Mesmor (Itraconazole)

Itraconazole is an azole antifungal used to treat systemic and cutaneous fungal infections.

• Dermatophytosis: effective in clearing skin infections caused by dermatophytes.
• Onychomycosis: promotes regrowth of healthy nail tissue by eradicating the infecting fungus.
• Blastomycosis: resolves pulmonary and disseminated disease caused by Blastomyces dermatitidis.
• Histoplasmosis: treats acute and chronic infection from Histoplasma capsulatum.
• Coccidioidomycosis: manages valley fever caused by Coccidioides species.
• Aspergillosis: controls invasive disease due to Aspergillus spp.

• Itraconazole exerts its antifungal activity by inhibiting the fungal cytochrome P450 enzyme lanosterol 14α‑demethylase. This blockade prevents the conversion of lanosterol to ergosterol, a vital component of the fungal cell membrane, leading to accumulation of toxic sterol intermediates and increased membrane permeability, ultimately halting fungal growth and replication. The drug is highly lipophilic, allowing extensive tissue distribution, and is metabolized primarily by hepatic CYP3A4, which contributes to its prolonged half‑life and potential for drug‑drug interactions.

Itraconazole may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Vomiting: occasional emesis.
• Abdominal pain: cramping or discomfort.
• Headache: transient mild headache.
• Rash: mild skin irritation.
• Taste disturbance: altered taste sensation.

Serious or Rare Side Effects

• Hepatotoxicity: elevated liver enzymes or liver injury.
• Congestive heart failure: fluid retention and worsening cardiac function.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• QT prolongation: cardiac rhythm disturbances that may lead to arrhythmia.

Before initiating itraconazole therapy, several safety considerations should be reviewed.

• Liver function monitoring: obtain baseline hepatic enzymes and repeat periodically.
• Cardiac assessment: avoid in patients with existing heart failure or monitor for fluid retention.
• Drug interaction review: evaluate concomitant medications metabolized by CYP3A4.
• Pregnancy and lactation: use only if potential benefit justifies risk, as safety data are limited.
• Dose adjustment: consider reduced dosing in patients with moderate hepatic impairment.
• Store at room temperature: keep in original packaging, protect from moisture and light.

Itraconazole has a high potential for drug‑drug interactions due to CYP3A4 inhibition and other mechanisms.

Major Interactions (Avoid)

• Certain statins (e.g., simvastatin, lovastatin): risk of rhabdomyolysis.
• Antiarrhythmic agents (e.g., quinidine, amiodarone): may cause serious cardiac effects.
• HIV protease inhibitors (e.g., ritonavir): can lead to toxic itraconazole levels.
• Ergot derivatives (e.g., ergotamine): risk of ergotism.
• Rifampin and other strong CYP3A4 inducers: markedly reduce itraconazole exposure.

Moderate Interactions (Monitor Closely)

• Oral contraceptives: decreased efficacy, consider backup method.
• Warfarin: possible increase in INR, monitor coagulation.
• Macrolide antibiotics (e.g., erythromycin): may increase itraconazole levels.
• Antacids containing aluminum or magnesium: reduce absorption, separate dosing.
• Antihistamines (e.g., cetirizine): may increase plasma concentrations modestly.