PsychoTropicalResearch, serotonin and serotonin syndrome research.
Accidents - RTAs
Accidents - RTAs
Date Created: 22/03/1999 Last Modified: 19/01/2002 Last Checked: 04/01/2003
The risk of road traffic accidents (RTAs) with sedative tricyclic antidepressants appears to be increased in relation to dose, and probably the sedative potency of the particular drug. Doses of the sedative drug amitriptyline of more than 125 mg per day may increase the risk of an RTA (involving significant injury) by about five times; however, whether therapeutic doses of less sedative TCAs, such as nortriptyline or desipramine, would be associated with a significantly increased risk is unknown and perhaps less likely. The new ‘NRI’, reboxetine, appears much less liable to cause psychomotor impairment; one might reasonably suppose that the less sedative TCAs (particularly desipramine and lofepramine) would therefore be closer to reboxetine than to amitriptyline.
See the note on 'Driving cars and machines, Drug effects on' for an analysis of the effects of specific drugs on driving skills in experiments on normal subjects; note however that we do not know how to extrapolate from such work to a clinical situation. That represents a different question, which is; what is the difference between an ill person on no treatment driving and an ill person with medication driving? In view of the lesson from falls and SSRIs it would be naive to make presumptions (see Accidents Falls)
The risk with benzodiazepines probably is increased; especially in older persons and if alcohol is also present. This appears to apply particularly for long-half-life benzodiazepines. Users of long-half-life benzodiazepines (and zopiclone) may be advised that their ability to drive is probably somewhat impaired and that their accident risk may be about 2-3 times higher. With any drug the risk appears likely to be higher in the first days of treatment, or after a dose increase.
It may be pertinent to appreciate that we are unable, at present, to make accurate statements about precise risk changes in specific groups. When, and by whom, a decision to revoke an individuals licence might be made is a grey area; the advice doctors give should be tempered with caution and take due note of other risk factors (eg see below).
I think a reasonable approach is to recognise patients' responsibility to act on advice; up to date information on the evidence available is contained here in 'Psychopharmacology update notes' and this may be passed on to patients as appropriate. There is good reason to suppose that if doctors are forced to adopt the role of 'policeman' in this area that patients will quickly learn to avoid them and / or lie to them. That damages the central and vital trust in the therapeutic relationship.
Most regulatory authorities have not bitten the bullet on this one yet. One imagines it would be political dynamite; what 'Sir Humphrey' would describe to the minister as a 'courageous stance', if the minister were to suggest advocating tighter regulations! (for those not familiar with 'Yes Minister' a 'courageous stance' is one that will loose you the next election).
There are various other risk behaviours to consider; evidence indicates that using a phone (even a 'hands-off' one, see Redelmeier et al) increases accident risk by four times, having a fluffy toy dangling from the drivers mirror by six times and wearing a hat inside a vehicle by ten times (that is doubled again if the vehicle is a 'Volvo').
Sorry, that is not quite all true, the last two statements are not supported by any formal evidence (although they may well be true) !
All text ©Dr Ken Gillman MRC Psych - PsychoTropical Research®
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