Adults

Adults: Typically 800 mg to 1200 mg orally daily, in two divided doses, depending on body weight and HCV genotype, in combination with pegylated interferon alpha or direct-acting antivirals. For patients weighing less than 75 kg, 1000 mg/day; for patients weighing 75 kg or more, 1200 mg/day.

Elderly

Elderly: No specific dose adjustment solely based on age. Dosage should be adjusted based on renal function if impaired.

Renal_impairment

Renal impairment: For creatinine clearance <50 mL/min, dosage must be significantly reduced or contraindicated. Consult prescribing information for specific guidelines.

Onset

Viral load reduction typically observed within the first 4 weeks of treatment.

Excretion

Primarily excreted renally as unchanged drug and metabolites. Approximately 60-70% of a dose is excreted in urine and 10% in feces.

Half life

Plasma half-life is approximately 120-200 hours (5-8 days), with an intracellular half-life in red blood cells of 16-20 days.

Absorption

Rapidly absorbed after oral administration, with peak plasma concentrations reached in 1-2 hours. Bioavailability is approximately 45-65%.

Metabolism

Metabolized by reversible phosphorylation and cleavage to 1,2,4-triazole-3-carboxamide. Not extensively metabolized by the cytochrome P450 system.

Didanosine

Concomitant use with didanosine is not recommended due to increased risk of mitochondrial toxicity, which can lead to lactic acidosis and pancreatitis.

Azathioprine

Increased risk of myelosuppression (e.g., severe neutropenia) when co-administered with azathioprine, especially in patients with renal impairment.