Overview
Itraconazole is a broad-spectrum triazole antifungal agent used to treat various fungal infections. It works by inhibiting fungal cytochrome P450 enzymes, disrupting ergosterol synthesis in fungal cell membranes. It is particularly effective against dermatophytes, yeasts, and molds.
Mechanism of Action
Itraconazole inhibits fungal cytochrome P450-dependent 14α-demethylase, which converts lanosterol to ergosterol. This disruption of ergosterol synthesis compromises fungal cell membrane integrity and function, leading to fungal cell death.
Indications
- Onychomycosis (fungal nail infections)
- Systemic fungal infections (aspergillosis, blastomycosis, histoplasmosis)
- Oropharyngeal and esophageal candidiasis
- Dermatophytoses (tinea infections)
- Vulvovaginal candidiasis
Dosage
Dosage varies by indication: Onychomycosis: 200 mg once daily for 12 weeks; Systemic infections: 200-400 mg daily; Candidiasis: 100-200 mg daily. Take with food for optimal absorption. Capsules should be swallowed whole.
Contraindications
- Hypersensitivity to itraconazole or other azole antifungals
- Concomitant use with certain drugs metabolized by CYP3A4 (e.g., cisapride, pimozide, quinidine, dofetilide)
- Ventricular dysfunction or heart failure
- Pregnancy (except for life-threatening infections)
Side Effects
- Nausea, vomiting, diarrhea
- Headache, dizziness
- Elevated liver enzymes
- Hypokalemia
- Rash, pruritus
- Peripheral edema
- Fatigue
Interactions
- CYP3A4 substrates: increased levels of drugs like midazolam, triazolam, statins
- Enzyme inducers (rifampin, phenytoin): decreased itraconazole levels
- Acid-suppressing agents (PPIs, H2 blockers): reduced absorption
- Warfarin: increased anticoagulant effect
- Cyclosporine, tacrolimus: increased nephrotoxicity risk