Khambam Sunil Kumar Reddy, Naidu Mur, Rani P Usha, Rao T Ramesh Kumar
Department of Clinical Pharmacology and Therapeutics, ICMR Advance Centre for Clinical Pharmacodynamic, Nizam's Institute of Medical Sciences, Hyderabad, Andhra Pradesh, India.
J Anaesthesiol Clin Pharmacol. 2012 Apr;28(2):214-20. doi: 10.4103/0970-9185.94887.
Assessment of the analgesic effect of an agent in an experimental pain model permits a level of control not possible in a clinical pain setting and is an ideal approach for evaluation of analgesic drugs. The aim of the present study was to establish a simple and reliable method of producing experimental pain, which can be used for screening of various analgesic agents.
The standardized method was followed in all cases, by recording thermal pain threshold in seconds in 24 healthy volunteers using hot air source at two different speeds, which is equipped in an acrylic-made chamber adjustable to three different levels. Reproducibility of the test procedure was evaluated by recording the thermal threshold parameter by a single observer on two sessions (interday reproducibility) and second observer on one session (interobserver reproducibility) separately. Validity of model was further tested by evaluating the analgesic effect of tramadol on 12 healthy volunteers.
Thermal pain model was found to produce low variability with coefficient of variation (CV) less than 10%. Interobserver and interday reproducibility were very good, as shown by Bland-Altman plot, with most of the values within ± 2SD. There was a significant increase in pain threshold time with use of tramadol as compared to placebo which was statistically significant (P < 0.05).
The newly developed pain model offers a stable and sensitive method for the early assessment of analgesic activity.
在实验性疼痛模型中评估一种药物的镇痛效果，可以实现临床疼痛环境中无法达到的控制水平，是评估镇痛药的理想方法。本研究的目的是建立一种简单可靠的产生实验性疼痛的方法，可用于筛选各种镇痛药。
所有病例均遵循标准化方法，使用配备在可调节至三种不同水平的丙烯酸制舱室内的热空气源，记录24名健康志愿者以两种不同速度的热痛阈值（以秒为单位）。通过由一名观察者在两个时间段记录热阈值参数（日间重复性）以及由第二名观察者在一个时间段记录热阈值参数（观察者间重复性）来分别评估测试程序的可重复性。通过评估曲马多对12名健康志愿者的镇痛效果，进一步测试模型的有效性。
发现热痛模型产生的变异性较低，变异系数（CV）小于10%。如Bland-Altman图所示，观察者间和日间重复性非常好，大多数值在±2SD范围内。与安慰剂相比，使用曲马多后疼痛阈值时间显著增加，具有统计学意义（P<0.05）。
新开发的疼痛模型为早期评估镇痛活性提供了一种稳定且敏感的方法。
