Practical information on using polyenes

The polyenes nystatin and amphotericin B are used topically and systemically. Their spectrums of activity vary.

Nystatin is mainly active against Candida species¹. It is poorly absorbed orally and is not absorbed through skin or mucous membranes when applied topically.

Amphotericin B is active against a wide range of yeasts (including Candida and Cryptococcus species) and other fungi (including most Aspergillus species, but not A. terreus or A. nidulans), some Fusarium species, zygomycetes and phaeohyphomycetes, and Leishmania species.

Amphotericin B is associated with significant toxicity, including infusion-related adverse effects, nephrotoxicity, electrolyte abnormalities (especially hypokalaemia and hypomagnesaemia) and anaemia; monitoring is essential.

Adverse reactions are more common with amphotericin B desoxycholate (the ‘conventional’ form of amphotericin B). To minimise amphotericin B desoxycholate toxicity, prehydrate the patient with sodium chloride 0.9% (0.5 to 1 L intravenously, before amphotericin B infusion) and consider pretreatment with hydrocortisone, an antihistamine, an antiemetic, an analgesic or an antipyretic. If nephrotoxicity or severe infusion reactions occur with amphotericin B desoxycholate, consider switching to the liposomal formulation of amphotericin B, which is usually better tolerated.

The dosage and infusion rates for each amphotericin B formulation (conventional or liposomal) are significantly different – exercise caution if prescribing and administering amphotericin B because errors have caused fatalities.