Oral Amphotericin B for Immunocompromised Patients
Oral amphotericin B is not recommended for treating systemic fungal infections in immunocompromised patients because it is not absorbed from the gastrointestinal tract and has no role in managing blood-borne or invasive fungal infections. 1
Why Oral Amphotericin B Doesn't Work for Systemic Infections
Amphotericin B administered orally (as capsules or suspension) remains in the gastrointestinal tract and is not systemically absorbed, making it ineffective for invasive fungal infections 2, 3
The physical-chemical properties of amphotericin B prevent adequate absorption from the GI tract at concentrations sufficient to treat blood-borne fungal infections 3
Oral amphotericin B capsules (500 mg four times daily) have historically been used only for prophylaxis of superficial fungal colonization in the GI tract, not for treatment of invasive disease 2
Appropriate Amphotericin B Formulations for Immunocompromised Patients
For immunocompromised patients requiring amphotericin B therapy, intravenous formulations must be used:
First-Line IV Options:
Liposomal amphotericin B (L-AmB) at 3-5 mg/kg IV daily is the preferred formulation due to reduced nephrotoxicity compared to conventional amphotericin B 1
For mucormycosis specifically, liposomal amphotericin B should be dosed at minimum 5 mg/kg/day, with consideration of up to 10 mg/kg/day in severe cases 1
Amphotericin B deoxycholate (AmB-d) at 0.5-1.5 mg/kg IV daily remains an alternative when lipid formulations are unavailable or cost-prohibitive, though nephrotoxicity occurs in up to 24% of patients 1
Clinical Context for Use:
Amphotericin B formulations are indicated for invasive aspergillosis, mucormycosis, disseminated candidiasis, cryptococcosis, and histoplasmosis in immunocompromised hosts 1
For candidemia in immunocompromised patients, echinocandins are now preferred over amphotericin B as first-line therapy, with amphotericin B reserved for cases of intolerance or limited availability 1
Alternative Oral Antifungal Options
If oral therapy is specifically needed for an immunocompromised patient:
Fluconazole 400-800 mg daily orally is appropriate for susceptible Candida species (excluding C. krusei and often C. glabrata) after clinical stabilization 1, 4
Itraconazole oral solution 200 mg twice daily can be used for histoplasmosis and as prophylaxis in high-risk patients 1, 2
Posaconazole oral suspension 200 mg four times daily or tablets 300 mg daily are options for aspergillosis and mucormycosis as salvage therapy 1
Voriconazole 200 mg orally twice daily (after loading) can be used for step-down therapy in selected cases 1
Critical Pitfalls to Avoid
Never prescribe oral amphotericin B capsules expecting systemic antifungal activity—this is a fundamental error that will result in treatment failure 2, 3
Do not confuse oral amphotericin B (non-absorbed) with intravenous liposomal amphotericin B—these are completely different formulations with different indications 5, 6
Experimental oral formulations incorporating amphotericin B into lipid carriers for systemic absorption remain investigational and are not clinically available 3