Amphotericin B
Amphotericin B treats serious systemic mycoses. Conventional deoxycholate, lipid-complex and liposomal formulations have different dosing and toxicity and are not interchangeable.
Group
Polyene antifungal
Mechanism of Action
Binding to fungal membrane ergosterol disrupts permeability and causes leakage of intracellular contents.
Dose Rates
Dog
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Systemic mycosis — deoxycholate | 0.5 mg/kg | IV | Every 48 h | Conventional deoxycholate only; slow infusion in 5% dextrose. Track cumulative exposure, generally 4–8 mg/kg, and stop earlier if renal toxicity develops. |
| Systemic mycosis — lipid complex | 1–3 mg/kg | IV | Every 48 h | Abelcet-type lipid complex only; slow infusion. Typical cumulative target 12–24 mg/kg, limited by renal tolerance. |
| Systemic mycosis — liposomal | 3–4 mg/kg | IV | Every 48 h | AmBisome-type liposomal formulation only; slow infusion. Typical cumulative target 12–30 mg/kg, limited by response and renal tolerance. |
Cat
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Systemic mycosis — deoxycholate | 0.25 mg/kg | IV | Conventional formulation; cautious starting amount. Subsequent interval and escalation require an individualized renal-monitoring plan. | |
| Systemic mycosis — lipid complex | 1–3 mg/kg | IV | Every 48 h | Abelcet-type lipid complex only; slow infusion. Typical cumulative target 12–24 mg/kg, limited by renal tolerance. |
| Systemic mycosis — liposomal | 3–4 mg/kg | IV | Every 48 h | AmBisome-type liposomal formulation only; slow infusion. Typical cumulative target 12–30 mg/kg, limited by response and renal tolerance. |
Horse
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Systemic mycosis — deoxycholate | 0.3 mg/kg | IV | Every 24 h | Up to 3 days; Conventional formulation by slow infusion; reassess after the three-day course. |
Indications
- Systemic mycoses including blastomycosis, histoplasmosis and coccidioidomycosis.
- Conventional canine courses commonly target a cumulative 4–8 mg/kg; renal tolerance may require earlier cessation.
- Lipid-complex courses commonly target 12–24 mg/kg cumulatively; liposomal courses commonly target 12–30 mg/kg. Adjust to organism, response and renal tolerance.
Contraindications
- Uncorrected dehydration or electrolyte derangement.
- Renal disease requires a deliberate formulation-specific risk assessment; conventional deoxycholate is particularly nephrotoxic.
- Prior amphotericin hypersensitivity requires a formulation-specific assessment, particularly if alternatives are available.
Interactions
- Aminoglycosides and other nephrotoxic drugs increase renal injury.
- Use the required dextrose diluent; saline or other electrolyte solutions may precipitate the drug. Give any saline loading separately.
Adverse effects
- Dose-limiting nephrotoxicity.
- Hypokalemia and hypomagnesemia from renal losses.
- Fever, tremors, phlebitis and infusion reactions.
Toxicity
Monitor creatinine, BUN, electrolytes, hydration and cumulative exposure throughout the course. Worsening azotemia or electrolyte losses require reassessment before further treatment. During dose escalation, renal indices may need checking every other day; once stable, reassess at least weekly, with electrolytes, CBC, urinalysis and hepatic indices as appropriate. Track body weight and hydration alongside cumulative drug exposure.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Amphotericin B deoxycholate 50 mg vial, reconstituted Add 10 mL sterile water to obtain 5 mg/mL concentrate; dilute further in 5% dextrose to 0.1 mg/mL or less for infusion. Conventional formulation only. | Injection | 50 mg / 10 mL | IV |
| AmBisome 50 mg vial, reconstituted Liposomal formulation. Add 12 mL sterile water to the vial to yield 4 mg/mL; filter and dilute further in dextrose. Not interchangeable with deoxycholate or lipid complex. | Injection | 4 mg / mL | IV |
