Der ses ingen klinisk relevant interaktion, når fosamprenavir 700 mg 2 gange daglig og ritonavir 100 mg 2 gange daglig anvendes samtidig med efavirens (600 mg 1 gang daglig).
Efavirenz: there was no clinically relevant interaction when fosamprenavir 700 mg twice daily and ritonavir 100 mg twice daily was used concurrently with efavirenz (600 mg once daily).