Measurement of Pathological Pain in Distinction to Experimental Pain

Abstract

The real analgesic power of a drug must be determined by its capacity to relieve naturally occurring pain. This is so because the pain of man consists of both the perception of painful stimuli and the psychic modification of these stimuli. A method of measuring postoperative pain in terms of its relief by narcotics and of measuring analgesic power in terms of frequency of relief of postoperative pain has been described by Denton and Beecher. Improvements in the method are described here. The drug,the potency of which is to be determined,is alternated with a standard dose of morphine sulfate (10 mg./70 kg. body wt. subcut.) in individual patients in treatment of the their pain. The frequency of pain relief in each group of patients with each drug is recorded and the dose of the unknown altered appropriately until equivalent analgesia is obtained. All drugs are treated as unknowns to the patients and observers. When morphine itself was used as the unknown, 10.8 mg. was found to be equianalgesic to the standard. Data are presented to show that the amt. of postoperative pain in individual patients is unrelated within wide limits to any known characteristic of the individual or surgical procedure. The variation in response of man to a standard dose of morphine is also quantitated.