Amphotericin B is poorly absorbed from the gastrointestinal tract. Oral amphotericin B is thus effective only on fungi within the lumen of the tract. The drug is widely distributed in tissues, but only 2-3% of the blood level is reached in CSF, thus occasionally necessitating intrathecal therapy for certain types of fungal meningitis.
Mechanism of Action: Amphotericin B binds to ergosterol (a cell membrane sterol) and alters the permeability of the cell by forming amphotericin B-associated pores in the cell membrane. The pore allows the leakage of intracellular ions and macromolecules, eventually leading to cell death.
Adverse Effects: The toxicity of amphotericin B which may occur immediately or delayed include fever, chills, muscle spasms, vomiting, headache, hypotension (related to infusion), renal damage associated with decreased renal perfusion (a reversible) and renal tubular injury (irreversible). Anaphylaxis, liver damage, anemia occurs infrequently.
Antifungal Activity: Amphotericin B is a broad-spectrum antifungal agent. It has activity against yeasts including; Candida albicans and Cryptococcus neoformans; molds, Aspergillus fumigatus.
Clinical Use: Amphotericin B remains the drug of choice for nearly all life-threatening mycotic infections. Used as the initial induction regimen for serious fungal infections (immunosuppressed patients, severe fungal pneumonia, and cryptococcal meningitis with altered mental status).
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