Adults

Typical dosage ranges from 100 mg once daily to 200 mg twice daily, depending on the specific infection and severity. For onychomycosis, pulse therapy (200 mg twice daily for 1 week/month for 2-3 months) or continuous therapy (200 mg once daily for 3-6 months) may be used.

Elderly

Use with caution; dosage adjustment may be required based on overall health, renal, or hepatic function. Consider lower starting doses.

Renal_impairment

Use with caution. Dosage reduction or extended dosing intervals may be necessary, especially in severe renal impairment (CrCl <30 mL/min). Monitor plasma concentrations if possible.

Hepatic_impairment

Use with caution. Dosage reduction may be necessary in patients with hepatic impairment. Monitor liver function closely.

Onset

Therapeutic effects may take days to weeks to manifest, depending on the infection type and location.

Excretion

Primarily excreted as inactive metabolites in urine (approximately 35%) and feces (approximately 54%). Only about 0.03% of an oral dose is excreted unchanged in urine.

Half life

Approximately 20-30 hours for the parent drug (itraconazole) and 30-40 hours for its active metabolite (hydroxyitraconazole).

Absorption

Well absorbed from the gastrointestinal tract when taken with a full meal. Bioavailability is enhanced by food and gastric acidity. Peak plasma concentrations are reached 2-5 hours after oral administration.

Metabolism

Extensively metabolized in the liver, primarily by the cytochrome P450 3A4 (CYP3A4) enzyme system, into several metabolites, including the active metabolite hydroxyitraconazole.

Oral anticoagulants (e.g., warfarin)

Increased anticoagulant effect, leading to a higher risk of bleeding. Close monitoring of INR is required.

Proton pump inhibitors/H2 blockers/Antacids

Reduced gastric acidity can impair itraconazole absorption. Administer at least 2 hours before or 2 hours after antacids/H2 blockers. Consider taking itraconazole capsules with an acidic beverage (e.g., cola) if using acid-reducing agents.

CYP3A4 inhibitors (e.g., ritonavir, clarithromycin)

Can significantly increase itraconazole plasma concentrations, potentially leading to increased adverse effects. Dose reduction of itraconazole may be required.

CYP3A4 inducers (e.g., rifampicin, phenytoin, carbamazepine)

Can significantly decrease itraconazole plasma concentrations, reducing its efficacy. Concomitant use should generally be avoided.

Calcium channel blockers (e.g., dihydropyridines, verapamil)

Increased risk of edema, and itraconazole levels may also be affected. Monitor closely.

HMG-CoA reductase inhibitors (e.g., simvastatin, lovastatin)

Contraindicated due to increased risk of myopathy and rhabdomyolysis.