Nonprescribed use of tranquilizers and use of other drugs among Brazilian students.

OBJECTIVES To describe patterns of nonprescribed use of tranquilizers by students aged 10 to 18 years and assess the sociodemographic characteristics of these adolescents and their use of other substances. METHODS A randomized and stratified sample of 47,979 students from state and private schools of the 27 Brazilian state capitals completed a self-report questionnaire. Poisson regression was used to estimate the associations between tranquilizer use and sociodemographic factors, as well as the use of other psychotropic substances. RESULTS The lifetime prevalence of nonprescribed use of tranquilizers was 3.9%. Use was most common among girls, wealthier adolescents, and those from private schools. An association was found between use of tranquilizers and lifetime use of alcohol (prevalence ratio [PR] = 3.15; 95% confidence intervals [95%CI] 2.58-3.85), tobacco (PR = 2.61; 95%CI 2.31-2.95), illicit drugs (PR = 3.70; 95%CI 3.19-4.29), and other prescription drugs (PR = 7.03; 95%CI 6.18-7.99). As the number of substances adolescents reported having used increased, so did the nonprescribed use of tranquilizers. CONCLUSIONS Nonprescribed use of tranquilizers by adolescents might indicate the use of other substances, including high-risk combinations such as tranquilizers and alcohol. The risks of this association should be addressed during the early stages of drug prevention programs.