Usage
Micafungin is an antifungal medication primarily used to treat and prevent invasive Candida infections. This includes candidemia, acute disseminated candidiasis, Candida peritonitis, abscesses, and esophageal candidiasis. It’s also used prophylactically in patients undergoing hematopoietic stem cell transplantation (HSCT) who are at high risk of developing Candida infections.
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Pharmacological Classification: Echinocandin antifungal.
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Mechanism of Action: Micafungin noncompetitively inhibits the synthesis of 1,3-β-D-glucan, an essential component of the fungal cell wall. This leads to cell wall instability and fungal cell death.
Alternate Names
How It Works
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Pharmacodynamics: Micafungin exerts its antifungal activity by disrupting the fungal cell wall. By inhibiting 1,3-β-D-glucan synthase, it prevents the formation of 1,3-β-D-glucan, a crucial polysaccharide in the fungal cell wall. This weakens the structural integrity of the cell wall, leading to cell lysis and death. Micafungin exhibits fungicidal activity against some Candida species at higher concentrations and fungistatic activity at lower concentrations, particularly against Aspergillus.
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Pharmacokinetics:
- Absorption: Administered intravenously, therefore 100% bioavailability.
- Distribution: Highly protein-bound (>99%). Micafungin demonstrates dose-dependent penetration into the central nervous system (CNS).
- Metabolism: Limited hepatic metabolism.
- Elimination: Primarily through biliary excretion; a small portion is renally excreted. The elimination half-life allows for once-daily dosing.
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Mode of Action: Micafungin targets the fungal cell wall by inhibiting 1,3-β-D-glucan synthase. This enzyme is critical for the synthesis of 1,3-β-D-glucan, a major structural component of the fungal cell wall.
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Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: Micafungin acts through noncompetitive inhibition of 1,3-β-D-glucan synthase.
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Elimination Pathways: Primarily biliary excretion with minimal renal excretion. It is not dialyzable due to high protein binding.
Dosage
Standard Dosage
Adults:
- Candidemia, Acute Disseminated Candidiasis, Candida Peritonitis and Abscesses: 100 mg IV once daily. If the response is inadequate, the dose can be increased to 200 mg daily.
- Esophageal Candidiasis: 150 mg IV once daily.
- Prophylaxis of Candida Infections in HSCT Recipients: 50 mg IV once daily.
Children (4 months and older):
- Candidemia, Acute Disseminated Candidiasis, Candida Peritonitis and Abscesses: 2 mg/kg IV once daily (maximum 100 mg/day).
- Esophageal Candidiasis: 3 mg/kg IV once daily for patients ≤30 kg; 2.5 mg/kg IV once daily for patients >30 kg (maximum 150 mg/day).
- Prophylaxis of Candida Infections in HSCT Recipients: 1 mg/kg IV once daily (maximum 50 mg/day).
Children (younger than 4 months):
- Candidemia, Acute Disseminated Candidiasis, Candida Peritonitis and Abscesses (without meningoencephalitis and/or ocular dissemination): 4 mg/kg IV once daily.
- Candidemia with suspected CNS involvement: 10 mg/kg/day.
Special Cases:
- Elderly Patients: No dose adjustment is necessary.
- Patients with Renal Impairment: No dose adjustment is necessary.
- Patients with Hepatic Dysfunction: No dose adjustment is necessary.
- Patients with Comorbid Conditions: Consider individual patient factors and adjust dose as needed.
Clinical Use Cases
The dosage recommendations for the specific clinical use cases mentioned (intubation, surgical procedures, mechanical ventilation, ICU use, emergency situations) are the same as the standard dosages based on the indication for Micafungin use.
Dosage Adjustments
No specific dosage adjustments are required based on race or gender.
Side Effects
Common Side Effects:
- Nausea, vomiting, diarrhea
- Flushing
- Mild itching or rash
- Hypokalemia
- Fever
- Headache
- Thrombocytopenia
- Abdominal Pain
- Mucosal inflammation
- Hypertension
Rare but Serious Side Effects:
- Hypersensitivity reactions (anaphylaxis, anaphylactoid reactions)
- Hemolytic anemia, acute intravascular hemolysis, hemoglobinuria
- Hepatotoxicity (liver injury)
- Renal toxicity
Long-Term Effects:
- Potential for liver tumors with prolonged use (observed in animal studies).
Adverse Drug Reactions (ADR):
- Anaphylaxis (severe allergic reaction) requires immediate medical attention.
- Hemolysis or hemolytic anemia necessitate close monitoring and evaluation of treatment continuation.
Contraindications
- Hypersensitivity to micafungin, other echinocandins, or any component of the formulation.
Drug Interactions
Micafungin has clinically significant drug interactions with several medications, including:
- Sirolimus: Increased sirolimus levels.
- Itraconazole: Potential for altered levels of either drug.
- Nifedipine: Potential for altered levels of either drug.
Refer to a comprehensive drug interaction database for the most up-to-date and detailed information on micafungin drug interactions.
Pregnancy and Breastfeeding
- Pregnancy: Micafungin may cause fetal harm based on animal data. Use only if clearly needed and the benefit outweighs the risk to the fetus.
- Breastfeeding: While limited human data is available, micafungin is likely excreted in breast milk. Caution is advised, and a risk/benefit assessment should be performed when administering to breastfeeding women.
Drug Profile Summary
- Mechanism of Action: Inhibits fungal cell wall synthesis by targeting 1,3-β-D-glucan synthase.
- Side Effects: Common: Nausea, vomiting, diarrhea, flushing, itching, rash. Serious: Hypersensitivity reactions, hemolytic anemia, hepatotoxicity, nephrotoxicity.
- Contraindications: Hypersensitivity to micafungin or other echinocandins.
- Drug Interactions: Sirolimus, itraconazole, nifedipine. Consult a drug interaction database for a complete list.
- Pregnancy & Breastfeeding: Potential fetal risk; caution advised during breastfeeding.
- Dosage: See detailed dosage section above.
- Monitoring Parameters: Liver function tests, renal function tests, complete blood count (CBC), signs and symptoms of hypersensitivity.
Popular Combinations
Micafungin is sometimes used in combination with other antifungal agents, especially in cases of refractory or severe infections, though information on “popular combinations” is limited.
Precautions
- General Precautions: Monitor for hypersensitivity reactions, liver function, and renal function.
- Specific Populations: Assess risk/benefit in pregnant/breastfeeding women. No dose adjustment is needed for elderly or renally/hepatically impaired patients.
- Lifestyle Considerations: No specific lifestyle considerations have been identified.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Micafungin?
A: See the detailed dosage section above, which includes standard dosing for adults, pediatrics, and special populations.
Q2: What are the common side effects of Micafungin?
A: Common side effects include nausea, vomiting, diarrhea, flushing, rash, itching, hypokalemia, fever, headache, thrombocytopenia, abdominal pain, mucosal inflammation, and hypertension.
Q3: How is Micafungin administered?
A: Micafungin is administered intravenously as a slow infusion over approximately 1 hour.
Q4: Is Micafungin safe to use during pregnancy?
A: Micafungin should be used during pregnancy only if clearly needed and the benefit outweighs the potential risk to the fetus. Animal studies suggest potential fetal harm.
Q5: What should I do if a patient experiences a hypersensitivity reaction to Micafungin?
A: Discontinue Micafungin immediately and administer appropriate medical treatment for hypersensitivity, such as epinephrine and corticosteroids.
Q6: Does Micafungin require dose adjustment in patients with renal impairment?
A: No, dose adjustment is not necessary in patients with renal impairment.
Q7: What is the mechanism of action of Micafungin?
A: Micafungin inhibits the synthesis of 1,3-β-D-glucan, a key component of the fungal cell wall, leading to cell wall instability and fungal cell death.
Q8: Can Micafungin be used to treat infections caused by fungi other than Candida?
A: The efficacy of micafungin against infections caused by fungi other than Candida has not been established. While it shows some in vitro activity against Aspergillus, clinical data supporting its routine use for aspergillosis is lacking. It may be considered in cases of refractory aspergillosis or in combination with other antifungals, based on expert guidance.
Q9: What is the duration of treatment with Micafungin?
A: Treatment duration depends on the infection being treated and clinical response. For invasive candidiasis, treatment should continue for at least 14 days. For prophylaxis in HSCT patients, treatment is continued for at least one week after neutrophil recovery.
