Adults

For most infections: 500 mg to 1 g intravenously every 8 hours, depending on the severity and type of infection. For bacterial meningitis or severe infections: 2 g intravenously every 8 hours.

Elderly

Dosage adjustment may be necessary based on renal function. No specific dose adjustment solely based on age for normal renal function.

Renal_impairment

Requires significant dose reduction based on creatinine clearance (e.g., CrCl 26-50 mL/min: 1 g every 12 hours; CrCl 10-25 mL/min: 500 mg every 12 hours; CrCl <10 mL/min: 500 mg every 24 hours). Hemodialysis patients require a supplementary dose after each dialysis session.

Onset

Rapid, typically within minutes of administration.

Excretion

Primarily excreted unchanged by the kidneys (approximately 70% as unchanged drug within 12 hours).

Half life

Approximately 1 hour in adults with normal renal function.

Absorption

Administered intravenously, meropenem is 100% bioavailable.

Metabolism

Undergoes limited metabolism; primarily hydrolyzed by dehydropeptidase-I (which is inhibited by cilastatin, though meropenem is stable to DHP-I).

Probenecid

Probenecid competes with meropenem for active tubular secretion, leading to increased plasma concentrations and prolonged half-life of meropenem. Co-administration should be avoided unless the benefit outweighs the risk.

Valproic acid

Concomitant administration with meropenem may reduce valproic acid plasma concentrations below the therapeutic range, leading to an increased risk of seizures. Co-administration is generally not recommended.