Efficacy and tolerability of a new powdered formulation of diclofenac potassium for oral solution for the acute treatment of migraine: results from the International Migraine Pain Assessment Clinical Trial (IMPACT)

OBJECTIVE

This study assessed the efficacy of diclofenac potassium for oral solution, a novel water-soluble buffered powder formulation, versus placebo for the acute treatment of migraine. Diclofenac potassium for oral solution has a time to maximum plasma concentration (Tmax) of 15 minutes, suggesting the potential for a rapid onset of therapeutic effects.

METHODS

This was a randomized, double-blind, parallel-group, placebo-controlled study conducted in 23 US centers. Adult sufferers with an established migraine diagnosis according to the International Classification of Headache Disorders, second edition (ICHD-II), treated one moderate or severe attack with 50 mg diclofenac potassium for oral solution (dissolved in approximately 2 ounces of water; N=343) or matching placebo (N=347). Four co-primary endpoints included the percentage of subjects who at two hours post-treatment reported no headache pain, no nausea, no photophobia and/or no phonophobia.

RESULTS

Significantly more subjects treated with diclofenac potassium for oral solution (N=343) achieved a two-hour pain-free response (25% vs. 10%, p<.001), no nausea (65% vs. 53%; p=.002), no photophobia (41% vs. 27%; p<.001) and no phonophobia (44% vs. 27%; p<.001) compared to placebo. Pain intensity differences between treatments were significantly lower in the diclofenac potassium oral solution group, starting at 30 minutes post-treatment (p=.013) with significant differences at all time points thereafter (p<.001). Twenty-four-hour sustained pain-free response favored diclofenac potassium oral solution treatment versus placebo (19% vs. 7%, p<.0001). The most common adverse event considered to be treatment related was nausea (diclofenac potassium for oral solution [4.6%]; placebo [4.3%]).

CONCLUSIONS

This study shows that this formulation of diclofenac potassium for oral solution is effective in reducing pain intensity within 30 minutes, which may be related to the 15-minute T(max) associated with this formulation. The rapid-onset benefits were sustained through 24 hours post-treatment.

Single dose piroxicam for acute postoperative pain

BACKGROUND

Piroxicam is a non-steroidal anti-inflammatory drug (NSAID) with analgesic properties, and is used mainly for treating rheumatic disorders. Some drugs have been directly compared against each other within a trial setting to determine their relative efficacies, whereas other have not. It is possible, however, to compare analgesics indirectly by examining the effectiveness of each drug against placebo when used in similar clinical situations.

OBJECTIVES

To determine the analgesic efficacy and adverse effects of single-dose piroxicam compared with placebo in moderate to severe postoperative pain. To compare the effects of piroxicam with other analgesics.

SEARCH STRATEGY

Published reports were identified from systematic searching of Medline, Biological Abstracts, Embase, The Cochrane Library and the Oxford Pain Relief Database. Additional studies were identified from the reference lists of retrieved reports.

SELECTION CRITERIA

The following inclusion criteria were used: full journal publication, randomised placebo controlled trial, double-blind design, adult patients, postoperative pain of moderate to severe intensity at the baseline assessment, postoperative administration of oral or intramuscular piroxicam.

DATA COLLECTION AND ANALYSIS

Summed pain intensity and pain relief data were extracted and converted into dichotomous information to yield the number of patients obtaining at least 50% pain relief. This was used to calculate estimates of relative benefit and number-needed-to-treat for one patient to obtain at least 50% pain relief. Information was collected on adverse effects and estimates of relative risk and number-needed-to-harm were calculated.

MAIN RESULTS

Three trials (141 patients) compared oral piroxicam 20 mg with placebo and one (15 patients) compared oral piroxicam 40 mg with placebo. For single doses of piroxicam 20 mg and 40 mg the respective numbers-needed-to-treat for at least 50% pain relief were 2.7 (2.1 to 3.8) [95% confidence interval] and 1.9 (1.2 to 4.3) [95% confidence interval] compared with placebo over 4-6 hours in moderate to severe postoperative pain. The reported incidence of adverse effects was no higher with piroxicam (20 mg or 40 mg) than with placebo.

REVIEWER'S CONCLUSIONS

Piroxicam appears to be of similar efficacy to other non-steroidal anti-inflammatory drugs (NSAIDs) and intramuscular morphine 10 mg when used as a single oral dose in the treatment of moderate to severe postoperative pain.