Association between cigarette smoking and plasma concentration of efavirenz: a systematic review

Introduction: Statistics show that prevalence of smokers is higher among human immunodeficiency virus-positive patients. Efavirenz is still widely used in resource-limited setting around the world. In view of overlapping metabolic pathways between cigarette smoking and efavirenz, it is suggested that poorer treatment outcome among smokers with HIV might be in some way associated with abnormal plasma concentration of efavirenz. Material and methods: Comprehensive search of the literature was performed using PubMed Central, PubMed/Medline, Cochrane Review, Science Direct, Springer Link, Oxford Academic, and Lippincott Williams & Wilkins journals. Results: A total of 157 articles were chosen, out of which 8 met eligibility criteria and were reviewed. Lower efavirenz plasma concentration were found in 5 articles, where genetic polymorphism was the major significant co-variate. Only 2 studies described smoking as significantly associated with lower efavirenz plasma concentration. Conclusions: Smoking was found to be associated with a lower efavirenz plasma concentration, especially in population with genetic polymorphism. Future research is required with better methodological design, and subjects with genetic polymorphism need to be excluded, to further investigate the causal relationship of smoking status and efavirenz plasma concentration. retrospective cohort study, case-control study, and pharmacokinetic study.