Background Opiates could impair psychomotor performance, and driving under the influence of opiates is associated with increased accident risk. The aim of the study was: i) to determine the prevalence of opiates in Spanish drivers; and ii) to explore opiate drug usage (heroin, morphine, codeine and methadone), alone or in combination with other drugs.

Methods The 2008/9 DRUID database regarding Spain was used, including information on 3302 drivers. All drivers included in the study provided a saliva sample and mass-chromatographic analysis was provided in all cases. To determine prevalence, the sample was weighted according to traffic intensity and, for positive cases, DRUID project cutoffs were applied. To explore opiate use the sample was used unweighted and the detection of each substance was considered a positive result.

Results The prevalence of opiates in Spanish drivers was 0.5% (95% CI: = [0.3–0.8]). Opiates, either alone or together with other drugs, were detected in 64 drivers. The average age (±SD) was 35.53 ± 11.72 years and the majority of the cases were men (79.7%). No case of morphine as medicinal use was observed. The specific metabolite of heroin 6-acetyl morphine (6-AM) was detected in the saliva of 34 drivers: in 8 cases alone, in 7 cases with methadone, multiple substance use being the rule. Codeine was detected in 26 drivers (in 10 drivers alone) and methadone in 24 drivers (in 10 drivers alone). Polydrug use was common in opiate user drivers (56.25%). The most frequent non opiate drugs were cocaine (n = 32), THC (n = 14) and benzodiazepines (n = 7).

Conclusions Driving with the presence of opiates is relatively infrequent. Polydrug use is common among Spanish drivers who are opiate users. Only 40% of methadone positive cases (likely on methadone maintenance programs) were using this substance alone.

Supported by a grant from the Instituto de Salud Carlos III, Redes Temáticas de Investigación Cooperativa, Red de Trastornos Adictivos RD12/0028/00212