Therapeutic drug monitoring of HIV-protease inhibitors to assess noncompliance.

Objective: To determine plasma concentration ratio limits (CORALS) for HIV-protease inhibitors outside of which random plasma concentrations reflect partial compliance or noncompliance. In the absence of a gold standard for measuring compliance and to avoid complex techniques, measuring plasma concentrations may be an objective and easy way to check noncompliance.

Methods: Pharmacokinetic curves after observed ingestion were recorded in patients on steady-state indinavir 800 mg TID (n = 22), ritonavir 400 mg/saquinavir 400 mg BID (n = 22, ritonavir; n = 17, saquinavir hard-gel capsules), or nelfinavir 750 mg TID (n = 4) or 1250 mg BID (n = 4).