title: Development of a simple radiant heat induced experimental pain model for evaluation of analgesics in normal healthy human volunteers.
abstract: OBJECTIVE
  Human experimental pain models help to understand the mechanism of the painful conditions and can also be adopted to test analgesic efficacy of drugs. In early phases, the clinical development of new analgesics is hindered due to the lack of reliable tests for the experimental pain models. In the present study, we have developed and validated a simple radiant heat pain model which can be used for future screening of various analgesic agents.
  
  
  METHODS
  We have standardized the thermal pain model by recording pain threshold and pain tolerance time in seconds at three different intensities and levels in 24 healthy subjects. Reproducibility of the test procedure was evaluated by recording the pain parameters by two observers on three consecutive days. Validity of model was further tested by evaluating the analgesic effect of tramadol.
  
  
  CONCLUSIONS
  Use of radiant heat pain model with high intensity and short level was found to produce low variability with coefficient of variation less than 5%. Interobserver and interperiod reproducibility was very good as shown by Bland - Altman plot; with most of the values within ± 2SD. Tramadol produced statistically significant increase in pain threshold time. The newly developed pain model produces a type of experimental pain which is responsive to analgesic effects of tramadol at clinically relevant doses.
authors.affiliation: ICMR Advance Centre for Clinical Pharmacodynamic, Department of Clinical Pharmacology and Therapeutics, Nizam's Institute of Medical Sciences, Hyderabad - 500 082, India.
authors.forename: M U R
authors.initials: MU
authors.lastname: Naidu
authors.forename: K Sunil Kumar
authors.initials: KS
authors.lastname: Reddy
authors.forename: P Usha
authors.initials: PU
authors.lastname: Rani
authors.forename: T Ramesh Kumar
authors.initials: TR
authors.lastname: Rao