Systematic Approach to Managing Drug Interactions
Obtain complete medication history
- include Rx, OTC, herbals, vitamins, recreational
- categorize drugs by pharmacokinetic/dynamic properties
Identify potential conflicting combinations
- different absorption requirements
- opposing/overlapping metabolic characteristics
- CYP450 substrate, induction/inhibition
Notes:
- With new therapeutic agents continually being developed, keeping abreast of potential interactions is extremely challenging. Many antiretroviral agents may be administered via clinical trials or compassionate access programs before comprehensive interaction studies are conducted. Consequently, patients may receive combinations of drugs for which pharmacokinetic interaction data are not available.
- In such situations, familiarity with the basic pharmacokinetic and pharmacodynamic characteristics of the involved agents may help practitioners predict the likelihood of interactions.
- All protease inhibitors and NNRTIs are substrates of the cytochrome P450 system, and also possess enzyme inhibiting and/or inducing properties. Careful consideration of such information is crucial in order to anticipate possible interactions, and to optimize therapeutic efficacy and minimize drug toxicity.