Human models could be way forward for assessing analgesic efficacy

By Piriya Mahendra, medwireNews Reporter

Researchers say that human experimental pain models could be used to assess the clinical efficacy of analgesics in phase I clinical studies.

Bruno Oertel and Jörn Lötsch, both from Goethe University in Frankfurt-Am-Main, Germany, explained in a press statement that finding novel analgesics is difficult as pain cannot be measured directly in animal models and human trials.

In addition, they say, the human body has a number of ways of detecting painful stimuli and each mechanism responds to a different type of analgesic.

"We thought that if a pain-relieving drug was effective in a particular experimental pain model and also in a specific type of clinical pain, then the experimental model should be predictive for the particular clinical setting," commented Oertel and Lötsch.

In a review of the available literature, published in the British Journal of Pharmacology, they found that human experimental pain models were better able to predict the efficacy of an analgesic than previously thought. In fact, the overall prediction of analgesic efficacy or drug failure correlated well between experimental and clinical settings. "Not using these pain models in drug development seems to be unjustified - in fact they should be used routinely in drug development programmes," remarked Oertel.

However, Oertel and Lötsch point out that the correct selection of a model requires more detailed information about which model predicts which clinical pain condition. They hypothesized that if an analgesic drug was effective in an experimental pain model as well as a clinical setting, then the model might be predictive for a particular pain clinical setting and should be favored for testing analgesics targeted at that particular pain condition.

"We identified that different sets of experimental pain models, rather than single models, may be best suited to provide cost-effective yet predictive studies in analgesic drug development," explained Lötsch.

The authors acknowledge that further analysis must be conducted before the approach is ready to use, but they believe that it could be a more cost-effective way to aid scientists in obtaining information about how analgesics work.

Ian McGrath, Editor-in-Chief of the British Journal of Pharmacology said: "It is difficult and unusual to undertake truly translational research in pharmacology. Here, Jörn Lötsch and Bruno Oertel have focused on experiments on humans to bridge the gap between animal research and clinical pharmacology."

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