valacyclovir and Cimetidine Interactions

Interactions between valacyclovir and Cimetidine (cimetidine)

cimetidine and valacyclovir (Minor Drug-Drug)

Cimetidine may increase the serum concentration of acyclovir. The mechanism is competitive inhibition of the renal tubular secretion of acyclovir. Initial dosage adjustments usually are not necessary. Patients should, however, be monitored for acyclovir-related toxicities. Also, cimetidine reduces the rate at which valacyclovir is converted to acyclovir. The extent of conversion is unaffected, and this interaction is not considered to be clinically significant.