Benzodiazepines are most commonly prescribed for the management of anxiety and insomnia. They can also be used for sedation or amnesia before medical or surgical procedures, treatment of seizure, treatment of alcohol or sedative withdrawal, or acute agitation. Known side effects include drowsiness, fatigue and ataxia (the loss of full control of bodily movements).
Opioids are used most commonly for treatment of pain. Like benzodiazepines, they also have the potential to cause depression, resulting in sedation and decreased mental alertness.
This Rapid Response Report from the Canadian Agency for Drugs and Technologies in Health (CADTH) examined the evidence on the risk of serious adverse events related to combination benzodiazepine-opioid use.
The report was limited in scope, but it did find some evidence from non-randomised studies that suggests a positive association with the use of benzodiazepines in combination with methadone and mortality risk.
The reviewers concluded:
According to the evidence, there is a positive association between the risk of death and the use of benzodiazepines in combination with methadone. Though limited, there is an indication that opioids, including buprenorphine, have the potential for increased risk in combination with benzodiazepines. Clinical mechanisms are hypothesised.
As a result, it seems reasonable that use of opioids with benzodiazepines should be limited until this risk is further clarified, with each patient case assessed on its own merits. Further research that will examine the effect of combination benzodiazepines use and opioid therapy, especially buprenorphine, may demonstrate lower risk with this combination.
Combination Benzodiazepine-Opioid Use: A Review of the Evidence on Safety (PDF). Canadian Agency for Drugs and Technologies in Health (CADTH), 16 Sep 2011.