Amphotericin B

Amphotericin B: Uses, Dosage, and Side Effects

Overview

• It binds to sterols in fungal cell membrane creating pores and allowing leakage of contents.
• 50 mg/vial powder for reconstitution.

Uses of Amphotericin B

• Management of systemic fungal infections and leishmaniasis.

Dose of Amphotericin B  in Dogs and Cats

Dogs:

• Systemic mycoses: Conventional amphotericin: 0.25–1 mg/kg i.v. q48h. Administer slowly over 4–6 hours. ( Reconstitute vial with 10 ml water giving 5 mg/ml solution; dilute required volume further 1:50 with 5% dextrose water to give 0.1 mg/ml solution. Alternatively, 0.25–1 mg/kg may be dissolved in 10–60 ml 5% dextrose given over 10 min i.v. 3 times a week.) Start at the lower end of the dose range and increase gradually as the patient tolerates therapy. Several months of therapy are often necessary.

• Cryptococcosis (conventional amphotericin, subcutaneous alternative): 0.5–0.8 mg/kg added to 400–500 ml of 0.45% saline/2.5% dextrose. This total volume is then administered s.c. 2–3 times a week to a cumulative level of 8–26 mg/kg. Do not inject more concentrated solutions than 20 mg/l as they cause subcutaneous abscesses. Intralesional injections may also be performed in this condition at a dose of 1 mg/kg q7d in combination with oral itraconazole.
• Irrigation of bladder: Conventional amphotericin: 30–50 mg in 50–100 ml of sterile water infused at a rate of 5–10 ml/kg into the bladder lumen daily for 5–15 days.
• Systemic mycoses: Lipid formulations (general guidelines): 1 mg/kg q48h to a cumulative dose of 12 mg/kg. Higher doses are tolerated (e.g. 1–2.5 mg/kg i.v. q48h for 4 weeks/to a cumulative dose of 24–30 mg/kg). Reconstitute to 5 mg/ml with sterile water, then dilute the required volume to 1 mg/ml with 5% dextrose water.

• Leishmaniosis (lipid formulations): 1–2.5 mg/kg i.v. twice weekly for 8 injections. Increase the dose rate gradually. A total cumulative dose of at least 10 mg/kg is required but treatment may be continued long-term depending on clinical response. Use in this context is discouraged to avoid resistance developing to therapy for humans.

Cats:

• Systemic mycoses: Conventional amphotericin: 0.1–0.25 i.v. q48h. For details on administration, see doses for dogs.
• Cryptococcosis (conventional amphotericin, subcutaneous alternative): Conventional amphotericin: 0.5–0.8 mg/kg added to 400–500 ml of 0.45% saline/2.5% dextrose. This total volume is then administered s.c. 2–3 times a week to a cumulative level of 10–15 mg/kg. Do not inject more concentrated solutions than 20 mg/l as they cause subcutaneous abscesses. Intralesional injections may also be performed in this condition at a dose of 1 mg/kg q7d in combination with oral itraconazole.
• Systemic mycoses: Lipid formulations (general guidelines): 1 mg/kg q48h to a cumulative dose of 12 mg/kg. Higher doses are tolerated (e.g. 1–2.5 mg/kg i.v. q48h for 4 weeks/to a cumulative dose of 24–30 mg/kg).

Side Effects of Amphotericin B in Dogs and Cats

• Hypokalemia, which can cause anaphylactic reactions.
• Phlebitis.
• Hepatic failure.
• Renal failure
• vomiting
• Diarrhoea
• Pyrexia.

Contraindications of Amphotericin B in Dogs and Cats

• Do not use in renal or hepatic failure.

Some Notes:

• Use caution when taking other nephrotoxic medications because nephrotoxicity is a serious problem.
• Saline or lactated Ringer’s infusion (5 ml/kg/hr) for 30 minutes before and 120 minutes after the dose of amphotericin B may minimize nephrotoxicity (be sure to fully wash your IV line with 5% dextrose water in between).
• Pre-treating with aspirin, diphenhydramine, or an antiemetic can reduce fever and vomiting.