BACKGROUND: Although reproducibility is considered essential for any method used in scientific research, it is investigated only rarely; thus, strikingly little has been published regarding the... Show moreBACKGROUND: Although reproducibility is considered essential for any method used in scientific research, it is investigated only rarely; thus, strikingly little has been published regarding the reproducibility of evoked pain models involving human subjects. Here, we studied the reproducibility of a battery of evoked pain models for demonstrating the analgesic effects of two analgesic compounds. METHODS: A total of 81 healthy subjects participated in four studies involving a battery of evoked pain tests in which mechanical, thermal and electrical stimuli were used to measure pain detection and tolerance thresholds. Pharmacodynamic outcome variables were analysed using a mixed model analysis of variance, and a coefficient of variation was calculated by dividing the standard deviation by the least squares means. RESULTS: A total of 76 subjects completed the studies. After being administered pregabalin, the subjects' pain tolerance thresholds in the cold pressor and pressure stimulation tests were significantly increased compared to the placebo group. Moreover, the heat pain detection threshold in Show less
AIMInhibitors of nerve growth factor (NGF) reduce pain in several chronic pain indications. NGF signals through tyrosine kinase receptors of the tropomyosin-related kinase (Trk) family and the... Show moreAIMInhibitors of nerve growth factor (NGF) reduce pain in several chronic pain indications. NGF signals through tyrosine kinase receptors of the tropomyosin-related kinase (Trk) family and the unrelated p75 receptor. PF-06273340 is a small molecule inhibitor of Trks A, B and C that reduces pain in nonclinical models, and the present study aimed to investigate the pharmacodynamics of this first-in-class molecule in humans.METHODSA randomized, double-blind, single-dose, placebo- and active-controlled five-period crossover study was conducted in healthy human subjects (NCT02260947). Subjects received five treatments: PF-06273340 50mg, PF-06273340 400 mg, pregabalin 300 mg, ibuprofen 600 mg and placebo. The five primary endpoints were the pain detection threshold for the thermal pain tests and the pain tolerance threshold for the cold pressor, electrical stair and pressure pain tests. The trial had predefined decision rules based on 95% confidence that the PF-06273340 effect was better than that of placebo.RESULTSTwenty subjects entered the study, with 18 completing all five periods. The high dose of PF-06273340 met the decision rules on the ultraviolet (UV) B skin thermal pain endpoint [least squares (LS) mean vs. placebo: 1.13, 95% confidence interval: 0.64–1.61], but not on the other four primary endpoints. The low dose did not meet the decision criteria for any of the five primary endpoints. Pregabalin (cold pressor and electrical stair tests) and ibuprofen (UVB thermal pain) showed significant analgesic effects on expected endpoints.CONCLUSIONSThe study demonstrated, for the first time, the translation of nonclinical effects into man in an inflammatory pain analgesic pharmacodynamic endpoint using a pan-Trk inhibitor. Show less
