Benzodiazepines and driving

• there is evidence that patients taking benzodiazepines have an increased risk of being involved in a road traffic accident (RTA)
• a study used a record-linkage database to examine the association of prescription of psychotropic drugs and RTA. Drugs examined were tricyclic antidepressants; selective serotonin re-uptake inhibitors; benzodiazepines and other traquillisers
• the prescriptions for benzodiazepines were associated with an increased risk of involvement with an RTA. The odds ratio was 1.62 with a 95% confidence interval of 1.24-2.12. There was insufficient evidence of an association with other psychotropic drugs
  
  
• the DVLA note that (2)
  • Medication effects
    • It is an offence to drive or attempt to drive while unfit because of alcohol and/or drug use - and driving laws do not distinguish between illegal and prescribed drugs
    • drivers taking prescribed drugs subject to the drug-driving legislation will need to be advised to carry confirmation that these were prescribed by a registered medical practitioner.
    • some prescription and over-the-counter medicines can affect driving skills through drowsiness, impaired judgement and other effects.
    • prescribers and dispensers should consider any risk of medications, single or combined, in terms of driving - and advise patients accordingly.
  • without providing an exhaustive list, the following drug groups require consideration:
    • benzodiazepines - these may cause sufficient sedation to make driving unsafe
      • benzodiazepines are the psychotropic medications most likely to impair driving performance - the long-acting compounds in particular- and alcohol will potentiate effects
  • antidepressants - sedating tricyclics have a greater propensity to impair driving than SSRIs, which are less sedating. Advice for individual driving safety should be considered carefully for all antidepressants
  • antipsychotics - many of these drugs will have some degree of sedating side effect via action on central dopaminergic receptors. Older drugs (chlorpromazine, for example) are highly sedating due to effects on cholinergic and histamine receptors. Newer drugs (olanzapine or quetiapine, for example) may also be sedating; others less so (risperidone, ziprasidone or aripiprazole, for example)
  • opioids - cognitive performance may be reduced with these, especially at the start of use, but neuro-adaptation is established in most cases. Driving impairment is possible because of the persistent miotic effects of these drugs on vision

Group 1 entitlement with respect to misuse or dependence on benzodiazepines:

• Must not drive and must notify the DVLA with persistent misuse or dependence.
• Medical enquiry confirming the problem will result in licence being refused or revoked for a minimum of 1 year, which must be free of misuse or dependence.
• Relicensing may require an independent medical assessment and urine screen arranged by the DVLA.

Notes:

• benzodiazepines (2)
  • the non-prescribed use of these agents and/or the use of a supratherapeutic dosage outside BNF guidelines constitutes persistent misuse or dependence for licensing purposes- whether in a programme of substance withdrawal or maintenance, or otherwise
  • the prescribed use of these drugs at the therapeutic doses listed in the BNF, without evidence of impairment, does not amount to persistent misuse or dependence for licensing purposes (albeit, clinical dependence may exist).

Please consult the DVLA website for up to date guidance.

Reference:

• (1) Lancet 1998; 302: 1331-1336.
• (2) DVLA (March 2019). For Medical Practitioners. At a glance guide to the medical standards for fitness to drive.