McMaster University

Michael G. DeGroote
National Pain Centre

Scope of Search

Canadian Guideline for Safe and Effective Use of Opioids for Chronic Non-Cancer Pain

Cluster 2: Conducting an Opioid Trial

R07. Recommendation Statement

No. Recommendation Keyword
R07 During dosage titration in a trial of opioid therapy, advise the patient to avoid driving a motor vehicle until a stable dosage is established and it is certain the opioid does not cause sedation (Grade C); and when taking opioids with alcohol, benzodiazepines, or other sedating drugs (Grade B). Titration and driving
  • R07. Discussion
  • R07. Summary of Peer-Reviewed Evidence

R07. Discussion

During an opioid trial titration, patients should be advised that opioids could cause cognitive effects that could impair their ability to drive. This caution is even more important in patients taking alcohol, benzodiazepines, or other sedating drugs with their opioids. For more details about opioids and driving, see Recommendation 14.

A "pharmacologically stable dose" is one that produces a fairly steady plasma level; it is established when the total daily dose is fixed for at least two weeks and:

1) frequency is scheduled and spread throughout the day


2) at least 70% of the prescribed opioid is controlled release.

R07. Summary of Peer-Reviewed Evidence

1. Patients who undergo a significant increase in the dose of narcotic experience significant cognitive impairment.

Bruera et al. reported on 40 patients with cancer pain: 20 had no change in narcotic dose (stable dose) and 20 had undergone an increase of more than 30% in dose (increased dose group). Cognitive changes were observed only in the increased dose group (Bruera 1989).

2. In a population receiving both narcotics and benzodiazepines, the cognitive impairment noted was found to be more likely due to benzodiazepines than to narcotics.

Hendler et al. compared three groups of patients: benzodiazepines alone, narcotics alone, and both benzodiazepine and narcotics. They found that narcotics did not impair cognitive functioning, memory or performance on visual and motor-perceptual tasks, however, cognitive impairment was much more apparent in patients receiving benzodiazepines (Hendler 1980).