• Abortive treatment dominated by triptans
• Imigran/Imitrex sales grown to $1.2 billion p.a. (market leader) since US launch in 1996
• Major opportunity in prophylactic treatment: Johnson & Johnson’s Topamax has US sales that now exceed $1billion p.a. for migraine treatment.

What causes migraines?

According to the International Headache Society (IHS) migraine is a common disabling primary headache with high socioeconomic and personal costs. Migraine is characterised by recurrent episodic attacks of head pain which is sometimes accompanied by symptoms such as nausea, light and/or sound sensitivity, fatigue, and sensitivity to head movements.

While the mechanisms by which migraines develop are not wholly understood, recent research is starting to link underlying abnormalities of brain function to the symptoms experienced by migraineurs. Changes in the firing patterns of neurons are now thought likely to be the trigger for migraine attacks, possibly acting via the phenomenon of Cortical Spreading Depression, to cause stimulation of the trigeminal cranial nerve. Activation of this nerve produces well understood vascular and neuronal changes resulting in the release of inflammatory mediators leading to activation of pain pathways and the characteristic pain of a migraine. Triptans such as sumatriptan act to reverse these latter effects and thus mitigate migraine headache.