Adults

The usual adult dose is 200 mg every 12 hours or 400 mg once daily, as directed by a physician. Treatment duration typically ranges from 7-14 days depending on the type and severity of infection.

Elderly

No specific dosage adjustment is generally required for elderly patients with normal renal function. However, renal function should be assessed before initiating therapy.

Renal_impairment

For patients with creatinine clearance between 21-60 mL/min, the dose should be reduced to 300 mg daily. For creatinine clearance less than 20 mL/min, the dose should be reduced to 200 mg daily. Patients on chronic ambulatory peritoneal dialysis (CAPD) or hemodialysis should also receive 200 mg daily.

Onset

Peak plasma concentrations are typically achieved within 2-6 hours after oral administration.

Excretion

The main route of excretion is renal, with approximately 50% of an absorbed dose being excreted unchanged in the urine over 24 hours. Some non-renal elimination also occurs.

Half life

The plasma elimination half-life averages 3-4 hours, though it can be longer in patients with renal impairment.

Absorption

Approximately 40-50% of an oral dose is absorbed. Food may delay the time to peak concentration (Tmax) but does not significantly affect the extent of absorption (AUC).

Metabolism

Cefixime undergoes very limited hepatic metabolism; it is primarily excreted as the unchanged drug.

Nifedipine

Concomitant administration may increase the bioavailability of cefixime, potentially leading to higher plasma concentrations.

Carbamazepine

Elevated carbamazepine levels have been reported when administered concomitantly with cefixime. Therapeutic drug monitoring and dosage adjustment of carbamazepine may be appropriate.

Warfarin and other anticoagulants

Concurrent use may increase prothrombin time (PT) and INR, with or without clinical bleeding. Close monitoring of coagulation parameters is advised, and anticoagulant dose adjustment may be necessary.