 to 0.82, P<0.001) and heart failure (HR, 0.65; 95% CI, 0.50 to 0.85; P=0.002). Although this trial was designed merely to show the cardiovascular safety of gliflozins, these surprising results were in fact the first incidence of a glucose-lowering agent showing clear superiority to placebo when measuring primary CVD (cardiovascular disease) endpoints.

If these results were not remarkable enough, the latency in improved clinical outcomes is surprisingly short, indicating that a reduction in blood-glucose level (BGL) is unlikely to be implicated. The median treatment period was only 2.6 years with a difference in primary outcome becoming evident approximately three months after initiating empagliflozin. In contrast, “Even when a formal multifactorial intervention is undertaken, such as in the Intensified Multifactorial Intervention in Patients With Type 2 Diabetes and Microalbuminuria (STENO-2) trial (ie, renin-angiotensin system blockers, aspirin, and lipid-lowering agents), cardiovascular protection is not observed for several years”.

It is also interesting to note that the treatment arm of the trial did not experience a reduction in ischemic events (MI/stroke), implying that perhaps the 35% reduction in hospitalisations due to HF may be a decisive factor. A paper published in February 2020 in BBA – Molecular Basis for Disease by researchers from a German university hospital reviewed current hypotheses on the mechanisms by which gliflozins may be of benefit in HF. Whilst the mechanism(s) is/are not fully understood, the researchers suggest it is likely to be pleiotropic (affecting genes that code for multiple phenotypes), possibly involving metabolism and electromechanical coupling in the myocardium.

In March 2020 the American College of Cardiology published results of a trial investigating the protective effect of dapagliflozin in patients with HF. This was a randomised placebo-controlled trial with 4,744 participants with a mean age of 66 years. Similar to the empagliflozin trial, this study found that dapagliflozin reduced cardiovascular deaths and HF events compared to placebo. These results were independent of diabetes status (T1DM patients were excluded), age, background health or other medications.

Finally, the CANVAS trial – investigating canagliflozin (not marketed in Australia) – and a further meta-analysis of all three trials, added further weight to the class-effect of gliflozins reducing the risk of hospitalisations due to HF in patients with and without established atherosclerotic CVD. The meta-analysis found the reduced hospitalisation for HF and CVD mortality rate to be 23% and to have an even greater protective effect in those with reduced eGFR (estimated glomerular filtration rate). Conversely, the risk reduction for major adverse cardiovascular events was found to be only modest (11%), and this was largely observed in those with established atherosclerotic CVD (ASCVD). However, the more recent CREDENCE trial, looking at canagliflozin in those with albuminuric chronic kidney disease (CKD), provided more robust evidence of the potential benefits of gliflozins with atherothrombotic events – major adverse cardiovascular events (MACE) HR = 0.8 (0.67-0.95)⁵.

Upon reanalysis of the data from DECLARE-TIMI 58, researchers found similar benefits for ASCVD patients taking dapagliflozin – MACE HR 0.84 (95% CI, 0.72-0.99) – but only in patients with prior MI. The effect of reduced ejection fraction was also re-analysed from this data, showing increased benefits of dapagliflozin in those with reduced ejection fraction. The following table summarises the differences.

Table 1. (Adapted from Verma S, et al.)

Outcome	HFrEF	HF without rEF
CV Death	↓45%	–
HF Hospitalisations	↓36%	↓24%
All-Cause Mortality	↓41%	–

(CV Death = deaths from cardiovascular disease, rEF = reduced ejection fraction)

It would, therefore, appear that SGLT2-inhibitors (gliflozins) are rapidly emerging as a novel treatment for heart failure, including heart failure with preserved left ventricular ejection fraction.

Introduction:

By July 23rd, 2020 there were 15,117,078 SARS-CoV-2 infections, resulting in 620,033 deaths.

Prompted by the unrelenting progress of the pandemic, and based upon new research from Beigel et al., the Therapeutic Goods Administration (TGA) announced that remdesivir (“Veklury”, Gilead Sciences Pty Ltd) had received provisional approval as the first treatment option for COVID-19, caused by SARS-CoV-19 (severe acute respiratory syndrome coronavirus).  Approval for use is currently restricted to adults and adolescent patients with severe COVID-19 symptoms who have been hospitalised.

Remdesivir (GS-5734), is a nucleoside analogue pro-drug. A nucleoside is comprised of a nitrogen base plus the sugar, ribose, but without the phosphate group (discussed below).

Remdesivir antiviral activity:

SARS-CoV-19 is a member of the coronavirus family. It is an enveloped virus with a positive-sense, single-stranded RNA genome that infects animal species and humans. Other members of this viral family are those responsible for the common cold, severe acute respiratory syndrome coronavirus (SARS) and Middle East respiratory syndrome-related coronavirus (MERS).

In vitro, remdesivir inhibits all human and animal coronaviruses thus far tested, including SARS-CoV-2. It has also shown to have antiviral properties and clinical benefits in animal models of SARS-CoV-1 and MERS infections.

Mechanisms of action of remdesivir:

To understand the mechanism of action of remdesivir, a review of the structural architecture of RNA is warranted.

Briefly, all RNA viruses use RNA-dependent RNA polymerase (RdRP) to carry out the biosynthesis of a new RNA strand from an RNA template.

Like all RNA viruses, SARS CoV-2 RNA is comprised of four nitrogen-containing bases – uracil (U), cytosine (C), adenine (A) and guanine (A). These bases are joined to ribose, a sugar molecule, and a phosphate group, to form what is known as a nucleotide. (Figure 1)

A nucleotide is the foundational building block of nucleic acids. If the phosphate group is absent, the structure is called a nucleoside.

Figure 1. (Courtesy: National Human Genome Research Institute)

During normal viral reproduction, adenine pairs with uracil and cytosine pairs with guanine. This replication is performed by RNA-dependent RNA polymerase (RdRp).  As noted earlier, it is the role of RdRp to match the correct corresponding base, to form the correct base pair. (Figure 2)

Figure 2. (Courtesy: OpenStax)

There are three methods by which remdesivir blocks RNA viral replication.

The primary mechanism of action of remdesivir (RDV), given as the pro-drug RDV triphosphate (RDV-TP), is to substitute itself for the adenine nucleotide known as adenosine triphosphate (ATP), to which it is structurally similar. (see figure 3).

Figure 3 (Courtesy: Gordon et al., J Biol Chem)

RDV then binds to uracil, which results in termination of viral replication due to the false base in the replication chain.

The second important mechanism for RDV is a variation to the carbon-nitrogen (CN) group attached to ribose, the RNA relevant sugar.

This variation means that as RDV is included into the replicating RNA chain, the presence of the CN group causes the chain to become misshaped. This distortion means that only three more nucleotides can be added before viral RNA synthesis is terminated at position i+3, where i is the insertion point of remdesivir in the new RNA chain.

The third important mechanism of action flows from the second. Because three extra nucleotides have been inserted by RdRp into the new RNA strand after the insertion of the RDV “look-alike” base, the presence of RDV may now be protected from removal by the coronavirus’s exonuclease enzyme.

Exonuclease is a feature of coronaviruses which act to recognise and remove (clip out) artificial nucleotides. It is the virus’ proof-reading mechanism.  The chemical bond changes mean that remdesivir cannot be excised, resulting in chain propagation with delayed but eventual termination of RNA synthesis. Because RDV has been added into the RNA chain replication, it has stealthily avoided “the proofreading subunit required to safeguard coronavirus replication fidelity.”

Early study “failure” with remdesivir used in treating Ebola.

In trials against Ebola virus in the Democratic Republic of the Congo in 2018, remdesivir was found to be inferior to other comparators in terms of patient mortality and was withdrawn from the study. It was concluded that it was a failure, due to a higher mortality rate from Ebola in recipients when compared to than other trial drugs.

However, the conclusion that it is an ineffective antiviral drug is erroneous. The explanation for RDVs poor performance against Ebola virus but success against SAR-CoV-2 is due to the variation in binding strengths of RDV and adenosine in the two viruses. RDV binds four times less strongly to the Ebola polymerase – the enzyme that makes RNA copies – than does the adenine containing nucleotide, adenosine triphosphate (ATP).

Thus, in the Ebola virus, due to a higher binding efficacy to Ebola polymerase, adenosine takes its correct position and binds to uracil. Consequently, viral replication is not significantly impeded.

However, in COVID-19 patients, RDV binds four times more strongly to SARS-COV-19 polymerase, resulting in the exclusion of the adenosine triphosphate, the inclusion of RDV in its place, and the base pairing of remdesivir – not adenine – to uracil. Consequently, SARS-COV-19 replication is terminated.

Remdesivir study in Hubei.

Patients in this study, conducted from Feb 6, 2020, and March 12, 2020 were randomly assigned in a 2:1 ratio to remdesivir IV (200 mg on day 1, then 100 mg on days 2–10 as a single daily infusion) or a placebo of the same volume (n=237).  Both RDV and placebo were given for ten days.

Remdesivir use was not associated with a difference in time to clinical improvement (hazard ratio 1·23 [95% CI 0·87–1·75]), and there was no significant difference in time to clinical improvement between RDV or placebo patients. RDV use was terminated early because of adverse events.

A therapy confounder in this study was that patients were permitted concomitant use of lopinavir–ritonavir, interferons, and corticosteroids.

Clinical support for remdesivir use.

On May 22, 2020, Beigel and co-workers published the results of a double-blind, randomised, placebo-controlled trial of remdesivir (IV) in adults hospitalised with Covid-19 with evidence of lower respiratory tract involvement.

Patients received either remdesivir (200 mg loading dose on day 1, followed by 100 mg daily for up to 9 additional days) or placebo for up to 10 days. The primary outcome was the time to recovery, defined by either discharge from the hospital or hospitalisation for infection-control purposes only.

Preliminary results from the 1059 patients (538 assigned to remdesivir and 521 to placebo) with data available after randomisation indicated that those who received remdesivir had a median recovery time of 11 days (95% CI, 9 -12), as compared with 15 days (95% CI, 13 to 19) in those who received placebo (rate ratio for recovery, 1.32; 95% CI, 1.12 to 1.55; P<0.001).

At 14 days, the Kaplan-Meier estimates of mortality were 7.1% with remdesivir and 11.9% for placebo (hazard ratio for death, 0.70; 95% CI, 0.47 to 1.04).

This reduction in mortality was not clinically significant.

Serious adverse drug events were reported in 114 of 541 patients in the RDV group (21.1%) and 141 of   522 patients in the placebo group (27.0%).

The authors concluded that RDV was superior to placebo in shortening hospitalised COVID-19 adults recovery time who had evidence of lower respiratory tract infection.

Criticisms of the trial:

Correspondents to the New England Journal of Medicine have raised several concerns with the study.

• Samantha Gillenwater, M.D. noted that patients with Covid-19–related respiratory disease, the median time to randomisation was nine days, at which stage the illness was advanced. A more instructive result may have been obtained if RDV had been commenced earlier.
• James H. McMahon, Ph.D considered that RDV may have been given too late to many patients, since the median time to onset of acute respiratory distress syndrome (ARDS) is 8.0 days.
• Julián Olalla, M.D., Ph.D. asked what other medications (hydroxychloroquine, lopinavir–ritonavir, azithromycin, or tocilizumab) were allowed if the local protocols permitted their use.

In reply, Dr Beigel noted that the report was interim data and that further data analysis will address these and other issues raised by colleagues.

Conclusion:

In mid-May 2020 it was estimated that a vaccine would not be out of phase 3 trials until mid-2021. Thus, early use of hydroxychloroquine with zinc and azithromycin, remdesivir or tocilizumab appeared to be the best clinical measures available. However, in late July 2020, at least four research centres reported promising results, with a vaccine now possible in mid-2021. These vaccine candidates include:

• The University of Queensland protein spike clamp,
• Novavax and its trial vaccine, designed to trigger an immune response by imitating the SARS-CoV-2 spike protein,
• The University of Oxford trial vaccine named ChAdOx1 nCoV-19 which was tested in a joint phase 1 and 2 trial of 1,077 people aged 18-55, and
• Moderna have developed an mRNA vaccine which encodes the SARS-CoV-2 spike (S) glycoprotein. The S glycoprotein facilitates host cell attachment and is essential to viral entry into the host cell. Volunteers produced both antibodies against SARS-CoV-2, and immune T cells to the virus. Phase 3 trials begin in the northern summer of 2020.

Unsafe injection practices can cause infectious disease in individual patients and may also lead to outbreaks within a facility. In 2015-2016, the Australian Commission on Safety and Quality in Health Care reported that hospital-acquired infections affected one in 74 hospitalisations in the public sector. Hospital-acquired infections have a significant impact on patient morbidity and mortality, as well as healthcare costs. A patient’s mortality risk is thought to be at least three times higher if they acquire an infection in hospital.

Infections related to the contamination of vials and ampoules can include life-threatening conditions such as bloodstream infections, meningitis, and epidural abscesses. Ampoules and vials can be classified as either ‘multi-dose’ or ‘single-dose’. A multi-dose vial contains more than one dose of medication and is formulated with an antimicrobial preservative. Conversely, a single-dose vial is typically formulated without a preservative and is intended for use in a single patient on a single occasion.

Single-dose vials

Preservative-free preparations can easily become contaminated. If a single-dose vial is contaminated and then reused for more than one patient, the result may be an outbreak in multiple patients rather than just a single case of hospital-acquired infection. However, it is worth noting that the preservatives used in parenteral products do not offer sufficient protection against non-bacterial pathogens such as viruses, protozoa, and prions. For this reason, it is imperative that strict aseptic technique is practised for all injections regardless of whether the product contains a preservative or not.

Single-dose vials or pre-filled syringes are preferred to multi-dose vials to reduce the risks associated with microbial contamination. While single-dose products are considered safer, this is only true if they are used in accordance with best practice. Best practice dictates that a single-dose vial is only entered once and any unused contents discarded immediately afterwards. If multiple entries into a single-dose vial are considered appropriate by the healthcare professional, it must only occur if allowed under hospital policy.

In this current environment, drug shortages may also present an issue. When a critical medicine is in short supply, the concept of drug wastage may assume increased significance. However, the inappropriate reuse of single-dose vials can create additional problems. A long-term drug shortage of bupivacaine was determined to be a factor in an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in the United States. Clinic staff reused single-dose vials for multiple patients in an attempt to conserve their limited stock. Many of these patients developed infections with an identical strain of MRSA that required hospitalisation, antibiotic therapy, and debridement. In the case of a critical drug shortage, hospital policy will determine the most appropriate course of action.

There is one circumstance where the reuse of single-dose vials is deemed acceptable by the Therapeutic Goods Administration (TGA). However, for these purposes, the manipulation of the dose form is considered pharmaceutical compounding. These processes should occur under unidirectional airflow (Grade A environment) in compliance with Good Manufacturing Practice, i.e. the TGA guidelines are not applicable for use in the ward environment.

Multi-dose vials

While single-dose products are generally preferred, there may be cases where an injectable product is only available in a multi-dose vial. The National Health and Medical Research Guidelines advocate the following steps to reduce the risk of infectious disease transmission when using multi-dose vials:

• Restrict the vial to single patient use wherever possible;
• Establish a separate secure area designated for the placement of these medications away from any work area;
• Strict compliance with the manufacturer’s recommendations regarding storage, use within a specified time, and expiry date. Some preservatives are actually less effective at lower temperatures, so refrigeration is not recommended for all products;
• Use a sterile needle and syringe to draw up the required dose from the vial or ampoule on every occasion;
• Use a sterile needle to draw up all the contents of the container into individual syringes before administering to patients;
• Only store the current patient’s medication in the immediate working environment
• Discard any open ampoule(s) at the end of each procedure; and
• Discard product if product sterility or integrity is compromised or questionable.

Summary

Microbial contamination can occur during the preparation and administration of any medicine from a multi-dose or single-dose vial. Therefore, strict attention to aseptic technique is essential whenever a medication is prepared or administered parenterally. It is recommended that medication vials and ampoules be discarded if sterility is compromised or cannot be confirmed.

Diabetes mellitus is a chronic condition in which the body loses its ability to produce insulin, or begins to produce insulin less efficiently, resulting in blood glucose levels that are too high.

Insulin is a hormone produced by beta cells in the pancreas. It facilitates the uptake of glucose from the bloodstream into the cells. Insulin is essential to prevent the accumulation of glucose in the circulation, which can cause complications such as peripheral neuropathy (nerve damage) and diabetic nephropathy (kidney impairment).

Type 1 diabetes mellitus (T1DM) develops when the pancreas stops producing insulin due to damaged or destroyed beta cells. Without insulin, glucose cannot move from the bloodstream into the cells. People with T1DM are reliant on insulin injections.

Type 2 diabetes mellitus (T2DM) develops when the pancreas cannot make sufficient insulin and/or the body doesn’t respond adequately to the insulin that is produced (insulin resistance). People with T2DM may require insulin injections as the disease progresses.

 

Types of Insulin

There are five types of insulin available in Australia, categorised based on their onset and duration of action.

Rapid-acting insulin
Rapid-acting insulin starts working between 2.5 – 20 minutes after injection. Its action peaks between one and three hours post-injection and can last up to five hours. This type of insulin is used to facilitate the uptake of glucose after eating as this mimics the body’s natural insulin response. It is injected immediately before meals.

The three rapid-acting insulins available in Australia are:

• NovoRapid® and Fiasp® (insulin aspart)
• Humalog® (insulin lispro)
• Apidra® (insulin glulisine)

Short-acting Insulin

Short and rapid-acting insulins are often referred to as ‘bolus’ insulins due to their shorter duration of action compared to intermediate and long-acting insulins.

Short-acting insulins begin to work within 30 minutes of injection, so need to be administered approximately 30 minutes prior to meals. They reach their maximum effect 2-5 hours later and last for 6-8 hours.

Short-acting insulins available in Australia include:

• Actrapid® (insulin neutral)
• Humulin® R (insulin neutral)

Intermediate-acting Insulin

Intermediate and long-acting insulins are often referred to as ‘basal’ insulins due to their sustained release and longer duration of action.

Intermediate-acting insulins have a cloudy appearance and need to be mixed well prior to administration (normally rolled in the hand).

These insulins begin to work around 60-90 minutes after injection, peak between 4 to 12 hours later and last for between 16 and 24 hours.

Intermediate-acting insulins available in Australia include:

• Humulin NPH® (a human isophane insulin)
• Protaphane® (a human isophane insulin)

Long-acting insulin

Long-acting insulins produce a slow, steady release with no apparent peak in action. They last between 18 and 24 hours and can be administered once or twice daily.

Long-acting insulins available in Australia include:

• Levemir® (insulin detemir)
• Tresiba® (insulin degludec)
• Optisulin® (insulin glargine 100iu/mL) *As of July 2020 Lantus® was discontinued and replaced with Optisulin® (insulin glargine 100iu/mL)
• Toujeo® (insulin glargine 300iu/mL)

It is very important to note the difference in concentration between Optisulin® and Toujeo®, as they are both insulin glargine. They are not interchangeable.

Due to the high risk of error associated with the prescribing and administering of insulin, it is required that insulins are prescribed using their brand names; this reduces the risk of accidentally administering a three times stronger insulin glargine than was intended.

 

Figure 1: Duration of action of different insulin classes (Image by Peters, licensed under CC BY 3.0)

Mixed Insulin

Mixed insulins contain a pre-mixed combination of either very rapid-acting or short-acting insulin, together with intermediate-acting insulin.

The mixed insulins currently available in Australia include:

• Rapid-acting with intermediate-acting insulin:
  • NovoMix® 30 (30% rapid, 70% intermediate protaphane)
  • Humalog® Mix 25 (25% rapid, 75% intermediate Humulin® NPH)
  • Humalog® Mix 50 (50% rapid, 50% intermediate Humulin® NPH)
• Short-acting and intermediate-acting insulin:
  • Mixtard® 30/70 (30% short, 70% intermediate protaphane)
  • Mixtard® 50/50 (50% short, 50% intermediate protaphane)
  • Humulin® 30/70 (30% short, 70% intermediate Humulin® NPH)
• Rapid-acting and long-acting insulin:
  • Ryzodeg® 30/70 (30% rapid, 70% long-acting degludec)

 

Basal Bolus Insulin Dosing

Basal bolus insulin dosing is designed to reflect the activity of endogenous insulin i.e. the availability of small amounts of insulin throughout the day, with peaks released in response to meals.

 

Sliding Scale Insulin Dosing

Sliding scale insulin dosing is often used in the hospital setting. It involves variable bolus doses of rapid-acting insulin based on pre-meal blood glucose levels. Basal insulin doses remain unchanged.

Sliding scale insulin regimens are not common outside of the acute setting, however some people do use them to enable tight control of blood glucose levels.

 

High Risk

Insulin is considered a high-risk medication due to its ability to cause severe complications if administered incorrectly (intravenous or intramuscular instead of subcutaneously) or in the incorrect dose (mL instead of units) or at the wrong time. Such complications include hypoglycaemia (which can lead to loss of consciousness and death), hyperglycaemia, and diabetic ketoacidosis.

Introduction

By June 15^th 2020, 7,997,084 people were infected with SARS-CoV-2, and 435,662 had died. The world economic loss is estimated to be at least $1 trillion. In response, multiple vaccine trials are underway, but none are expected to be out of phase 3 trials until mid-2021.

This delay has necessitated the reassignment of several drugs from their original treatment purpose so as to rebuild the antiviral armamentarium. One of these redirected drugs is hydroxychloroquine (HCQ), currently approved in Australia for discoid and systemic lupus erythematous, rheumatoid arthritis and the suppression and treatment of malaria.

Early trials with HCQ were equivocal at best, forcing clinicians to balance the possibility of clinical benefit against the cardiotoxic effects in vulnerable patients with multiple comorbidities.

In mid-May 2020, three significant papers were released which add more certainty to the use of HCQ, or its precursor, chloroquine (CQ) in COVID-19 (C-19) patients.

On May 22^nd 2020, in The Lancet, Mehra and co-workers reported the results of an international, observational registry analysis involving the use of chloroquine or hydroxychloroquine with or without a macrolide (azithromycin or clarithromycin) between 20 December 2019 and 14 April 2020, in COVID-19 patients across 671 hospitals. There were 96,032 patients in the study. Of these, 1868 received chloroquine only, 3783 received chloroquine with a macrolide, 3016 received hydroxychloroquine only, and 6221 received hydroxychloroquine with a macrolide. There were 81,144 patients in the control group.

The mean daily doses of the various drug regimens were: chloroquine alone – 765mg; hydroxychloroquine alone – 596mg, chloroquine with a macrolide – 790mg; and hydroxychloroquine with a macrolide, 597mg.

After controlling for confounders, the researchers reported that the mortality in the control group was 9·3%, in the hydroxychloroquine group it was 18·0%, in the hydroxychloroquine plus macrolide group it was 23·8%, in the chloroquine alone group it was 16·4%, and in the chloroquine with a macrolide cohort is was 22·2%.  Each treatment modality was independently associated with an increased risk of in-hospital mortality.

Commenting on the Lancet study, Dr Josh Davis of the Doherty Institute and principal investigator of the ASCOT (hydroxychloroquine) study planned by the Institute noted that patients in the Lancet paper who received HCQ  “ … had a higher risk of death at baseline than those who didn’t. They were sicker and they had more comorbidities. That alone could potentially explain the higher risk of death. The only way of knowing whether that’s true or not is to do a randomised trial.”

This concern is well-founded because the co-administration of CQ/HCQ and a macrolide is known to cause an increased corrected QT interval. A prolonged QT interval (the time required for the ventricles to depolarise and repolarise) can precipitate ventricular arrhythmias such as torsades de pointes, which can spiral into ventricular fibrillation.

The Subsequent Controversy

On 23 May 2020, one day after publication of the Mehra paper, the World Health Organization (WHO) paused patient recruitment into the hydroxychloroquine arm of the SOLIDARITY trial, citing safety issues with HCQ that were highlighted by Mehra et al.

The SOLIDARITY study is an adaptive, randomised, open-label, controlled clinical trial, in collaboration with countries around the world through the World Health Organization.

Subjects will be randomised to receive either standard-of-care products or the study medication plus standard of care, while being hospitalised for COVID-19.

Participants will be randomised to one of the following groups:

1. Lopinavir/ritonavir 400mg/100mg orally twice daily for 14 day plus local standard care, OR
2. Hydroxychloroquine 800mg twice daily for 1 day then 400mg twice daily for 10 days plus local standard care, OR
3. Remdesivir 200mg IV on day 1, followed by 100mg IV daily infusion for 9 days plus local standard care, OR
4.  Lopinavir + ritonavir (orally twice daily for 14 days) plus interferon-beta (daily injection for 6 days). OR only
5. Local standard support care.

“The patients will be followed up for the entire length of their hospital stay. Death from any cause will be recorded and this will be the main result used to determine whether a drug is effective. Length of hospital stay and time to first receiving ventilation (or intensive care) will also be recorded and used to determine the drug’s effectiveness.”

By 28 May 2020, there was a swift international response to the Lancet study, with 201 scientists co-signing an open letter to the study authors and Mr Richard Horton, Editor of The Lancet. They cited ten concerns including the non-release of data source codes, no ethics committee review, mean daily doses of hydroxychloroquine that are 100mg higher than FDA (US Food and Drug Administration) recommendations, inadequate allowance for confounders, and more technically, “the tight 95% confidence intervals reported for the hazard ratios appear inconsistent with the data. For instance, for the Australian data this would imply about double the numbers of recorded deaths as were reported in the paper.”  The authors also denied a request for information on the contributing study centres.

On 29 May, the authors published a correction pertaining to the countries of origin for some of the data. They noted: “the numbers of participants from Asia and Australia should have been 8101 (8·4%) and 63 (0·1%), respectively. One hospital self-designated as belonging to the Australasia continental designation should have been assigned to the Asian continental designation…  The unadjusted raw summary data are now included. There have been no changes to the findings of the paper. These corrections have been made to the online version as of May 29, 2020, and will be made to the printed version.”

On 3 June 2020, the Editor of The Lancet issued an Expression of Concern letter, due to serious questions pertaining to the integrity of the data supplied to the researchers by Surgisphere, a company started by Dr Sapan Desai, one of the authors of the Mehra paper.

On the same day the Director-General of WHO announced that on the basis of the available mortality data, the Executive Group of the Solidarity Trial had agreed to the continuation of all arms of the Solidarity Trial, including the hydroxychloroquine arm, as there was “no reasons to modify the trial protocol”.

Finally, on 4 June 2020, the Mehra paper was withdrawn by three of the authors. In the notification published by The Lancet it was stated the authors “… were unable to complete an independent audit of the data underpinning their analysis. As a result, they have concluded that they “can no longer vouch for the veracity of the primary data sources.” The Lancet takes issues of scientific integrity extremely seriously, and there are many outstanding questions about Surgisphere and the data that were allegedly included in this study.”

In a further twist to the SOLIDARITY trial, on June 17^th the WHO announced that they were reversing the decision to reinstall the HCQ arm of the trial, and were cancelling further enrolment of patients in this arm.

The decision was predicated “on evidence from the Solidarity trial, UK’s Recovery trial and a Cochrane review of other evidence on hydroxychloroquine.

Data from Solidarity (including the French Discovery trial data) and the recently announced results from the UK’s Recovery trial both showed that hydroxychloroquine does not result in the reduction of mortality of hospitalised COVID-19 patients, when compared with standard of care.”

Patients already taking HCQ will either complete their course or stop at the discretion of the supervising physician.

“This decision applies only to the conduct of the Solidarity trial and does not apply to the use or evaluation of hydroxychloroquine in pre or post-exposure prophylaxis in patients exposed to COVID-19.”

Mahévas research

On May 22^nd, 2020, Mahévas and others (BMJ)  published the results of a comparative observational study of patients (n = 181) hospitalised between March 12-31, 2020. The study cohort was aged 18-80 years with documented SARS-CoV-2 pneumonia who required oxygen but not intensive care (IC).

The treatment group (n=84) received HCQ 600mg per day within 48 hours of admission, another eight patients received HCQ more than 48 after admission, and the control group (n = 89) did not receive HCQ.  The authors concluded that the use of HCQ in COVID-19 patients admitted to hospital requiring oxygen was not supported by the evidence.

Brian J Lipworth, Professor of Pulmonology (Scottish Centre for Respiratory Research, Ninewells Hospital and Medical School) noted that 85% of patients in this study who were given HCQ had evidence of the cytokine storm because their C-reactive protein (CRP) levels were greater than 40mg/L on admission. A CRP higher than 42mg/l on admission is predictive of a poor outcome.

Hence, there was no clinical merit in treating 85% of these patients with HCQ – they were already in the storm phase. The putative mechanisms of action of HCQ-only therapy include interference with viral binding to the angiotensin-converting enzyme II (ACE2) pulmonary receptor, thus reducing viral-cell membrane fusion, and increasing intracellular pH, thereby reducing viral replication.

The presence of the cytokine storm of interleukin-6 (IL-6) means that HCQ use is clinically too late. Only drugs such as tocilizumab, an IL-6 receptor blocker, have clinical justification at this point in the disease progress.

Carlucci research

The third paper in May 2020 was by Carlucci and co-workers who conducted an observational study on patients hospitalised at four New York hospitals between March 2^nd 2020 and April 5^th 2020, using the triple therapy of hydroxychloroquine (HCQ), azithromycin (AZM) and zinc sulfate (Zn) compared to HCQ plus AZM only use (pre-print, not yet peer-reviewed).

In the triple therapy arm, 411 patients had received hydroxychloroquine 400mg as a loading dose, then 200mg twice a day for five days, zinc sulfate 220mg (containing 50mg elemental zinc) twice daily and azithromycin 500mg daily.

In the comparator arm, 521 patients took HCQ plus AZM only, at the same treatment level. All patients received usual supportive care.

Univariate analyses revealed that zinc sulfate increased the frequency of discharges home, and decreased ventilation need, ICU admissions, mortality or transfer to hospice for patients who were never admitted to the ICU.

After adjusting for the time at which zinc sulfate was added, there remained a significant increased frequency of being discharged home, a reduction in mortality and a reduction in hospice transfer.

There are several caveats to note. First, this study is still in the pre-peer review stage. Second, it was, like those of Mahevas and Mehra, a retrospective, observational study, leading to many potential confounders influencing the results. Carlucci noted the following:

1. There was uncertainty as to when each medication was given (as distinct from when it was charted);
2. The time when each group commenced their therapy may have differed;
3. They were uncertain if the observed added benefit of zinc sulfate to hydroxychloroquine and azithromycin on mortality would have been seen in patients who took zinc sulfate alone or in combination with just one of those medications;
4. This study should not be used to guide clinical practice; and
5. The point in clinical disease status at which patients received those medications could have differed between our two groups.

The difference in the S and R forms of hydroxychloroquine

In a pre-print paper (not yet certified by peer review), Guanguan Li and co-workers have reported that in all clinical trials, chloroquine diphosphate or hydroxychloroquine sulfate have invariably been used. These formulae are a 50/50 racemic mixture of the R- and S- forms. However, their laboratory tests have shown that there are stereoselective differences in the respective potencies of the R- and S-enantiomer for both chloroquine and hydroxychloroquine against live SARS-CoV-2.

“S-chloroquine (S-CQ) and S-hydroxychloroquine (S-HCQ) were found to be 27% and 60% more active against SARS-CoV-2, as compared to R-CQ and R-HCQ, respectively.”

Added to this is the knowledge that “S-chloroquine seems to be less toxic than the R-chloroquine.” By extension at least, it is reasonable to conclude that S-hydroxychloroquine is less toxic than R-hydroxychloroquine, though clinical trials would need to verify this assumption.

Zinc, immune function and antiviral properties

This study poses an interesting clinical question – why was there a benefit in the zinc arm of the review?

Age is a significant factor contributing to C-19 mortality. A Chinese study (n =72,314) reported that whilst the overall mortality rate was 2.3%, the rate increased proportionally with age reaching 8% in those aged 70–79 years and 14.8% in those ≥80 years old.

One possible contributing factor to the age-related death rate is evidence showing a decline in immune function with advancing years, known as immunosenescence, with studies suggesting an impaired T-cell function against pathogens. Zinc is a contributor to functional immune capacity, with a deficiency causing a rapid reduction in innate and acquired immunity. Hence zinc is considered an essential antiviral micronutrient.

The evidence points to zinc’s antagonistic role in viral transcription. Replication of all positive-strand RNA viruses, such as SARS-CoV and SARS-CoV-2, require membrane-embedded RNA-dependent RNA polymerase (RdRp). This enzyme is at the core of the viral RNA replication machinery.  RdRp catalyses the replication of RNA from RNA templates.

Hence the importance of research by te Velthuis and co-workers who have shown that zinc inhibited SARS-CoV RdRp elongation. When compared to alternate metal ions such as cobalt or calcium, zinc was the most effective inhibitor. Zinc caused a 3-4 fold reduction RNA binding to the assay template.

Figure 1. Increasing zinc (Zn²⁺) concentration causes a decreasing level of RNA1, due to declining RdRp activity (from te Velthuis et al.)

However, it is clinically challenging to achieve an antiviral intracellular concentration of zinc because it is bound to metallothioneins.

The answer to increasing the intracellular zinc levels is to use an ionophore, a chemical species that carries ions across a cell membrane before releasing the species into the cytoplasm. Te Velthuis achieved RdRp inhibitory levels of zinc by using pyrithione (PT) as the ionophore – Carlucci used hydroxychloroquine.

It is important to note that te Velthuis tested zinc against SARS-CoV, whereas Carlucci tested it against SARS-CoV-2, another member of the coronavirus family. Because the amino acid sequence identity between SARS-CoV and SARS-CoV-2 S-proteins is 76.47%, it is clear that these two viruses are genetically closely related, hence the efficacy of zinc against both species. Reinforcing their commonality is that their access into a host cell uses the same cell surface receptor – ACE2.

Conclusions

Zinc is a vital immune-related micronutrient and possesses dual antiviral activity. It enhances the activity of both the innate and acquired immune system and impedes RNA-dependent RNA polymerase (RdRp). HCQ also has a putative duality of antiviral action. It interferes with the ACE2 receptor, potentially impeding ACE2/SARS-CoV-2 binding, and it has been shown to increase the endosomal pH, which may impair SARS-CoV-2 early-stage viral replication.

Triple therapy for five days of HCQ 400mg immediately then 200mg twice daily, AZM 500mg daily and zinc sulfate 220mg – containing 50mg elemental zinc – twice daily has shown clinical benefit in non-ICU bound patients.  These results are yet to be confirmed by peer review.

Finally, the use of HCQ in patients with a high CRP is without clinical justification.