Antifungals

Rapid Review

• Mechanism of Action: Anti-fungal; binds to ergosterol in fungal membranes and causes intracellular contents to leak out.
• Indications: used for severe or disseminated fungal infections (invasive aspergillosis, cryptococcal meningitis, blastomycosis, coccidiomycosis)
• Contraindications: allergy to class/drug
• Dosage: Dosage varies significantly based on formulation. Generally, a single test dosage (1 mg in 20 mL of 5% dextrose) is infused over 20-30 minutes with close monitoring. If tolerated, then give a single daily dosage of 0.25mg/kg.
• Half-life: Up to 14 days; depending on dosage
• Adverse Reactions: Associated with significant renal toxicity. May also cause fever, chills, muscle rigor, and hypotension
• Special Considerations: May cause hypokalemia and hypomagnesemia. Should be supplemented with potassium and magnesium. IV fluids help minimize nephrotoxicity.

Pearls

Deep Dive

• Amphotericin B (Drugs.com)

Rapid Review

• Mechanism of Action: Azole antifungal; inhibits 14-alpha demethylase and reduces fungal cell membrane synthesis.
• Indications: Tinea infections (ringworm, jock itch, athletes foot), pityriasis versicolor, oropharyngeal candidiasis, vulvovaginal candidiasis
• Contraindications: Allergy to drug/class
• Dosage:
  • Tinea infections: Topical 1% cream applied bid x 2-4 weeks
  • Oropharyngeal infection: 10mg PO 5 times daily x 14 days
  • Vulvovaginal infection: 1 applicator 2% PV qhs x 3 days
• Half-life: Unknown
• Adverse Reactions: Itching, nausea, vomiting.
• Special Considerations: Oral formulations may cause abnormal liver function tests in 10% of patients.

Pearls

Deep Dive

• Clotrimazole (PubMed)

Rapid Review

• Mechanism of Action: Triazole antifungal; inhibits cytochrome P450 to prevent egosterol synthesis to increase cellular permeability.
• Indications: Vaginal, oropharyngeal, or esophageal candidiasis. Systemic candida infections.
• Contraindications: Allergy to drug/class, coadministration with drugs that prolong QT intervals
• Dosage:
  • Vaginal candidiasis: Single 150mg dose PO
  • Esophageal/oropharyngeal candidiasis: 100mg PO q daily x 2 weeks
• Half-life: 24 hours
• Adverse Reactions: GI symptoms (nausea, abdominal pain, diarrhea), anaphylaxis, hepatotoxicity, QT prolongation
• Special Considerations: 
• Fluconazole is an antifungal medication used to treat candidal infections (e.g. vaginal yeast infection), tinea as well as invasive fungal infections.

Pearls

Deep Dive

• Fluconazole (PubMed)