Hospira have now launched DBL™ Sodium Nitroprusside Concentrate Injection, a 50mg/2mL solution, to replace the recently supplied Section 14 ‘stop gap’ used since unexpectedly discontinuing the old powder for injection.
Sodium nitroprusside quickly reduces blood pressure by relaxing vascular smooth muscles to exclusively dilate peripheral veins and, to a slightly lesser degree, arteries; decreasing both the preload and afterload of the heart.
It is used to reduce blood pressure in hypertensive crises, to reduce bleeding in some surgical procedures, and as initial management of cardiac failure prior to commencing oral therapy.
Its potency necessitates it only being administered, diluted in 500-1000mL of 5% dextrose, via a volumetric infusion pump and with constant monitoring of blood pressure.
Saturation of metabolic pathways can occur within an hour at full infusion rates, releasing free cyanide. Metabolic (lactic) acidosis may only appear after cyanide levels are dangerous, and progression to death can be rapid. Observe for bright red venous blood, air hunger, and confusion.
Judicious co-administration of sodium thiosulfate greatly increases the body’s capacity to eliminate cyanide, although the resultant thiocyanate can also be toxic, and should be monitored daily in extended infusions.
Contraindications include uncorrected anaemia, severe renal disease, diseases associated with vitamin B12 deficiency, those rare patients with high cyanide/thiocyanate ratios, compensatory hypertension, and acute congestive heart failure associated with reduced peripheral vascular resistance.