Combining paracetamol with a selective cyclooxygenase-2 inhibitor for acute pain relief after third molar surgery: a randomized, double-blind, placebo-controlled study

Efficacy of Tenoxicam, Paracetamol, and Their Combination in Postoperative Pain After Double-Jaw Surgery

Introduction Orthognathic surgical procedures include a series of surgical operations in which interventions are applied to the maxilla, mandible, or both for occlusal or aesthetic concerns due to facial skeletal development deformities. Double-jaw surgeries have the highest pain scores, in which both maxilla and mandible bones are intervened. This study aimed to compare the efficacy of individual applications of paracetamol and tenoxicam with their combined application on postoperative pain and opioid consumption in patients undergoing double-jaw surgery. Methods In this randomized, double-blind study, 60 patients undergoing double-jaw surgery were allocated into three groups, with each having 20 patients: the paracetamol group, the tenoxicam group, and the paracetamol-tenoxicam combination group. Pain intensity was evaluated using the visual analogue scale (VAS) at intervals of 30 minutes, 60 minutes, 120 minutes, and again at the 24th postoperative hour. Additionally, the consumption of opioids and other rescue analgesics was documented over the 24-hour postoperative period. Results The VAS values at 30 minutes, 60 minutes, and 24 hours were lower in the paracetamol-tenoxicam group compared to the other groups (p<0.001). The need for a rescue analgesic drug in the first 24 hours was not observed in the tenoxicam and paracetamol-tenoxicam groups. Conclusion It was concluded that both tenoxicam and paracetamol-tenoxicam combinations, especially the tenoxicam-paracetamol combination, were good options for postoperative analgesia in patients with double-jaw surgery.

Paracetamol (acetaminophen): A familiar drug with an unexplained mechanism of action

Paracetamol (acetaminophen) is undoubtedly one of the most widely used drugs worldwide. As an over-the-counter medication, paracetamol is the standard and first-line treatment for fever and acute pain and is believed to remain so for many years to come. Despite being in clinical use for over a century, the precise mechanism of action of this familiar drug remains a mystery. The oldest and most prevailing theory on the mechanism of analgesic and antipyretic actions of paracetamol relates to the inhibition of CNS cyclooxygenase (COX) enzyme activities, with conflicting views on the COX isoenzyme/variant targeted by paracetamol and on the nature of the molecular interactions with these enzymes. Paracetamol has been proposed to selectively inhibit COX-2 by working as a reducing agent, despite the fact that in vitro screens demonstrate low potency on the inhibition of COX-1 and COX-2. In vivo data from COX-1 transgenic mice suggest that paracetamol works through inhibition of a COX-1 variant enzyme to mediate its analgesic and particularly thermoregulatory actions (antipyresis and hypothermia). A separate line of research provides evidence on potentiation of the descending inhibitory serotonergic pathway to mediate the analgesic action of paracetamol, but with no evidence of binding to serotonergic molecules. AM404 as a metabolite for paracetamol has been proposed to activate the endocannabinoid and the transient receptor potential vanilloid-1 (TRPV1) systems. The current review gives an update and in some cases challenges the different theories on the pharmacology of paracetamol and raises questions on some of the inadequately explored actions of paracetamol. List of Abbreviations: AM404, N-(4-hydroxyphenyl)-arachidonamide; CB1R, Cannabinoid receptor-1; Cmax, Maximum concentration; CNS, Central nervous system; COX, Cyclooxygenase; CSF, Cerebrospinal fluid; ED50, 50% of maximal effective dose; FAAH, Fatty acid amidohydrolase; IC50, 50% of the maximal inhibitor concentration; LPS, Lipopolysaccharide; NSAIDs, Non-steroidal anti-inflammatory drugs; PGE2, Prostaglandin E2; TRPV1, Transient receptor potential vanilloid-1.

The Efficacy and Clinical Safety of Various Analgesic Combinations for Post-Operative Pain after Third Molar Surgery: A Systematic Review and Meta-Analysis

OBJECTIVES

To run a systematic review and meta-analysis of randomized clinical trials aiming to answer the clinical question "which analgesic combination and dosage is potentially the most effective and safe for acute post-operative pain control after third molar surgery?".

MATERIALS AND METHODS

A systematic search of computer databases and journals was performed. The search and the evaluations of articles were performed by 2 independent reviewers in 3 rounds. Randomized clinical trials related to analgesic combinations for acute post-operative pain control after lower third molar surgery that matched the selection criteria were evaluated to enter in the final review.

RESULTS

Fourteen studies with 3521 subjects, with 10 groups (17 dosages) of analgesic combinations were included in the final review. The analgesic efficacy were presented by the objective pain measurements including sum of pain intensity at 6 hours (SPID6) and total pain relief at 6 hours (TOTPAR6). The SPID6 scores and TOTPAR6 scores of the reported analgesic combinations were ranged from 1.46 to 6.44 and 3.24 - 10.3, respectively. Ibuprofen 400mg with oxycodone HCL 5mg had superior efficacy (SPID6: 6.44, TOTPAR6: 9.31). Nausea was the most common adverse effect, with prevalence ranging from 0-55%. Ibuprofen 200mg with caffeine 100mg or 200mg had a reasonable analgesic effect with fewer side effects.

CONCLUSION

This systematic review and meta-analysis may help clinicians in their choices of prescribing an analgesic combination for acute post-operative pain control after lower third molar surgery. It was found in this systematic review Ibuprofen 400mg combined with oxycodone HCL 5mg has superior analgesic efficacy when compared to the other analgesic combinations included in this study.

Assay sensitivity of pain intensity versus pain relief in acute pain clinical trials: ACTTION systematic review and meta-analysis

The magnitude of the effect size of an analgesic intervention can be influenced by several factors, including research design. A key design component is the choice of the primary endpoint. The purpose of this meta-analysis was to compare the assay sensitivity of 2 efficacy paradigms: pain intensity (calculated using summed pain intensity difference [SPID]) and pain relief (calculated using total pain relief [TOTPAR]). A systematic review of the literature was performed to identify acute pain studies that calculated both SPIDs and TOTPARs within the same study. Studies were included in this review if they were randomized, double-blind, placebo-controlled investigations involving medications for postsurgical acute pain and if enough data were provided to calculate TOTPAR and SPID standardized effect sizes. Based on a meta-analysis of 45 studies, the mean standardized effect size for TOTPAR (1.13) was .11 higher than that for SPID (1.02; P = .01). Mixed-effects meta-regression analyses found no significant associations between the TOTPAR - SPID difference in standardized effect size and trial design characteristics. Results from this review suggest that for acute pain studies, utilizing TOTPAR to assess pain relief may be more sensitive to treatment effects than utilizing SPID to assess pain intensity.

PERSPECTIVE

The results of this meta-analysis suggest that TOTPAR may be more sensitive to treatment effects than SPIDs are in analgesic trials examining acute pain. We found that standardized effect sizes were higher for TOTPAR compared to SPIDs.

Combining paracetamol (acetaminophen) with nonsteroidal antiinflammatory drugs: a qualitative systematic review of analgesic efficacy for acute postoperative pain

BACKGROUND

There has been a trend over recent years for combining a nonsteroidal antiinflammatory drug (NSAID) with paracetamol (acetaminophen) for pain management. However, therapeutic superiority of the combination of paracetamol and an NSAID over either drug alone remains controversial. We evaluated the efficacy of the combination of paracetamol and an NSAID versus either drug alone in various acute pain models.

METHODS

A systematic literature search of Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, and PubMed covering the period from January 1988 to June 2009 was performed to identify randomized controlled trials in humans that specifically compared combinations of paracetamol with various NSAIDs versus at least 1 of these constituent drugs. Identified studies were stratified into 2 groups: paracetamol/NSAID combinations versus paracetamol or NSAIDs. We analyzed pain intensity scores and supplemental analgesic requirements as primary outcome measures. In addition, each study was graded for quality using a validated scale.

RESULTS

Twenty-one human studies enrolling 1909 patients were analyzed. The NSAIDs used were ibuprofen (n = 6), diclofenac (n = 8), ketoprofen (n = 3), ketorolac (n = 1), aspirin (n = 1), tenoxicam (n = 1), and rofecoxib (n = 1). The combination of paracetamol and NSAID was more effective than paracetamol or NSAID alone in 85% and 64% of relevant studies, respectively. The pain intensity and analgesic supplementation was 35.0% +/- 10.9% and 38.8% +/- 13.1% lesser, respectively, in the positive studies for the combination versus paracetamol group, and 37.7% +/- 26.6% and 31.3% +/- 13.4% lesser, respectively, in the positive studies for the combination versus the NSAID group. No statistical difference in median quality scores was found between experimental groups.

CONCLUSION

Current evidence suggests that a combination of paracetamol and an NSAID may offer superior analgesia compared with either drug alone.

Single dose oral rofecoxib for acute postoperative pain in adults

BACKGROUND

Editor's note: The anti-inflammatory drug rofecoxib (Vioxx) was withdrawn from the market at the end of September 2004 after it was shown that long-term use (greater than 18 months) could increase the risk of heart attack and stroke in a study of secondary prevention of adenoma recurrence. Further information is available at www.vioxx.com.Rofecoxib is a selective cyclooxygenase-2 (COX-2) inhibitor previously licensed for treating acute and chronic pain; it was associated with fewer gastrointestinal adverse events than conventional NSAIDs. An earlier Cochrane review (Barden 2005) showed that rofecoxib is at least as effective as conventional non-steroidal anti-inflammatory drugs (NSAIDs) for postoperative pain.

OBJECTIVES

To assess the analgesic efficacy and adverse effects of rofecoxib in single oral doses for moderate and severe postoperative pain.

SEARCH STRATEGY

We searched Cochrane CENTRAL, MEDLINE, EMBASE and the Oxford Pain Relief Database for studies to June 2009.

SELECTION CRITERIA

Randomised, double blind, placebo-controlled trials of single dose orally administered rofecoxib in adults with moderate to severe acute postoperative pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. Pain relief or pain intensity data were extracted and converted into the dichotomous outcome of number of participants with at least 50% pain relief over 4 to 6 hours, from which relative risk and number needed to treat to benefit (NNT) were calculated. Numbers of participants using rescue medication over specified time periods, and time to use of rescue medication, were sought as additional measures of efficacy. Information on adverse events and withdrawals was collected.

MAIN RESULTS

Twenty new studies and seven from the earlier review met the inclusion criteria. Twenty-four studies were in dental surgery and three in other types of surgery. In total, 2636 participants were treated with rofecoxib 50 mg, 20 with rofecoxib 500 mg, and 1251 with placebo. The NNT for at least 50% pain relief over 4 to 6 hours with rofecoxib 50 mg was 2.2 (2.0 to 2.3) in all studies combined, 1.9 (1.8 to 2.0) in dental studies, and 6.8 (4.6 to 13) in other types of surgery. The median time to use of rescue medication was 14 hours for rofecoxib 50 mg and 2 hours for placebo. Significantly fewer participants used rescue medication following rofecoxib 50 mg than with placebo. Adverse events did not differ from placebo.

AUTHORS' CONCLUSIONS

Rofecoxib 50 mg (two to four times the standard daily dose for chronic pain) is an effective single dose oral analgesic for acute postoperative pain in adults, with a relatively long duration of action.

Single dose oral paracetamol (acetaminophen) for postoperative pain in adults

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 1, 2004 - this original review had been split from a previous title on 'Single dose paracetamol (acetaminophen) with and without codeine for postoperative pain'. The last version of this review concluded that paracetamol is an effective analgesic for postoperative pain, but additional trials have since been published. This review sought to evaluate the efficacy and safety of paracetamol using current data, and to compare the findings with other analgesics evaluated in the same way.

OBJECTIVES

To assess the efficacy of single dose oral paracetamol for the treatment of acute postoperative pain.

SEARCH STRATEGY

We searched The Cochrane Library, MEDLINE, EMBASE, the Oxford Pain Relief Database and reference lists of articles to update an existing version of the review in July 2008.

SELECTION CRITERIA

Randomised, double-blind, placebo-controlled clinical trials of paracetamol for acute postoperative pain in adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. Area under the "pain relief versus time" curve was used to derive the proportion of participants with paracetamol or placebo experiencing at least 50% pain relief over four to six hours, using validated equations. Number-needed-to-treat-to-benefit (NNT) was calculated, with 95% confidence intervals (CI). The proportion of participants using rescue analgesia over a specified time period, and time to use, were sought as measures of duration of analgesia. Information on adverse events and withdrawals was also collected.

MAIN RESULTS

Fifty-one studies, with 5762 participants, were included: 3277 participants were treated with a single oral dose of paracetamol and 2425 with placebo. About half of participants treated with paracetamol at standard doses achieved at least 50% pain relief over four to six hours, compared with about 20% treated with placebo. NNTs for at least 50% pain relief over four to six hours following a single dose of paracetamol were as follows: 500 mg NNT 3.5 (2.7 to 4.8); 600 to 650 mg NNT 4.6 (3.9 to 5.5); 975 to 1000 mg NNT 3.6 (3.4 to 4.0). There was no dose response. Sensitivity analysis showed no significant effect of trial size or quality on this outcome.About half of participants needed additional analgesia over four to six hours, compared with about 70% with placebo. Five people would need to be treated with 1000 mg paracetamol, the most commonly used dose, to prevent one needing rescue medication over four to six hours, who would have needed it with placebo. Adverse event reporting was inconsistent and often incomplete. Reported adverse events were mainly mild and transient, and occurred at similar rates with 1000 mg paracetamol and placebo. No serious adverse events were reported. Withdrawals due to adverse events were uncommon and occurred in both paracetamol and placebo treatment arms.

AUTHORS' CONCLUSIONS

A single dose of paracetamol provides effective analgesia for about half of patients with acute postoperative pain, for a period of about four hours, and is associated with few, mainly mild, adverse events.