Objectives: To address the need for faster pain relief of over-the-counter (OTC) analgesic users, a novel drug delivery technology was developed to achieve faster absorption of orally administered acetaminophen with the goal of delivering earlier onset of pain relief. Previous development studies suggested that a 1000 mg dose of this fast-acting acetaminophen (FA-acetaminophen) formulation provided faster absorption and onset of action versus, commercially available OTC fast-acting analgesics, 1000 mg of extra-strength acetaminophen (ES-acetaminophen) or 400 mg of liquid-filled ibuprofen capsules (LG-ibuprofen). This study was designed as the definitive trial evaluating the onset of pain relief of FA-acetaminophen versus these same OTC comparators.
Methods: This single-dose, randomized, double-blind, placebo- and active-controlled clinical trial compared analgesic onset, overall efficacy, and safety of FA-acetaminophen 1000 mg, ES-acetaminophen 1000 mg, LG-ibuprofen 400 mg, and placebo over 4 h in a postsurgical dental pain model. Following removal of 3 to 4 impacted third molars, 664 subjects with moderate-to-severe pain were randomized in a 4:4:2:1 ratio to FA-acetaminophen (249), ES-acetaminophen (232), LG-ibuprofen (124), or placebo (59). Mean age was 18.9 years; 45.5% were male; 57.5% had severe baseline pain intensity. Subjects stopped a first stopwatch if/when they had perceptible pain relief and a second stopwatch if/when their pain relief became meaningful to them. Pain intensity difference (PID) and pain relief (PAR) were obtained using an 11-point numerical rating scale.
Findings: FA-acetaminophen 1000 mg had faster median time to onset of pain relief (15.7 min) compared to ES-acetaminophen 1000 mg (20.2 min, p = 0.035), LG-ibuprofen 400 mg (23.2 min, p < 0.001), and placebo (non-estimable), statistically greater mean PAR and PID scores than other treatment groups at 15 and 30 min, and a statistically greater percentage of subjects with confirmed perceptible pain relief at 15 and 20 min. At 25 min, FA-acetaminophen 1000 mg had a statistically significantly greater percentage of subjects with confirmed perceptible pain relief than LG-ibuprofen 400 mg and placebo. No clinically significant adverse events were reported.
Conclusions: This study supports previous studies, demonstrating faster onset of analgesia with FA-acetaminophen 1000 mg compared to OTC ES-acetaminophen 1000 mg and OTC LG-ibuprofen 400 mg.
Clinicaltrials.gov identifier: NCT03224403 https://clinicaltrials.gov/ct2/show/NCT03224403.
Keywords: Acetaminophen; analgesic onset; fast-acting formulation; pain relief.