The combination of 500 mg acetaminophen and 150 mg ibuprofen has been shown to improve analgesia compared with the individual components, when given as 2 tablets (i.e., total of 1,000/300 mg) 4 times a day for dental pain.
The analgesic relief from 2 tablets of the combination was around 6 hours, and so consistent with 4 times a day dosing.
The combination tablets are scored to allow for lower doses and can be given as 2 tablets (total of 1,000/300 mg), 1 tablet (500/150 mg) or ½ tablet (250/75 mg) in multiple doses.
However different dose response combinations need to be investigated to confirm the dose response curve of the combination and to compare the relative efficacy with acetaminophen and different doses of ibuprofen (lower and higher dose).
The study hypothesis is the analgesic response to three different combination doses, the three single component doses 500mg acetaminophen and 150mg and 300mg ibuprofen, and placebo administered four times daily over 24 hours for post-operative dental pain will form a representative dose response curve.
The study design is multi-centre, prospective, placebo-controlled, randomized, double-blind, factorial parallel group.
Participants will be stratified for baseline pain at inclusion (moderate or severe pain based a 4 point pain intensity rating scale).
Recruitment will continue until there are at least 350 participants in the ITT population.
Efficacy: The primary efficacy objective is to compare the time-adjusted SPIDs (Summed Pain Intensity Differences) of the VAS pain intensity scores up to 24 hours after the first dose of study medication among the 7 treatment groups to determine the form of the dose-response relationship.
Secondary efficacy objectives are:
* To compare the maximum VAS pain scores for the 24-hour period after the first dose of study medication among the seven treatment groups to determine the form of the dose response relationship.
* To compare the response rates (response rate to be defined as the percentage of participants who achieve at least 50% reduction in baseline pain within 6 hours i.e. the first dose period) among the seven treatment groups to determine the form of the dose response relationship.
* To determine and compare the time to peak reduction in VAS pain intensity scores following the first dose of study medication among the seven treatment groups to determine the form of the dose response relationship.
* To compare time to perceptible and meaningful pain relief among the seven treatment groups using the two stopwatch method.
* To compare the time to requirement for rescue medication among the seven treatment groups.
* To compare the amount of rescue medication used (defined as the number of tablets) among the seven treatment groups over the 24-hour treatment period.
* To compare the percentage of participants requiring rescue medication among the seven treatment groups.
* To compare the categorical global pain rating among the seven treatment groups.
Safety:
To compare adverse event rates (divided into serious and non-serious adverse events). Adverse events will be assessed for the 24- hour study period and up to 30 days after the final dose of study medication among the seven treatment groups.
The standard symptoms expected in subjects who have recently undergone third molar extraction will not be recorded as AEs in this study, unless they are of greater severity and/or intensity than would be expected. The events considered to be standard for the purposes of this study are:
* Oral pain.
* Facial swelling.
* Oral bleeding.
* Bruising to face, neck, and/or jaw.
* Decreased range of motion of the jaw.
* Dry socket.
The Investigators will use their clinical judgement in determining whether these symptoms are of greater severity and/or intensity than would be expected.
Planned hospital admissions and/or surgical operations for an illness or disease which existed before the drug was given or the participant was randomized in a clinical study will not be considered adverse events The incidence of known specific NSAID and acetaminophen side effects (e.g. GI ulceration, Indigestion/stomach pain, post-operative bleeding, thromboembolic events and evidence of clinical hepatitis) during the 24-hour study period and up to 30 days after the last dose will be compared among the seven treatments.
