Actions and interactions with alcohol of drugs on psychomotor skills: comparison of diazepam and gamma-hydroxybutyric acid.

Effects of gamma-hydroxybutyric acid (GOBA) on psychomotor skills related to driving were studied in healthy student volunteers. The effects of oral GOBA 1.0 and 2.0 g, alone or in combination with 0.5 g/kg of ethyl alcohol, were compared in double-blind cross-over trials against oral diazepam 10 mg (D), alcohol 0.5 g/kg, and lactose placebo. Reactive and co-ordinative skills, attention, flicker fusion, proprioception, nystagmus, Maddox wing, and subjective estimations were included. The first single-dose trial with 12 volunteers revealed that neither GOBA 1.0 g nor D modified attention. D impaired reactive skills whilst co-ordinative skills remained largely uninfluenced by D or GOBA. Both D and GOBA impaired leg proprioception. Only D was experienced as a sedative drug. In the second trial with 12 volunteers, GOBA 1.0 g slightly increased reaction mistakes whereas GOBA 2.0 g next day did not. Either dose of GOBA was ineffective on co-ordinative skills, critical flicker fusion frequency, and proprioception. Alcohol alone (0.41 +/- 0.047 mg/ml) improved rather than impaired skills. GOBA 1.0 g + alcohol (0.36 +/- 0.027 mg/ml) impaired reactive skills more than GOBA 2.0 g did but no potentiation was seen. D impaired reactive and co-ordinative skills and flicker fusion. When D was given on two consecutive days, some tachyphylaxis to the D response was seen on co-ordinative skills but not on reactive skills or flicker fusion. It is concluded that in the recommended anxiolytic doses used GOBA neither deteriorates driving skills nor importantly increases the effects of low doses of alcohol.