Drug Groups

approved; investigational

Description

Amphotericin B shows a high order of in vitro activity against many species of fungi. Histoplasma capsulatum, Coccidioides immitis, Candida species, Blastomyces dermatitidis, Rhodotorula, Cryptococcus neoformans, Sporothrix schenckii, Mucor mucedo, and Aspergillus fumigatus are all inhibited by concentrations of amphotericin B ranging from 0.03 to 1.0 mcg/mL in vitro. While Candida albicans is generally quite susceptible to amphotericin B, non-albicans species may be less susceptible. Pseudallescheria boydii and Fusarium sp. are often resistant to amphotericin B. The antibiotic is without effect on bacteria, rickettsiae, and viruses.

Indication

Used to treat potentially life threatening fungal infections.

Pharmacology

Amphotericin B shows a high order of in vitro activity against many species of fungi. Histoplasma capsulatum, Coccidioides immitis, Candida species, Blastomyces dermatitidis, Rhodotorula, Cryptococcus neoformans, Sporothrix schenckii, Mucor mucedo, and Aspergillus fumigatus are all inhibited by concentrations of amphotericin B ranging from 0.03 to 1.0 mcg/mL in vitro. While Candida albicans is generally quite susceptible to amphotericin B, non-albicans species may be less susceptible. Pseudallescheria boydii and Fusarium sp. are often resistant to amphotericin B. The antibiotic is without effect on bacteria, rickettsiae, and viruses.

Toxicity

Oral, rat: LD₅₀ = >5 gm/kg. Amphotericin B overdoses can result in cardio-respiratory arrest.

Affected Organisms

Biotransformation

Exclusively renal

Absorption

Bioavailability is 100% for intravenous infusion.

Half Life

An elimination half-life of approximately 15 days follows an initial plasma half-life of about 24 hours.

Protein Binding

Highly bound (>90%) to plasma proteins.

Clearance

* 39 +/- 22 mL/hr/kg [febrile neutropenic cancer and bone marrow transplant patients receiving infusion of 1 mg/kg/day at Day 1]
* 17 +/- 6 mL/hr/kg [febrile neutropenic cancer and bone marrow transplant patients receiving infusion of 1 mg/kg/day 3-20 days later]
* 51 +/- 44 mL/hr/kg [febrile neutropenic cancer and bone marrow transplant patients receiving infusion of 2.5 mg/kg/day at Day 1]
* 22 +/- 15 mL/hr/kg [febrile neutropenic cancer and bone marrow transplant patients receiving infusion of 2.5 mg/kg/day 3-20 days later]
* 21 +/- 14 mL/hr/kg [febrile neutropenic cancer and bone marrow transplant patients receiving infusion of 5 mg/kg/day at Day 1]
* 11 +/- 6 mL/hr/kg [febrile neutropenic cancer and bone marrow transplant patients receiving infusion of 5 mg/kg/day 3-20 days later]

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