TABLE 1.

Identified areas of needed research related to drug interactions

Drug interaction studies opioid therapies (methadone, buprenorphine) and new ARV (eg, maraviroc, etravirine) and medications currently in development	Studies designed to illuminate the role of hepatic enzymes and/or P-glycoprotein in observed interactions
Neuroimaging studies to determine the mechanism for lack of opiate withdrawal in buprenorphine-maintained individuals versus methadone-maintained individuals receiving medications that lower serum concentrations of these opioids	Develop new or validate current in vitro/in vivo models to study drug–drug interactions
Study of mechanisms of induction of drug-metabolizing enzymes	Expand drug interaction studies to include other illicit (cocaine, methamphetamine, cannabis, heroin) and licit drugs (alcohol, nicotine products) with medications frequently utilized by substance-abusing populations (ARV, HCV medications, TB medications, psychotropics)
Studies of methodological issues in drug interactions studies	Development of protocols for the management of drug interactions
Study of genetic factors associated with drug interactions	Design of simplified protocols for special populations that may have difficulty with standard drug interaction paradigms
Utilization of clinical trial networks to undertake greater numbers of drug interaction studies	Study the impact of pharmacokinetic and pharmacodynamic interactions on the therapeutic efficacy of drugs; develop guidelines for cutoffs that would trigger discontinuation of a drug and substitution of another