Send to

Choose Destination
Br J Clin Pharmacol. 2009 Aug;68(2):149-68. doi: 10.1111/j.1365-2125.2009.03456.x.

Assessing analgesic actions of opioids by experimental pain models in healthy volunteers - an updated review.

Author information

Center for Sensory-Motor Interactions, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7, Aalborg 9000, Denmark.



Experimental pain models may help to evaluate the mechanisms of action of analgesics and target the clinical indications for their use. This review addresses how the efficacy of opioids can be assessed in human volunteers using experimental pain models. The drawback with the different study designs is also discussed.


A literature search was completed for randomized controlled studies which included human experimental pain models, healthy volunteers and opioids.


Opioids with a strong affinity for the micro-opioid receptor decreased the sensation in a variety of experimental pain modalities, but strong tonic pain was attenuated more than short lasting pain and non-painful sensations. The effects of opioids with weaker affinity for the micro-opioid receptor were detected by a more narrow range of pain models, and the assessment methods needed to be more sensitive.


The way the pain is induced, assessed and summarized is very important for the sensitivity of the pain models. This review gives an overview of how different opioids perform in experimental pain models. Generally experimental pain models need to be designed with careful consideration of pharmacological mechanisms and pharmacokinetics of analgesics. This knowledge can aid the decisions needed to be taken when designing experimental pain studies for compounds entering phase 1 clinical trials.

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center