Drug Interaction Report

The coadministration of probenecid and acyclovir may result in elevated plasma concentrations of acyclovir. In 3 subjects with normal renal function, probenecid 1 gram increased the area under the plasma concentration-time curve and terminal plasma half-life of acyclovir (5 mg/kg intravenously) by an average of 40% and 18%, respectively. Renal clearance decreased an average of 32%. The mechanism is competitive inhibition of acyclovir renal tubular secretion by probenecid. Although this interaction is unlikely to be of clinical significance, caution may be advisable if acyclovir is used concomitantly with probenecid.