Adults

Standard adult dose for most infections: 250 mg to 500 mg every 8 hours, or 500 mg to 875 mg every 12 hours, depending on the severity and type of infection. For severe infections, doses may be increased. For H. pylori eradication, specific combination regimens are used.

Elderly

No specific dose adjustment required based solely on age, but renal function should be considered, as elderly patients may have reduced renal clearance.

Renal_impairment

For creatinine clearance <30 mL/min, dose adjustment is necessary. For severe renal impairment (<10 mL/min), dosage should be reduced to 250 mg every 12-24 hours.

Onset

Clinical effects usually within 30-60 minutes.

Excretion

Primarily excreted unchanged by the kidneys via tubular secretion and glomerular filtration. Approximately 60-80% of an oral dose is excreted in the urine within 6-8 hours.

Half life

Approximately 1-1.5 hours in adults with normal renal function. This duration increases significantly in patients with impaired renal function.

Absorption

Rapidly and well-absorbed from the gastrointestinal tract, with approximately 70-90% bioavailability. Peak plasma concentrations are achieved in about 1-2 hours.

Metabolism

A small proportion (10-25%) is metabolized in the liver to inactive penicilloic acid.

Probenecid

Decreases renal tubular secretion of amoxicillin, resulting in increased and prolonged plasma levels of amoxicillin.

Allopurinol

Increased incidence of rash, particularly in patients with hyperuricemia.

Methotrexate

Reduced renal tubular secretion of methotrexate, potentially leading to increased methotrexate toxicity.

Oral Contraceptives

Reduced efficacy of oral contraceptives (rarely reported).

Warfarin and other oral anticoagulants

Increased risk of bleeding due to potential enhancement of anticoagulant effect.