Analgesic efficacy of acetaminophen 1000 mg, acetaminophen 2000 mg, and the combination of acetaminophen 1000 mg and codeine phosphate 60 mg versus placebo in acute postoperative pain.

Acetaminophen (APAP) 1000 mg, APAP 2000 mg, the combination of APAP 1000 mg plus codeine phosphate 60 mg (APAPCOD), and placebo (PBO) were compared in a 6-hour, randomized, single-dose, double-blind, parallel-group analgesic trial. All active treatments were statistically superior (p less than 0.05) to placebo for 4 hours after medication with respect to pain intensity (PI) and pain intensity difference (PID), and up to 3 hours regarding pain relief (PAR). The combination scored better than all other treatments on the summary analgesic efficacy measures sum PI (SUMPI), sum PID (SPID), and total PAR (TOTPAR). The combination was statistically superior to APAP 1000 mg on SUMPI, TOTPAR and maximum PAR (MAXPAR). Acetaminophen 2000 mg showed marginal numerical superiority over 1000 mg for SUMPI, but was not statistically superior for any summary efficacy measure. The 2000-mg dose was numerically inferior to APAPCOD for every summary efficacy measure and statistically inferior regarding SPID and MAXPAR. We concluded that codeine 60 mg added to acetaminophen 1000 mg offers analgesic advantages, and acetaminophen reaches an analgesic ceiling effect at 1000 mg using the dental pain model.