What it's for (Indications)
- Amphotericin B is a potent broad-spectrum antifungal agent primarily indicated for the treatment of severe, progressive, and potentially life-threatening fungal infections.
- It is a critical therapeutic option for systemic mycoses, including but not limited to aspergillosis, disseminated candidiasis, cryptococcosis (especially cryptococcal meningitis), blastomycosis, coccidioidomycosis, histoplasmosis, and mucormycosis (zygomycosis).
- It is also utilized in the management of severe visceral leishmaniasis.
- Additionally, amphotericin B is employed as empirical therapy in febrile neutropenic patients with suspected fungal infections who have not responded to broad-spectrum antibacterial agents.
- The decision to use amphotericin B should be based on the severity of the infection, the causative organism's susceptibility, and the patient's immune status, often reserved for cases unresponsive to or intolerant of less toxic antifungal agents.
- Its use extends to deep-seated fungal infections where other therapies have failed or are contraindicated, particularly in immunocompromised individuals.
- Given its toxicity profile, its use is generally restricted to serious or life-threatening conditions.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | The dosage of amphotericin B is highly individualized based on the specific fungal infection, the patient's clinical status, tolerance, and the formulation used (conventional deoxycholate vs. lipid formulations). For conventional Amphotericin B (AmB deoxycholate), a test dose of 1 mg in 20 mL of 5% Dextrose Injection (D5W) infused intravenously over 20-30 minutes is typically administered to assess acute adverse reactions. The initial therapeutic dose usually begins at 0.25 mg/kg body weight, infused slowly over 2-6 hours. This dose may be gradually increased by 0.25 mg/kg increments daily or every other day, up to a maximum daily dose of 0.5 to 1.0 mg/kg, generally not exceeding 1.5 mg/kg/day due to heightened risk of nephrotoxicity. The total cumulative dose varies widely, often ranging from 1.5 to 4 grams for severe systemic infections. Lipid formulations (e.g., liposomal amphotericin B, amphotericin B lipid complex) permit higher daily doses (e.g., 3-5 mg/kg/day) with a reduced incidence of nephrotoxicity and infusion-related reactions, but specific product monographs must be consulted for precise dosing. All formulations must be administered via slow intravenous infusion, and vigilant monitoring of renal function, serum electrolytes (particularly potassium and magnesium), and liver function is paramount throughout therapy. Pre-medication with antipyretics, antihistamines, and corticosteroids is often necessary to ameliorate infusion-related symptoms. |
Safety & Warnings
Common Side Effects
- Amphotericin B, particularly the conventional deoxycholate formulation, is associated with a high incidence of adverse effects, which can be severe.
- Common 'infusion-related reactions' occur within 1-3 hours of administration and include fever, chills, rigors, headache, nausea, vomiting, malaise, myalgia, arthralgia, hypotension, and tachypnea.
- These can often be mitigated by pre-medication.
- 'Nephrotoxicity' is a major dose-limiting toxicity, manifesting as renal impairment, azotemia, hypokalemia, hypomagnesemia, and renal tubular acidosis, potentially leading to irreversible kidney damage.
- Regular monitoring of serum creatinine, blood urea nitrogen (BUN), and electrolytes is crucial.
- 'Hematologic effects' include normochromic, normocytic anemia, leukopenia, and thrombocytopenia.
- 'Gastrointestinal disturbances' such as anorexia, dyspepsia, diarrhea, and abdominal pain are also reported.
- 'Hepatic effects' may include elevated liver enzymes (AST, ALT, bilirubin).
- 'Cardiovascular effects' can involve arrhythmias, hypertension, hypotension, and rarely, cardiac arrest.
- 'Neurological adverse effects' are rare but serious, encompassing seizures, peripheral neuropathy, and encephalopathy.
- 'Local reactions' at the injection site, such as phlebitis and thrombophlebitis, can occur.
- 'Hypersensitivity reactions' ranging from rash and pruritus to severe anaphylaxis are also possible.
- While lipid formulations generally offer an improved safety profile regarding nephrotoxicity and infusion reactions, these adverse effects can still manifest.
Serious Warnings
- Black Box Warning: AMPHOTERICIN B DEOXYCHOLATE INJECTION SHOULD BE USED PRIMARILY FOR TREATMENT OF PATIENTS WITH PROGRESSIVE, POTENTIALLY LIFE-THREATENING FUNGAL INFECTIONS. THIS DRUG SHOULD NOT BE USED TO TREAT NON-INVASIVE FORMS OF FUNGAL DISEASE SUCH AS ORAL THRUSH, VAGINAL CANDIDIASIS, OR ESOPHAGEAL CANDIDIASIS IN PATIENTS WITH NORMAL NEUTROPHIL COUNTS. Amphotericin B deoxycholate is associated with significant toxicity, particularly dose-related nephrotoxicity and acute infusion-related reactions, which can be severe and life-threatening. Patients receiving amphotericin B deoxycholate must be under close medical supervision, and hospitalization is generally recommended for the initiation of therapy. Renal function (serum creatinine, blood urea nitrogen), serum electrolytes (especially potassium and magnesium), and liver function tests should be monitored frequently (e.g., daily initially, then 2-3 times weekly) throughout the course of treatment. Complete blood counts should also be regularly assessed due to the risk of hematologic abnormalities. A test dose (e.g., 1 mg administered intravenously over 20-30 minutes) should be given to assess patient tolerance. While a test dose may not predict severe anaphylactic reactions, it can help identify patients at higher risk for acute infusion-related adverse events. Infusion reactions such as fever, chills, rigors, hypotension, nausea, and vomiting are common; these reactions can often be ameliorated by slowing the infusion rate and by pre-medication with antipyretics, antihistamines, or corticosteroids. Lipid formulations of amphotericin B may have a different toxicity profile compared to conventional amphotericin B deoxycholate, often with reduced nephrotoxicity and infusion reactions, but they still require careful monitoring and management.
- Amphotericin B necessitates vigilant medical supervision and monitoring due to its significant toxicity.
- 'Nephrotoxicity' is a primary concern; renal function (serum creatinine, BUN, creatinine clearance) must be monitored frequently (initially daily, then 2-3 times weekly).
- Dosage adjustments or a switch to lipid formulations may be required to manage renal dysfunction.
- Adequate hydration is crucial, and concomitant administration of other nephrotoxic drugs should be avoided if possible.
- 'Infusion-related reactions' are common and can be severe; pre-medication with antipyretics, antihistamines, and corticosteroids is strongly recommended to reduce their incidence and severity.
- Slow infusion rates (over 2-6 hours) are essential.
- 'Electrolyte imbalances,' particularly hypokalemia and hypomagnesemia, are frequent and can be profound, necessitating close monitoring and aggressive supplementation to prevent cardiac arrhythmias and other complications.
- 'Hematologic effects,' including anemia, warrant regular complete blood count (CBC) monitoring.
- 'Hepatic function' should also be assessed via liver function tests.
- In 'pregnancy and lactation,' amphotericin B should only be used if the potential benefit clearly justifies the potential risks.
- 'Drug interactions' are significant; amphotericin B can potentiate the toxicity of other nephrotoxic agents and corticosteroids.
- 'Anaphylaxis' is a rare but life-threatening hypersensitivity reaction, requiring immediate access to emergency resuscitative equipment.
- Patients should ideally be hospitalized for the initiation of therapy due to the potential for acute, severe adverse events.
How it Works (Mechanism of Action)
Amphotericin B is a polyene macrolide antifungal antibiotic that exerts its primary mechanism of action by binding to ergosterol, a sterol uniquely present in the fungal cell membrane, distinguishing it from mammalian cell membranes that contain cholesterol. Upon binding to ergosterol, amphotericin B molecules integrate into the fungal cell membrane, forming transmembrane channels or pores. These pores disrupt the structural integrity and permeability of the fungal cell membrane, leading to an uncontrolled leakage of essential intracellular components. Key cellular contents such as potassium ions, amino acids, nucleotides, and other small molecules leak out, severely compromising the fungal cell's metabolic processes and ionic homeostasis. This progressive loss of vital intracellular constituents ultimately leads to profound cellular dysfunction, metabolic collapse, and osmotic lysis, resulting in fungal cell death, thereby demonstrating a fungicidal effect. The selective toxicity of amphotericin B is attributed to its significantly higher affinity for ergosterol in fungal cells compared to cholesterol in mammalian cells. However, some degree of binding to cholesterol can occur, which contributes to the drug's inherent toxicity in human patients, most notably nephrotoxicity. Resistance to amphotericin B is uncommon but can arise through mechanisms involving a reduction in ergosterol content within the fungal cell membrane or structural modifications to ergosterol, which diminish the drug's binding efficacy.
Commercial Brands (Alternatives)
No other brands found for this formula.