Adults

Usual adult dose is 250-500 mg every 6 hours, preferably administered 1 hour before meals. For severe infections, the dose may be increased up to 1 g every 6 hours.

Elderly

Similar to adult dosage, but caution and dose reduction may be necessary in severe renal impairment.

Renal_impairment

In severe renal impairment (creatinine clearance < 10 mL/min), a dose reduction or increased dosing interval (e.g., 250 mg every 8-12 hours) is recommended to avoid accumulation.

Onset

Within 30-60 minutes after oral administration.

Excretion

Primarily excreted unchanged in the urine (about 65-70% of a dose) through glomerular filtration and tubular secretion. A small amount is excreted in bile.

Half life

Approximately 0.5 to 1.5 hours in individuals with normal renal function.

Absorption

Well absorbed orally, though absorption is reduced by food. Peak plasma concentrations are achieved in approximately 1-2 hours.

Metabolism

Partially metabolized in the liver to inactive metabolites.

Warfarin

Flucloxacillin may increase the anticoagulant effect of warfarin, requiring close monitoring of INR and possible dose adjustment of warfarin.

Probenecid

Concomitant administration of probenecid delays the renal excretion of flucloxacillin, leading to increased and prolonged plasma concentrations.

Methotrexate

May increase methotrexate toxicity by reducing its renal clearance.

Oral Contraceptives

The efficacy of oral contraceptives may be reduced, although this interaction is less commonly reported with flucloxacillin compared to broad-spectrum antibiotics.