Acute and subchronic effects of amitriptyline 25 mg on actual driving in
chronic neuropathic pain patients
Dieuwke S. Veldhuijzen1*,
Albert J. van Wijck2,
Joris Vester3,
J. Leon Kenemans4,
Cor J. Kalkman2,
Berend Olivier3,
Edmund Volkerts3
1 Utrecht Institute for Pharmaceutical Sciences and Rudolf Magnus
Institute of Neuroscience, Department of Psychopharmacology, Utrecht University,
Utrecht, The Netherlands. Pain Clinic, Department of Anaesthesiology, University
Medical Centre Utrecht, Utrecht, The Netherlands
2 Pain Clinic, Department of Anaesthesiology, University Medical Centre
Utrecht, Utrecht, The Netherlands
3 Utrecht Institute for Pharmaceutical Sciences and Rudolf Magnus
Institute of Neuroscience, Department of Psychopharmacology, Utrecht University,
Utrecht, The Netherlands
4 Utrecht Institute for Pharmaceutical Sciences and Rudolf Magnus
Institute of Neuroscience, Department of Psychopharmacology, Utrecht University,
Utrecht, The Netherlands. Helmholtz Research Institute, Department of
Psychonomics, Utrecht University, Utrecht, The Netherlands
* To whom correspondence should be addressed.
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Abstract |
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The acute and subchronic effects of low doses nocturnally administered
amitriptyline were compared to placebo in a double-blind crossover randomized study on
driving ability and driving-related skills involving seven chronic neuropathic pain
patients. Performance testing occurred at the first and last day of each 15-day drug
administration period, which was preceded by a 6-day washout phase. A standardized
method of measuring driving ability, the on-the-road driving test, was performed on all
visits. Patients were instructed to drive with a steady lateral position while
maintaining a constant speed of 95 km/h. The primary outcome of the driving test is the
Standard Deviation of Lateral Position (SDLP, cm), which is an index of weaving of the
car. At the first treatment day, driving performance was significantly impaired in
patients after nocturnal administration of 25 mg amitriptyline compared to placebo. The
increase in SDLP of 3 cm was higher than the increment generally observed with a blood
alcohol concentration of 0.5 mg/ml or higher, the legal limit for driving in many
countries. Also, reaction times on a memory test were significantly increased,
indicating worse performance after acute treatment of amitriptyline compared to placebo.
In contrast, after 2 weeks of treatment, no significant differences were found between
amitriptyline and placebo, suggesting that tolerance had developed to the impairing
effects of amitriptyline.
Key Words:
amitriptyline, driving, SDLP, neuropathic pain, psychomotor performance, cognition
