Augmentation of acetaminophen analgesia by the antihistamine phenyltoloxamine

A double-blind, placebo-controlled, parallel-group study was performed to compare the analgesic activity of the combination of 650 mg acetaminophen plus 60 mg phenyltoloxamine citrate with that of 650 mg acetaminophen alone. Two hundred female inpatients who had severe pain associated with a recent episiotomy procedure were randomly assigned to receive a single dose of one of the two active treatments or a placebo. Analgesia was assessed over a 6-hour period. Treatments were compared on the basis of standard subjective scales for pain intensity and relief, a number of derived variables based on these data and two global measures. For essentially all measures, the two active treatments were significantly superior to the placebo control. The combination was significantly superior to acetaminophen alone for all analgesic measures including SPID, TOTAL, and global ratings. The results of this study demonstrate that 60 mg phenyltoloxamine produces significant augmentation of the analgesic activity of 650 mg acetaminophen in postepisiotomy pain.