Expert review of neurotherapeutics
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Expert Rev Neurother · Nov 2011
ReviewOptimizing the early phase development of new analgesics by human pain biomarkers.
Human pain biomarkers are based on standardized acute activation of pain pathways/mechanisms and quantitative assessment of the evoked responses. This approach can be applied to healthy volunteers, to pain patients, and before and after pharmacological interventions to help understanding and profile the mode of action (proof-of-concept) of new and existing analgesic compounds. Standardized stimuli of different modalities can be applied to different tissues (multimodal and multi-tissue) for profiling analgesic compounds with respect to modulation of pain transduction, transmission, specific mechanisms and processing. ⋯ Human pain biomarkers can be translational and may bridge animal findings in clinical pain conditions, which in turn can provide new possibilities for designing more successful clinical trials. Biomarker based proof-of-concept drug studies in either volunteers or selected patient populations provide inexpensive, fast and reliable mechanism-based information about dose-efficacy relationships. This is important information in the early drug development phase and for designing large expensive clinical trials.
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Trigeminal neuralgia (TN) and persistent idiopathic facial pain (PIFP) are two of the most puzzling orofacial pain conditions and affected patients are often very difficult to treat. TN is characterized by paroxysms of brief but severe pain followed by asymptomatic periods without pain. In some patients a constant dull background pain may persist. ⋯ Epidemiologic evidence on TN, and even more so on PIFP, is quite scarce, but generally both conditions are considered to be rare diseases. The etiology and underlying pathophysiology of TN, and more so PIFP, remain unknown. Treatment is based on only few randomized controlled clinical trials and insufficiently evaluated surgical procedures.