Edaravone on the PBS

Edaravone was recently added to the Pharmaceutical Benefits Scheme (PBS) for the treatment of amyotrophic lateral sclerosis (ALS).

Oxidative stress is thought to be a key factor in the progression of ALS, causing damage to motor neurons. While the exact mechanism of action of edaravone in ALS is not currently known, it acts as a free radical scavenger which may minimise this damage.

Edaravone is administered as an intravenous infusion over 60 minutes. There is an initial induction period of daily dosing for 14 days, followed by a 14-day drug-free period. Subsequent cycles involve daily dosing for 10 days out of 14-day periods, followed by a 14-day drug-free period.

Studies on the efficacy of edaravone have yielded conflicting results, with genetic differences potentially playing a role. Randomised controlled trials suggest that the following factors increase the likelihood of a favourable response to edaravone:

• Forced vital capacity (FVC) of at least 80% before treatment;
• Score at least 2 points or better on each item of the ALS Functional Rating Scale – Revised (ALSFRS-R), i.e. functionality retained in most activities of daily living; and
• Initiating edaravone within two years of symptom onset.

These factors are reflected in the clinical criteria of the PBS approval.