Frågedatum: 2004-06-28
RELIS database 2004; id.nr. 20887, DRUGLINE
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Could zopiclone cause residual sedation thirteen hours after intake?/nA bus driver successfully use



Fråga: Could zopiclone cause residual sedation thirteen hours after intake? A bus driver successfully uses his mother´s zopiclone (Imovane) to treat a sleep disturbance characterised by reawakening only half an hour after falling asleep and wants a prescription of the drug. He goes to bed at one AM and starts his shift thirteen hours later, at two PM.

Sammanfattning: Residual effects of zopiclone have been demonstrated 10-11 hours after intake and could probably remain after 13 hours. If pharmacological treatment is deemed necessary, zopiclone is therefore not an ideal choice in this patient. A hypnotic with shorter half-life, eg zolpidem or zaleplon, could be a better choice provided that adequate clinical effect is achieved.

Svar: Zopiclone has a half-life of 4-5 hours. Hence, complete elimination could not be expected within thirteen hours (1).

Three studies investigating the residual effects of zopiclone on driving performance were identified (2,3,4). In all three studies, the tests were performed 10-11 hours after a single 7.5 mg dose. In two studies, zopiclone had significant detrimental effects on driving performance, including vehicle positioning and reaction times (2,3). The residual effects of zopiclone on driving performance were significantly larger compared to the acute effects of ethanol in a blood concentration of 0.05 percent (2). The third study failed to show any late effects of zopiclone. However, the small size of this study (ten subjects) raises concerns about its statistical power (4). Two hypnotics with shorter half-lives, zaleplon (2) and zolpidem (3,4), had no residual effects in these studies.

The association between zopiclone use and car accidents has been addressed in an epidemiological study (5). The risk of having a traffic accident (as a driver) when exposed to zopiclone (according to prescription data) was four times higher than the risk of having an accident while unexposed. Although this "case-crossover" design reduces the bias risk inherent in ordinary case-control studies, there is still an obvious risk of confounding by indication (sleep disturbance). Hence, the results should be interpreted with caution.

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