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). Acute treatment of migraine attacks: efficacy and safety of a nonsteroidal anti-inflammatory drug, diclofenac-potassium, in comparison to oral sumatriptan and placebo. The Diclofenac-K/Sumatriptan Migraine Study Group.
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.
                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.
                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%]).
                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. Migraine attacks are often treated with simple analgesics or with ergotamine-containing preparations alone or in combination with anti-emetics. Although also sometimes used to treat migraine, nonsteroidal anti-inflammatory drugs (NSAIDs) have not been systematically evaluated in controlled clinical trials, particularly in comparison with the newer drug sumatriptan. Sumatriptan is a specific migraine treatment which has recently become among the most widely prescribed acute migraine therapies. However, while effective, it has low oral bioavailability and some problematic adverse effects. Diclofenac-potassium is a potent NSAID available as a fast-acting oral tablet, which has been shown to be safe and effective in several other acute pain indications. In the clinical trial reported here, the efficacy and safety of diclofenac-potassium in the acute treatment of migraine attacks has been tested in comparison with oral sumatriptan and placebo.
                Single oral doses of 50 mg and 100 mg diclofenac-potassium were compared to a single oral dose of 100 mg sumatriptan and placebo in a double-blind randomized crossover trial in 156 adult patients suffering from migraine attacks, with or without aura, selected according to the International Headache Society diagnostic criteria. The primary efficacy criterion was migraine headache pain recorded on a visual analog scale at 2 h after dosing. Secondary endpoints included pain at other time points up to 8 h and the presence of accompanying symptoms (nausea, vomiting, photophobia, phonophobia).
                Diclofenac-potassium was more effective than placebo in reducing migraine headache pain at 2 h after dosing, which was the primary endpoint. Secondary analyses showed that diclofenac-potassium provided significant pain relief from 60 min after dosing and for all remaining endpoints in the 8-h observation period. Both 50 and 100 mg doses of diclofenac-potassium were similarly effective. A similar effect was shown with sumatriptan; however, significant superiority to placebo was seen only from the 90-min time point. Diclofenac-potassium was generally superior to placebo or sumatriptan in reducing accompanying symptoms, particularly nausea. Diclofenac-potassium seemed to be as well tolerated as placebo, with fewer adverse events reported than after sumatriptan treatment and with more patients assessing the overall tolerability of diclofenac-potassium better than that of sumatriptan.
                Compared with placebo and the reference therapy sumatriptan, diclofenac-potassium is an effective, fast-acting, and well-tolerated acute oral therapy for migraine attacks, with advantages over oral sumatriptan in terms of onset of analgesic effect, reduction of accompanying symptoms, and tolerability profile. It may therefore be useful as an alternative oral therapy for migraine attacks.
Oral diclofenac potassium 50 mg is an effective treatment for acute migraine, providing relief from pain and associated symptoms, although only a minority of patients experience pain-free responses. Adverse events are mostly mild and transient and occur at the same rate as with placebo.