An evaluation of different doses of soluble aspirin and aspirin tablets in postoperative dental pain

Single dose oral aspirin for acute postoperative pain in adults

BACKGROUND

This review is an update of a previously published review in the Cochrane Database of Systematic Reviews on 'Single dose oral aspirin for acute pain'. Aspirin has been known for many years to be an effective analgesic for many different pain conditions. Although its use as an analgesic is now limited in developed countries, it is widely available, inexpensive, and remains commonly used throughout the world.

OBJECTIVES

To assess the analgesic efficacy and associated adverse events of single dose oral aspirin in acute postoperative pain.

SEARCH METHODS

For the earlier review, we identified randomised trials by searching CENTRAL (The Cochrane Library) (1998, Issue 1), MEDLINE (1966 to March 1998), EMBASE (1980 to January 1998), and the Oxford Pain Relief Database (1950 to 1994). We updated searches of CENTRAL, MEDLINE, and EMBASE to January 2012.

SELECTION CRITERIA

Single oral dose, randomised, double-blind, placebo-controlled trials of aspirin for relief of established moderate to severe postoperative pain in adults.

DATA COLLECTION AND ANALYSIS

We assessed studies for methodological quality and two review authors extracted the data independently. We used summed total pain relief (TOTPAR) over four to six hours to calculate the number of participants achieving at least 50% pain relief. We used these derived results to calculate, with 95% confidence intervals, the relative benefit compared to placebo, and the number needed to treat (NNT) for one participant to experience at least 50% pain relief over four to six hours. We sought numbers of participants using rescue medication over specified time periods, and time to use of rescue medication, as additional measures of efficacy. We collected information on adverse events and withdrawals.

MAIN RESULTS

We included 68 studies in which aspirin was used at doses from 300 mg to 1200 mg, but the vast majority of participants received either 600/650 mg (2409 participants, 64 studies) or 990/1000 mg (380 participants, eight studies). There was only one new study.Studies were overwhelmingly of adequate or good methodological quality. NNTs for at least 50% pain relief over four to six hours were 4.2 (3.9 to 4.8), 3.8 (3.0 to 5.1), and 2.7 (2.0 to 3.8) for 600/650 mg, 900/1000 mg, and 1200 mg respectively, compared with placebo. Type of pain model had no significant impact on the results. Lower doses were not significantly different from placebo. These results do not differ from those of the earlier review.Fewer participants required rescue medication with aspirin than with placebo over four to eight hours postdose, but by 12 hours there was no difference. The number of participants experiencing adverse events was not significantly different from placebo for 600/650 mg aspirin, but for 900/1000 mg the number needed to treat to harm was 7.5 (4.8 to 17). The most commonly reported events were dizziness, drowsiness, gastric irritation, nausea, and vomiting, nearly all of which were of mild to moderate severity.

AUTHORS' CONCLUSIONS

Aspirin is an effective analgesic for acute pain of moderate to severe intensity. High doses are more effective, but are associated with increased adverse events, including drowsiness and gastric irritation. The pain relief achieved with aspirin was very similar milligram for milligram to that seen with paracetamol. There was no change to the conclusions in this update.

Dose-response in direct comparisons of different doses of aspirin, ibuprofen and paracetamol (acetaminophen) in analgesic studies

AIMS

Establishing the dose-response relationship for clinically useful doses of aspirin, ibuprofen and paracetamol has been difficult. Indirect comparison from meta-analysis is compromised by too little information at some doses.

METHODS

A systematic review of randomized, double-blind trials in acute pain comparing different doses of aspirin, ibuprofen and paracetamol was therefore undertaken.

RESULTS

Fifty trials were found. Numerical superiority of higher over lower dose was found by the original authors in 37/50 trials (74%) and statistical superiority in 11/50 (22%). Twenty-eight trials had design, quality and data reporting characteristics to allow pooling of common doses; in 3/28 (11%) of the individual trials our calculations showed statistical superiority of higher over lower dose. Pooled comparison of 1000/1200 mg aspirin over 500/600 mg was statistically superior, with a number-needed-to-treat (NNT) for higher over lower dose of 16 (8 to > 100). Pooled comparison of 400 mg ibuprofen over 200 mg was statistically superior, with an NNT for higher over lower dose of 10 (6-23). Pooled comparison of 1000 mg paracetamol over 500 mg was statistically superior, with an NNT for higher over lower dose of 9 (6-20).

CONCLUSIONS

Use of trials making direct comparison of two different doses of target drugs revealed the underlying dose-response curve for clinical analgesia.

An investigation into the comparative efficacy of soluble aspirin and solid paracetamol in postoperative pain after third molar surgery

OBJECTIVE

To compare the efficacy of soluble aspirin 900 mg and paracetamol 1,000 mg in patients with postoperative pain after third molar surgery.

DESIGN

A randomised, placebo controlled, double-blind study.

SETTING

Day stay units of Oral and Maxillofacial Surgery at Cardiff Dental Hospital and Hexham General Hospital, Northumberland.

SUBJECTS AND METHODS

One hundred and sixty-seven (104 female) patients who required the removal of their impacted third molars under general anaesthesia.

INTERVENTION

In the early postoperative period, patients were medicated with either a single dose of soluble aspirin 900 mg, solid paracetamol 1,000 mg or placebo.

MAIN OUTCOME MEASURES

Pain intensity was measured on 100 mm visual analogue scales at 0, 5, 10, 15, 20, 30, 45, 60, 90, 120 and 240 minutes after dosing. Other efficacy variables evaluated included time to rescue medication and an overall assessment of the study medication efficacy by the patient on completion of the study.

RESULTS

One hundred and sixty-seven patients consented to take part in the study, but only 153 were medicated. Of the 14 patients not treated, 10 failed to develop sufficient pain to enter the study, two withdrew consent, one had an adverse reaction to the general anaesthetic and one was a protocol violator. Over the four hour investigation period, patients treated with soluble aspirin reported significantly less pain when compared with those treated with paracetamol (mean difference in AUC(0-240) = -2001, 95% CI -3893 to -109, p=0.038) and placebo (mean difference in AUC(0-240) = -3470, 95% CI -5719 to -1221, p=0.003). Similarly, at 20 and 30 minutes after dosing, patients in the soluble aspirin group were reporting significantly less pain than those in the paracetamol treatment group (mean difference in pain intensity: at 20 minutes -7.9, 95% CI -15.3 to -0.6, p=0.035; at 30 minutes -10.6, 95% CI -18.6 to -2.6, p=0.010). There were no significant differences between treatment groups with respect to the number of patients requiring rescue medication, however the time to dosing was significantly longer for those taking soluble aspirin when compared with placebo (hazard ratio 2.34, 95% CI 1.41 to 3.88, p<0.001).

CONCLUSION

The findings from this study showed that soluble aspirin 900 mg provides significant and more rapid analgesia than paracetamol 1,000 mg in the early postoperative period after third molar surgery.

Single dose oral aspirin for acute pain

BACKGROUND

Aspirin has been known to be an effective analgesic for many years and is commonly used throughout the world for many different pain conditions. It is important for both prescribers and patients to have the best possible information about the efficacy and safety of analgesics, and this need is reflected in patient surveys which show that postoperative pain is often poorly managed. We also need to benchmark relative efficacy and safety of current analgesics so that we can compare them with new analgesics.

OBJECTIVES

To quantitatively assess the analgesic efficacy and adverse effects of a single-dose of aspirin in acute pain of moderate to severe intensity.

SEARCH STRATEGY

Randomised trials were identified by searching Medline (1966 to March 1998), Embase (1980 to January 1998), the Cochrane Library (Issue 1,1998) and the Oxford Pain Relief Database (1950 to 1994).

SELECTION CRITERIA

The inclusion criteria used were: full journal publication, postoperative pain or a mixture of postoperative and acute trauma pain, oral administration, adult patients, baseline pain of moderate to severe intensity, double-blind design, and random allocation to treatment groups which compared aspirin with placebo.

DATA COLLECTION AND ANALYSIS

Summed pain relief or pain intensity difference over four to six hours was extracted, and converted into dichotomous information yielding the number of patients with at least 50% pain relief. This was then used to calculate the relative benefit and the number-needed-to-treat (NNT) for one patient to achieve at least 50% pain relief.

MAIN RESULTS

Seventy-two randomised single-dose trials met our inclusion criteria, with 3253 patients given aspirin, and 3297 placebo. Significant benefit of aspirin over placebo was shown for aspirin 600/650 mg, 1000 mg and 1200 mg, NNTs for at least 50% pain relief of 4.4 (4.0 to 4.9), 4.0 (3.2 to 5.4) and 2.4 (1.9 to 3.2) respectively. Single-dose aspirin 600/650 mg produced significantly more drowsiness and gastric irritation than placebo, with a number-needed-to-harm (NNH) of 28 (19 to 52) and 38 (22 to 174) respectively. Type of pain model, pain measurement, sample size, quality of study design, and study duration had no significant impact on the results.

REVIEWER'S CONCLUSIONS

Aspirin is an effective analgesic for acute pain of moderate to severe intensity with a clear dose-response. Drowsiness and gastric irritation were seen as significant adverse effects even though the studies were single-dose. The pain relief achieved with aspirin was very similar milligram for milligram to that seen with paracetamol.

Are the pharmacokinetics of ibuprofen important determinants for the drug's efficacy in postoperative pain after third molar surgery?

The aim of the present placebo-controlled, crossover study was to evaluate the efficacy and pharmacokinetics of ibuprofen after a single oral dose of soluble ibuprofen 400 mg in 18 patients with postoperative pain after bilateral third molar surgery. Throughout a 5-hour investigation period, patients reported significantly less pain (P < 0.001) after treatment with soluble ibuprofen than after placebo. Peak plasma concentrations of ibuprofen occurred approximately 30 minutes after dosage. No significant correlations (P > 0.05) were observed between efficacy measures and the various pharmacokinetic parameters (AUC0-300, Cmax and Tmax) for ibuprofen after the soluble dose. It is concluded that a single dose of soluble ibuprofen 400 mg is an effective analgesic for the control of postoperative pain in the early period after third molar surgery. Efficacy of this preparation does not appear to be directly related to the drug's pharmacokinetic variables in plasma.

The effect of tramadol on dento-alveolar surgical pain

The aim of the study was to assess the analgesic effect of tramadol in the relief of pain after dentoalveolar operations that involve the removal of bone and suturing. Four-hundred and fifty-two patients over the age of 18 years who were to undergo removal of impacted teeth (n = 362), removal of root (n = 79), or alveolectomy, enucleation of cysts, or removal of soft tissue (n = 11) under local anesthesia were studied. Patients were randomly allocated to receive tramadol 100 mg or 50 mg four times daily, or 50 mg twice daily, or placebo. Median pain scores on the day of operation in the three tramadol groups were similar (2 in each group, ranges 1-5, 1-4.8, and 1-5 respectively) and were all significantly lower than that in the placebo group (2.3 range 1-4.2). The median number of Paracetamol tablets taken by patients in the three tramadol groups was 2 (ranges 0-8, 0-12 and 0-8 respectively), and were all significantly less than in the placebo group (4, range 0-12). More patients given tramadol reported complete pain relief than the placebo group. The advantages of tramadol continued over the next 2 days. There were no serious or unexpected adverse effects. It is concluded that tramadol is an effective analgesic after dentoalveolar operations.

Comparative bioavailability of aspirin and paracetamol following single dose administration of soluble and plain tablets

In this study, the bioavailability of aspirin and paracetamol was compared in plain and soluble combination formulations in fasting, healthy volunteers. Blood samples were taken and Cmax, Tmax and AUC measured at various times following administration of single doses of the two formulations in 12 subjects. The rapidity of uptake of aspirin following administration of a soluble formulation suggests significant absorption from the stomach. There was no significant difference in the pharmacokinetic parameters of paracetamol derived from a soluble or plain formulation. A comparison of the uptake of aspirin from the soluble aspirin formulation with paracetamol from either plain or soluble tablets showed that aspirin entered the plasma and achieved peak levels significantly more quickly. However, the half life of paracetamol was significantly longer than that of aspirin. These findings suggest that onset of analgesia should be more rapid following dosing with soluble aspirin, a conclusion supported by comparative efficacy studies conducted with differing formulations of aspirin.

Effects of peripherally and centrally acting analgesics on somato-sensory evoked potentials

1. The effects of aspirin 1000 mg, paracetamol 1000 mg, codeine 60 mg on somatosensory evoked potentials (SEPs) were measured in a four-way cross-over study. 2. SEPs were elicited by electrical stimulation of the skin overlying the digital nerve at intensities close to pain threshold. 3. Amplitudes and latencies of both early and late SEPs were recorded, as well as first sensory threshold and subjective pain threshold. 4. None of the study medications affected the amplitude or latency of the late SEP components (100-250 ms post-stimulus). The amplitude of early components (15-30 ms post-stimulus) was also unaffected, but aspirin shortened the latency 30 min after ingestion. 5. Sensory detection and pain threshold to electrical skin stimulation were also unaffected by any of the study medications despite subjective central effects with codeine.

The use of third molar surgery in clinical pharmacology

This review discusses the various sequelae that arise after third molar surgery and their use for assessing the efficacy of a variety of therapeutic measures. The surgical procedure provides an opportunity to investigate onset, depth, duration and possible systemic effects of local anaesthetic solutions. Also, the anxiety which often accompanies such surgery lends itself to the appraisal of different anxiolytic agents and sedation techniques. The immediate postoperative sequelae of pain, buccal swelling and trismus provides a useful clinical model for evaluating the efficacy of analgesics and anti-inflammatory drugs. Third molar tooth sockets are susceptible to infection and this propensity enables the assessment of different antibiotic regimens. A further advantage of the third molar model is its application for crossover studies, with the patient acting as their own control. Very few surgical procedures afford this facility, which further adds to the value of this model in clinical pharmacology.

An evaluation of buffered aspirin and aspirin tablets in postoperative pain after third molar surgery

1. Single doses (500 and 1000 mg) of both buffered aspirin and aspirin tablets were compared with placebo in a randomised double-blind trial of parallel design in patients with postoperative pain after third molar surgery. 2. Only buffered aspirin 500 mg provided significant pain relief (P = 0.016) during the 5 h investigation period. 3. A significant correlation (P = 0.004) was observed between overall pain scores after the various aspirin treatments and aspirin esterase activity. 4. Buffered aspirin preparations afforded a slight advantage over aspirin tablets in the control of postoperative pain after third molar surgery. However, the duration of analgesia was short (approximately 2 h). 5. Aspirin esterase activity appears to be an important determinant of the drug's efficacy in postoperative dental pain.

An evaluation of different ibuprofen preparations in the control of postoperative pain after third molar surgery

1. Two separate placebo-controlled studies of parallel design were carried out to evaluate the efficacy of single doses (400 mg) of soluble ibuprofen, ibuprofen liquid in a gelatin capsule and ibuprofen tablets (Nurofen), in patients with postoperative pain after third molar surgery. 2. All ibuprofen preparations provided significant pain relief (P less than 0.05) over a 6 h investigation period. 3. Mean pain scores after ibuprofen tablets and ibuprofen liquid in a gelatin capsule were similar. 4. Soluble ibuprofen 400 mg provided an earlier onset of pain relief (20 min) than ibuprofen tablets (30 min). 5. No unwanted effects were reported in the various ibuprofen treatment groups. 6. The ibuprofen preparations evaluated in this study are effective up to 4 h for controlling postoperative pain after third molar surgery. The soluble form is more efficacious with regard to onset of action.