Purpose of review: Therapeutic drug monitoring is frequently used in several European countries, and international guidelines recommend it in selected cases. We discuss the main arguments for and against therapeutic drug monitoring in HIV infection.
Recent findings: Accumulating evidence favours the use of therapeutic drug monitoring in the management of drug concentration-related toxicities. Interindividual variability in the pharmacokinetics of antiretroviral drugs is at least partially caused by genetic polymorphisms. Additionally, body weight, sex and ethnicity have been identified as independent predictors of pharmacokinetics. Several studies have revealed subtherapeutic drug concentrations in children who were treated in accordance with the label information, which is in favour of therapeutic drug monitoring in children. The inhibitory quotient concept has been further explored, but more work is needed to justify full implementation into routine clinical practice. A limitation of therapeutic drug monitoring is the significant intraindividual variability in protease inhibitor concentrations. Furthermore, there is a lack of sufficiently powered randomized controlled trials that assess the use of routine therapeutic drug monitoring for current first-line antiretroviral drugs.
Summary: Although routine therapeutic drug monitoring cannot be recommended for current first-line antiretroviral drugs, there are many frequently encountered clinical situations in which therapeutic drug monitoring provides valuable information.