Evidence for the use of non-steroidal anti-inflammatory drugs for acute pain in the post anaesthesia care unit

Multimodal Analgesia, Current Concepts, and Acute Pain Considerations

PURPOSE OF REVIEW

Management of acute pain following surgery using a multimodal approach is recommended by the American Society of Anesthesiologists whenever possible. In addition to opioids, drugs with differing mechanisms of actions target pain pathways resulting in additive and/or synergistic effects. Some of these agents include alpha 2 agonists, NMDA receptor antagonists, gabapentinoids, dexamethasone, NSAIDs, acetaminophen, and duloxetine.

RECENT FINDINGS

Alpha 2 agonists have been shown to have opioid-sparing effects, but can cause hypotension and bradycardia and must be taken into consideration when administered. Acetaminophen is commonly used in a multimodal approach, with recent evidence lacking for the use of IV over oral formulations in patients able to take medications by mouth. Studies involving gabapentinoids have been mixed with some showing benefit; however, future large randomized controlled trials are needed. Ketamine is known to have powerful analgesic effects and, when combined with magnesium and other agents, may have a synergistic effect. Dexamethasone reduces postoperative nausea and vomiting and has been demonstrated to be an effective adjunct in multimodal analgesia. The serotonin-norepinephrine reuptake inhibitor, duloxetine, is a novel agent, but studies are limited and further evidence is needed. Overall, a multimodal analgesic approach should be used when treating postoperative pain, as it can potentially reduce side effects and provide the benefit of treating pain through different cellular pathways.

Single dose oral analgesics for acute postoperative pain in adults - an overview of Cochrane reviews

BACKGROUND

This is an updated version of the original Cochrane overview published in Issue 9, 2011. That overview considered both efficacy and adverse events, but adverse events are now dealt with in a separate overview.Thirty-nine Cochrane reviews of randomised trials have examined the analgesic efficacy of individual drug interventions in acute postoperative pain. This overview brings together the results of those individual reviews and assesses the reliability of available data.

OBJECTIVES

To summarise the efficacy of pharmaceutical interventions for acute pain in adults with at least moderate pain following surgery who have been given a single dose of oral analgesic.

METHODS

We identified systematic reviews in the Cochrane Database of Systematic Reviews in The Cochrane Library through a simple search strategy. All reviews were overseen by a single review group, had a standard title, and had as their primary outcome the number of participants with at least 50% pain relief over four to six hours compared with placebo. For individual reviews, we extracted the number needed to treat for an additional beneficial outcome (NNT) for this outcome for each drug/dose combination, and also the percentage of participants achieving at least 50% maximum pain relief, the mean of mean or median time to remedication, and the percentage of participants remedicating by six, eight, 12, or 24 hours. Where there was adequate information for pairs of drug and dose (at least 200 participants, in at least two studies), we defined the addition of four comparisons of typical size (400 participants in total) with zero effect as making the result potentially subject to publication bias and therefore unreliable.

MAIN RESULTS

The overview included 39 separate Cochrane Reviews with 41 analyses of single dose oral analgesics tested in acute postoperative pain models, with results from about 50,000 participants in approximately 460 individual studies. The individual reviews included only high-quality trials of standardised design, methods, and efficacy outcome reporting. No statistical comparison was undertaken.Reliable results (high quality information) were obtained for 53 pairs of drug and dose in painful postsurgical conditions; these included various fixed dose combinations, and fast acting formulations of some analgesics. NNTs varied from about 1.5 to 20 for at least 50% maximum pain relief over four to six hours compared with placebo. The proportion of participants achieving this level of benefit varied from about 30% to over 70%, and the time to remedication varied from two hours (placebo) to over 20 hours. Good (low) NNTs were obtained with ibuprofen 200 mg plus paracetamol (acetaminophen) 500 mg (NNT compared with placebo 1.6; 95% confidence interval 1.5 to 1.8), ibuprofen fast acting 200 mg (2.1; 1.9 to 2.3); ibuprofen 200 mg plus caffeine 100 mg (2.1; 1.9 to 3.1), diclofenac potassium 50 mg (2.1; 1.9 to 2.5), and etoricoxib 120 mg (1.8; 1.7 to 2.0). For comparison, ibuprofen acid 400 mg had an NNT of 2.5 (2.4 to 2.6). Not all participants had good pain relief and, for many pairs of drug and dose, 50% or more did not achieve at least 50% maximum pain relief over four to six hours.Long duration of action (eight hours or greater) was found for etoricoxib 120 mg, diflunisal 500 mg, paracetamol 650 mg plus oxycodone 10 mg, naproxen 500/550 mg, celecoxib 400 mg, and ibuprofen 400 mg plus paracetamol 1000 mg.There was no evidence of analgesic effect for aceclofenac 150 mg, aspirin 500 mg, and oxycodone 5 mg (low quality evidence). No trial data were available in reviews of acemetacin, meloxicam, nabumetone, nefopam, sulindac, tenoxicam, and tiaprofenic acid. Inadequate amounts of data were available for nine drugs and doses, and data potentially susceptible to publication bias for 13 drugs and doses (very low quality evidence).

AUTHORS' CONCLUSIONS

There is a wealth of reliable evidence on the analgesic efficacy of single dose oral analgesics. Fast acting formulations and fixed dose combinations of analgesics can produce good and often long-lasting analgesia at relatively low doses. There is also important information on drugs for which there are no data, inadequate data, or where results are unreliable due to susceptibility to publication bias. This should inform choices by professionals and consumers.

Analgesic efficacy and safety of a novel injectable formulation of diclofenac compared with intravenous ketorolac and placebo after orthopedic surgery: a multicenter, randomized, double-blinded, multiple-dose trial

OBJECTIVES

A novel injectable formulation of diclofenac, Dyloject, utilizes hydroxypropyl-β-cyclodextrin (HPβCD) as a solubilizing agent, allowing dosing as a small-volume intravenous bolus for postoperative pain. In this test of the efficacy and safety of HPβCD diclofenac, we hypothesized that HPβCD diclofenac would relieve moderate and severe pain after orthopedic surgery.

PATIENTS AND METHODS

Adults 18 to 85 years old with moderate and severe pain within 6 hours after surgery were randomized to HPβCD diclofenac, ketorolac tromethamine, or placebo, and stratified by risk cohort. The HPβCD diclofenac non-high-risk cohort dose was 37.5 mg, the high-risk cohort received 18.75 mg, and patients ≥95 kg received 50 mg. The ketorolac dose was 30 mg in the non-high-risk and high-weight cohorts and 15 mg in the high-risk cohort. Rescue intravenous morphine was given for pain as needed. Efficacy was measured by the sum of pain intensity differences (SPID).

RESULTS

Mean SPID scores of 277 patients were significantly better with HPβCD diclofenac and ketorolac than with placebo (P<0.0001), across all risk cohorts (P<0.05). HPβCD diclofenac was associated with better SPID scores, faster onset of analgesia, and significantly lower opioid requirement (P<0.008) than ketorolac. In patients more than or equal to 65 years, HPβCD diclofenac was associated with significantly better analgesic efficacy (P=0.05), and lower opioid requirement versus ketorolac. The incidence of treatment-related adverse events was similar across groups.

DISCUSSION

HPβCD diclofenac is safe and efficacious for acute moderate and severe pain after orthopedic surgery and significantly spares morphine use.

Safety of a novel parenteral formulation of diclofenac after major orthopedic or abdominal/pelvic surgery in a population including anticoagulated, elderly or renally insufficient patients: an open-label, multiday, repeated dose clinical trial

OBJECTIVE

Decisions to use or avoid nonsteroidal anti-inflammatory drugs (NSAIDs) for postsurgical pain are often influenced by concerns about bleeding and renal adverse effects. The objective of this study was to evaluate the safety of a novel parenteral NSAID, hydroxypropyl-β-cyclodextrin (HPβCD) diclofenac, in a large postsurgical patient population, with particular focus on bleeding and renal effects.

METHODS

This was a large open-label study in adult patients with acute moderate-to-severe pain following major surgery. Patients received ≥2 days of continuous treatment with HPβCD diclofenac, administered as a small-volume bolus injection every 6 hours. Few exclusion criteria were applied in order to reflect surgical patient populations commonly managed in clinical practice. Adverse events (AEs) were recorded throughout the study. The incidences of bleeding- and renal-related AEs were examined in patient subpopulations with known risk factors for NSAID-induced complications: advanced age, pre-existing renal insufficiency, concomitant anticoagulant use, prolonged exposure, elevated dosage, and major surgeries.

RESULTS

Of the total 971 patients studied, 38% were ≥65 years old (12% >75 years), 62% received concomitant anticoagulants, and 6% had pre-existing renal insufficiency. HPβCD diclofenac was well tolerated by the patient population. AE rates are presented by risk factor to enable clinicians to better describe renal- or bleeding-related AEs.

CONCLUSIONS

In addition to its previously demonstrated efficacy, this study provides evidence of HPβCD diclofenac's safety in a large postsurgical population including anticoagulated, elderly or renally insufficient patients. Because study exclusion criteria were minimal, these findings may be broadly generalizable to populations commonly treated in clinical practice.

Single dose oral analgesics for acute postoperative pain in adults

BACKGROUND

Thirty-five Cochrane Reviews of randomised trials testing the analgesic efficacy of individual drug interventions in acute postoperative pain have been published. This overview brings together the results of all those reviews and assesses the reliability of available data.

OBJECTIVES

To summarise data from all Cochrane Reviews that have assessed the effects of pharmaceutical interventions for acute pain in adults with at least moderate pain following surgery, who have been given a single dose of oral analgesic taken alone.

METHODS

We identified systematic reviews in The Cochrane Library through a simple search strategy. All reviews were overseen by a single Review Group, had a standard title, and had as their primary outcome numbers of participants with at least 50% pain relief over four to six hours compared with placebo. For individual reviews we extracted the number needed to treat (NNT) for this outcome for each drug/dose combination, and also the percentage of participants achieving at least 50% maximum pain relief, the mean of mean or median time to remedication, the percentage of participants remedicating by 6, 8, 12, or 24 hours, and results for participants experiencing at least one adverse event.

MAIN RESULTS

The overview included 35 separate Cochrane Reviews with 38 analyses of single dose oral analgesics tested in acute postoperative pain models, with results from about 45,000 participants studied in approximately 350 individual studies. The individual reviews included only high-quality trials of standardised design and outcome reporting. The reviews used standardised methods and reporting for both efficacy and harm. Event rates with placebo were consistent in larger data sets. No statistical comparison was undertaken.There were reviews but no trial data were available for acemetacin, meloxicam, nabumetone, nefopam, sulindac, tenoxicam, and tiaprofenic acid. Inadequate amounts of data were available for dexibuprofen, dextropropoxyphene 130 mg, diflunisal 125 mg, etoricoxib 60 mg, fenbufen, and indometacin. Where there was adequate information for drug/dose combinations (at least 200 participants, in at least two studies), we defined the addition of four comparisons of typical size (400 participants in total) with zero effect as making the result potentially subject to publication bias and therefore unreliable. Reliable results were obtained for 46 drug/dose combinations in all painful postsurgical conditions; 45 in dental pain and 14 in other painful conditions.NNTs varied from about 1.5 to 20 for at least 50% maximum pain relief over four to six hours compared with placebo. The proportion of participants achieving this level of benefit varied from about 30% to over 70%, and the time to remedication varied from two hours (placebo) to over 20 hours in the same pain condition. Participants reporting at least one adverse event were few and generally no different between active drug and placebo, with a few exceptions, principally for aspirin and opioids.Drug/dose combinations with good (low) NNTs were ibuprofen 400 mg (2.5; 95% confidence interval (CI) 2.4 to 2.6), diclofenac 50 mg (2.7; 95% CI 2.4 to 3.0), etoricoxib 120 mg (1.9; 95% CI 1.7 to 2.1), codeine 60 mg + paracetamol 1000 mg (2.2; 95% CI 1.8 to 2.9), celecoxib 400 mg (2.5; 95% CI 2.2 to 2.9), and naproxen 500/550 mg (2.7; 95% CI 2.3 to 3.3). Long duration of action (≥ 8 hours) was found for etoricoxib 120 mg, diflunisal 500 mg, oxycodone 10 mg + paracetamol 650 mg, naproxen 500/550 mg, and celecoxib 400 mg.Not all participants had good pain relief and for many drug/dose combinations 50% or more did not achieve at last 50% maximum pain relief over four to six hours.

AUTHORS' CONCLUSIONS

There is a wealth of reliable evidence on the analgesic efficacy of single dose oral analgesics. There is also important information on drugs for which there are no data, inadequate data, or where results are unreliable due to susceptibility to publication bias. This should inform choices by professionals and consumers.