Fosamprenavir/ritonavir plus tenofovir does not affect amprenavir pharmacokinetics: no effect of tenofovir.

The effect of tenofovir disoproxil fumarate (TDF) in combination with two boosted fosamprenavir regimens on amprenavir pharmacokinetic parameters was assessed in this prospective phase I crossover study with 30 healthy volunteers. The co-administration of TDF 300 mg once a day with fosamprenavir/ritonavir 1400/200 mg or 1400/100 mg once a day has no effect on the pharmacokinetics of amprenavir and results in non-significant increases of ritonavir pharmacokinetic parameters, suggesting that no dose modification is necessary when combining fosamprenavir/ritonavir with TDF.