Adults

200-400 mg daily, given as a single dose or in two divided doses for 7-14 days depending on the infection. For uncomplicated gonorrhea, a single 400 mg dose.

Elderly

No dosage adjustment needed unless renal function is severely impaired.

Renal_impairment

Dosage reduction is recommended for patients with creatinine clearance less than 30 ml/min. For CrCl 21-60 ml/min, standard dose once daily. For CrCl <20 ml/min, 200 mg once daily.

Onset

Peak plasma concentrations are achieved within 2-6 hours.

Excretion

Primarily excreted unchanged in the urine (about 50% of absorbed dose) and also via biliary excretion.

Half life

Plasma half-life is typically 3 to 4 hours.

Absorption

Approximately 40-50% absorbed orally, food does not significantly alter absorption.

Metabolism

Not extensively metabolized; approximately 10% appears to be metabolized.

Carbamazepine

Increased carbamazepine levels when co-administered. Monitor carbamazepine levels.

Oral Contraceptives

Potential for reduced efficacy of oral contraceptives (though clinical significance is debated).

Aminoglycosides / Loop Diuretics

May increase nephrotoxicity (rare).

Oral Anticoagulants (e.g., Warfarin)

Increased prothrombin time (INR) and bleeding risk. Monitor INR closely.