Residual effects and skills related to driving after a single oral administration of diazepam, medazepam or lorazepam.

Abstract

1 Psychomotor skills and visual functions related to driving were measured double-blind cross-over in ten healthy volunteers before, and 1, 3, 5 and 7 h after a single oral administration of diazepam (10 mg), medazepam (15 mg) or lorazepam (2.5 mg). The late effects of lorazepam were tested in seven other subjects 12 and 24 h after the administration. 2 Lorazepam impaired almost all the measured skills more (P < 0.05 to 0.001) than diazepam, medazepam or the placebo. The lorazepam impairment of reactive skills and flicker fusion discrimination remained statistically significant (P < 0.05) for as long as 12 h. Medazepam impaired only reactive skills and flicker fusion, the latter remaining impaired (P < 0.05) for as long as 5 h after the administration. The magnitude and duration of the effects of diazepam were intermediate between those of lorazepam and medazepam. Diazepam impaired perceptual speed and reactive and co-ordinative skills as well as flicker fusion discrimination and visual parameters related to driving. Slight impairments in performance were measurable for up to 5 h after administration but at 7 h the results resembled those measured after the placebo. 3 The lack of alterations in adaptation to darkness, sensitivity to brightness or visual discrimination ability in bright counterlight at a time when flicker fusion discrimination was severely depressed suggests that an impaired ability to discriminate flickering light is of no or little clinical significance to driving ability. 4 It is concluded that patients receiving a 2.5 mg dose of lorazepam should not drive or operate machinery for 24 h after the administration. After diazepam (10 mg) or medazepam (15 mg) patients should refrain from driving or participating in skilled performances for only 5 to 7 hours.

The effects of clobazam and lorazepam on aspects of psychomotor performance and car handling ability.

“…It has marked sedative properties (Seppala, Kortilla, Hakkinen & Linnoila, 1976) making it clinically useful as a hypnotic and surgical premedication (Norris & Wallace, 1971;Globus, Phoebus, Humphries, Boyd, Gaffney & Gaffney, et al, 1974;Straughan, 1979). At doses between 1-4 mg lorazepam has been shown to impair performance on 0306-5251/80/080145-06 $01.00 analogues ofcar driving (Sappala et al, 1976), reaction time (Harry & Richards, 1972;Turner, 1973), flicker fusion frequency (Hedges, Turner & Harry, 1971;Turner, 1973;Farhoumand, Harrison, Pare, Turner & Wynn, 1979) and sensori-motor coordination (Bell, Dickie, Stewart-Jones & Turner, 1973 …”

Enhancement of GABAergic Activity: Neuropharmacological Effects of Benzodiazepines and Therapeutic Use in Anesthesiology

“…In healthy volunteers, peak plasma concentration after ingestion of a 10-mg diazepam tablet is 300 ng/ml (Seppälä et al, 1976), and time to peak plasma concentration is approximately 60 min (Gamble et al, 1976). An injection of 0.15 mg/kg i.v.…”

Psychomotor function and psychoactive drugs.

“…Linnoila & Hakkinen (1974) found that diazepam 10 mg caused professional drivers to 'collide' significantly more frequently than when treated with placebo, on a car driving simulator. On a set of skills related to car driving Seppala, Korttila, Hakkinen & Linnoila (1976) found that diazepam 10 mg, medazepam 15 mg and lorazepam 2.5 mg all produced significant impairments of one or more experimental measures when compared to placebo. Korttila (1977) showed lack of impairment of driving related skills following intramuscular injection of prilocaine or mepivacaine but found impairments following lidocaine, bupivacaine and etidocaine.…”