Itraconazole

What is Itraconazole?

Itraconazole is a prescription antifungal medication belonging to the azole class of drugs. It is used to treat various fungal infections throughout the body, including nail infections, skin infections, and serious systemic fungal diseases. This broad-spectrum antifungal is available in capsule, oral solution, and intravenous formulations.

Uses

Itraconazole is approved for treating several types of fungal infections:

• Onychomycosis: Fungal infections of the fingernails and toenails, particularly effective against dermatophyte infections
• Aspergillosis: Serious lung infections caused by Aspergillus species, especially in immunocompromised patients
• Blastomycosis: A systemic fungal infection that can affect the lungs, skin, and other organs
• Histoplasmosis: A respiratory infection that can become disseminated in immunocompromised individuals
• Dermatophyte infections: Skin infections including athlete’s foot, ringworm, and jock itch when topical treatments are inadequate

How it works

Itraconazole works by inhibiting an enzyme called 14-alpha-demethylase, which is essential for fungal cells to produce ergosterol, a vital component of their cell membranes. Without adequate ergosterol production, the fungal cell membrane becomes unstable and leaky, ultimately leading to cell death. This mechanism specifically targets fungal cells while having minimal effect on human cell membranes.

Side effects

Common side effects include:

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• Nausea and vomiting
• Stomach pain or upset
• Diarrhea
• Headache
• Dizziness
• Fatigue
• Skin rash
• Changes in taste

Serious side effects requiring immediate medical attention:

• Heart failure symptoms (shortness of breath, swelling, rapid weight gain)
• Liver problems (yellowing of skin or eyes, dark urine, severe fatigue)
• Hearing loss or ringing in ears
• Severe allergic reactions
• Peripheral neuropathy (numbness or tingling in hands or feet)

Warnings and precautions

• Heart conditions: Itraconazole can worsen heart failure and should be avoided in patients with ventricular dysfunction or a history of heart failure
• Liver function: Regular liver function monitoring is required, as the drug can cause serious liver toxicity; avoid use in patients with active liver disease
• Pregnancy: Classified as FDA pregnancy category C; should not be used for nail infections in pregnant women and requires careful risk-benefit assessment for systemic infections
• Kidney impairment: Dose adjustments may be necessary in patients with severe kidney disease, particularly for intravenous formulations
• Gastric acidity: Requires acidic stomach environment for absorption; effectiveness may be reduced in patients taking acid-suppressing medications

Interactions

Itraconazole has numerous significant drug interactions due to its effects on liver enzymes:

• Warfarin: Increases bleeding risk by enhancing warfarin’s anticoagulant effects
• Digoxin: Raises digoxin levels, potentially causing dangerous heart rhythm problems
• Statins (simvastatin, lovastatin): Increases statin levels, raising risk of muscle damage and rhabdomyolysis
• Benzodiazepines (midazolam, triazolam): Prolongs sedative effects and may cause excessive drowsiness
• Calcium channel blockers: May increase blood pressure medication effects and cause hypotension
• Antacids and acid suppressors: Reduce itraconazole absorption when taken together
• Rifampin: Significantly decreases itraconazole effectiveness
• Cyclosporine: Increases immunosuppressant levels, requiring dose adjustments

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Dosage

Dosage varies significantly depending on the type and severity of infection being treated. For onychomycosis, typical dosing is 200 mg once daily for 12 weeks for toenails or 200 mg twice daily for one week per month for 2-3 months. For systemic infections like aspergillosis or histoplasmosis, doses typically range from 200-400 mg daily, with some severe cases requiring higher doses. The oral solution may have different dosing requirements than capsules due to improved absorption. All dosing should be individualized and determined by a healthcare provider based on the specific infection, patient factors, and response to treatment.

Sources: FDA DailyMed drug labels (public domain), BNF, WHO Essential Medicines List. This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting or stopping any medication.

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