Acute effect of antipyretic analgesics, alone or in combination with alcohol, on human psychomotor skills related to driving.

1 The effect of acetylsalicylic acid (1 g), indomethacin (50 mg), and phenylbutazone (200 mg) on psychomotor skills was examined double blind on 180 volunteer students. Ninety students received ethyl alcohol (0.5 g/kg) and 90 subjects an equal volume of placebo drink in combination with the drugs. 2 Psychomotor skills were measured with a choice reaction test, two co-ordination tests, and a divided attention test, having correlation with traffic behaviour. The subjects assessed their feelings of performance by means of a rating scale. The tests were done 30, 90 and 150 min after the administration of the agents. 3 Acetylsalicylic acid proved inactive whereas both indomethacin and phenylbutazone impaired eye-hand co-ordination and divided attention. Acetylsalicylic acid did not interact with alcohol to a measurable extent whereas indomethacin in combination with alcohol proved less harmful than without it. The deleterious effects of phenylbutazone and alcohol were additive. 4 An impairment of psychomotor skills related to driving by indomethacin and phenylbutazone should be considered when prescribing these drugs to active out-patients.