Amphotericin (Fungilin / Fungizone / Abelcet / AmBisome / Amphocil) or amphotericin B is an anti-fungal drug. It is an artificial version of a naturally occurring compound produced by the fungus Streptomyces nodosus.

Amphotericin works by binding irreversibly to ergosterol, a major component of the fungal cell membrane. It has powerful anti-fungal activity.

The tablet form of amphotericin is marketed under the brand name Fungilin and is approved for the treatment of thrush in the intestines. The intravenous form, called Fungizone, is approved for the treatment of severe or systemic fungal infections such as cryptococcal meningitis, aspergillosis, blastomycosis, coccidioidomycosis and histoplasmosis. It is also used to treat and prevent visceral leishmaniasis in patients with HIV^[1]. Amphotericin lozenges or suspension can be an effective treatment for thrush in the mouth, particularly where fluconazole (Diflucan) has not worked^[2].

Three lipid-based forms of amphotericin are approved in the United Kingdom for the treatment of severe or systemic fungal infections. These are liquids, which are administered by intravenous infusion. They cause fewer side effects than conventional amphotericin.

One version is marketed under the trade name AmBisome. This is a liposome-encapsulated form of amphotericin. A different molecule called amphotericin B lipid complex (ABLC) consists of two fatty substances and amphotericin. This is approved as a treatment for severe fungal infections in people who have not responded to conventional amphotericin, or to other systemic anti-fungal drugs, or who cannot take conventional amphotericin because of kidney impairment or other problems. Its side-effects include temporary increases in liver enzymes, temporary kidney toxicity, fever and chills. This version is marketed as Amphocil and as Abelcet.

A randomised controlled trial comparing AmBisome with standard amphotericin found the lipid-based form produced significantly greater clinical improvement and was less toxic^[3].

Serious side-effects of amphotericin are common, including the abnormal presence of urea and other nitrogen substances in the blood, fever, chills, muscle pain, nausea, vomiting, loss of appetite, anaemia, kidney problems, inflammation of the veins, blood clot formation, headache and potassium deficiency. Side-effects may be minimised by taking paracetamol and an anti-histamine. However, taking an anti-histamine may be dangerous in patients also taking protease inhibitors.

Due to the risk of kidney damage, tenofovir (Viread) and amphotericin should be co-administered with caution. Amphotericin does not interact with any currently available protease inhibitors or non-nucleoside reverse transcriptase inhibitors (NNRTIs).