lamivudine and Trimpex Interactions

Interactions between lamivudine and Trimpex (trimethoprim)

trimethoprim and lamivudine (Minor Drug-Drug)

In a study with 14 HIV-positive patients, coadministration of trimethoprim/sulfamethoxazole (TMP/SMX DS once a day for 5 days) and lamivudine (300 mg single dose on day 5) resulted in a mean decrease of 35% in lamivudine renal clearance and a mean increase of 43% in lamivudine area under the plasma concentration-time curve. The mechanism of interaction is thought to be competitive inhibition of tubular secretion by trimethoprim. Lamivudine did not affect the pharmacokinetic profile of TMP/SMX. Given the favorable safety profile of lamivudine, this interaction is unlikely to be of clinical significance. However, the effect of higher dosages of TMP/SMX on lamivudine pharmacokinetics has not been investigated.