[Interactions between benzodiazepines and opioids].

Benzodiazepines and opiates or opioids are used concomitantly in various circumstances, for example in anesthesiology, for the management of acute or chronic pain and for substitution therapy in heroin addiction. There are numerous interactions between these two families of substances. The objective of this review is to present the interactions identified in clinical and experimental studies reported in the literature dealing with their effects on pain, anxiety, sedation and respiration. The exact mechanism of benzodiazepine and opioid interactions remains to be established. It may depend on pharmacokinetic or pharmacodynamic mechanisms. Certain arguments would support the pharmacodynamic hypothesis: the co-location of GABA and opiate receptors in the central nervous system, the existence of possible cross-reactivity and common pathways of intracellular transduction. The deleterious interaction of benzodiazepines and opioids on respiration may take place at the level of the central command of ventilation or may be related to additive actions on the different neuromuscular components of the respiration. A better understanding of the exact mechanisms implicated in these interactions would increase the safety of prescription of these drugs.