Background: Pharmacokinetic interactions complicate and potentially compromise the use of antiretroviral and other HIV therapeutic agents in patients with HIV disease. This may be particularly so among those receiving treatment for substance abuse.
Objective: We describe seven cases of opiate withdrawal among patients receiving chronic methadone maintenance therapy following initiation of therapy with the non-nucleoside reverse transcriptase inhibitor, nevirapine.
Design: Retrospective chart review.
Results: In all seven patients, due to the lack of prior information regarding a significant pharmacokinetic interaction between these agents, the possibility of opiate withdrawal was not anticipated. Three patients, for whom methadone levels were available at the time of development of opiate withdrawal symptoms, had subtherapeutic methadone levels. In each case, a marked escalation in methadone dose was required to counteract the development of withdrawal symptoms and allow continuation of antiretroviral therapy. Three patients continued nevirapine with methadone administered at an increased dose; however, four chose to discontinue nevirapine.
Conclusion: To maximize HIV therapeutic benefit among opiate users, information is needed about pharmacokinetic interactions between antiretrovirals and therapies for substance abuse.