The NSAID diclofenac is a potent inhibitor of prostaglandin synthesis and an established antipyretic and analgesic agent. Diclofenac-potassium was developed as an immediate-release tablet with the aim of providing rapid onset of action after oral administration. This formulation has been investigated in the acute treatment of migraine. Data from available placebo-controlled clinical trials indicate that diclofenac-potassium 50 or 100mg as an immediate-release tablet is more effective than placebo and as effective as oral sumatriptan 100mg and ergotamine plus caffeine at reducing pain intensity in patients with migraine 2 hours after initial administration. Duration of pain relief is similar for the 3 drugs but onset appears to be faster with diclofenac-potassium than with oral sumatriptan or ergotamine plus caffeine. Diclofenac-potassium appears to have favourable effects on some accompanying symptoms such as nausea and vomiting. The frequency of these symptoms was significantly lower with diclofenac-potassium than with sumatriptan in 1 study, although only a few patients had vomiting at baseline. Effects on phonophobia or photophobia did not differ between diclofenac-potassium, sumatriptan and ergotamine plus caffeine. The need for rescue medication is consistently less with diclofenac-potassium than with placebo. Data are inconsistent or scarce regarding the effects of diclofenac-potassium versus placebo on other measures such as headache recurrence and working ability. Diclofenac-potassium was generally well tolerated in clinical trials in patients with migraine. Adverse events reported most frequently (abdominal pain, tiredness and fatigue and nausea) were typically mild to moderate.
Conclusion: Diclofenac-potassium provides rapid pain relief (within 60 to 90 minutes), is well tolerated and reduces the frequency of some of the accompanying symptoms in patients with migraine. Available trials indicate that diclofenac-potassium provides similar pain relief to sumatriptan and is at least as effective as ergotamine plus caffeine, but appears to have a greater effect on nausea and vomiting than sumatriptan and a faster onset of action than both drugs. Comparisons with other NSAIDs are lacking. Diclofenac-potassium is likely to find a role as a useful first-line option in the acute treatment of migraine.