Patent ID: 8513027

Claim:
A method for identifying an EP 4 receptor antagonist, which antagonist inhibits prostaglandin-induced relaxation of cerebral blood vessels having a diameter of less than 1 mm by selectively preventing the relaxation of cerebral vessels of less than 1 mm diameter, wherein said method comprises: (a) providing an EP 4 receptor together with at least one other receptor selected from the group of EP 1 , EP 2 and EP 3 receptors; (b) bringing a potential antagonist into contact with said receptors; (c) determining whether said potential antagonist is an EP 4 receptor antagonist having a binding affinity for the EP 4 receptor at least 10-fold higher than for said EP 1 , EP 2 and/or EP 3 receptors; and (d) selecting the EP 4 receptor antagonist which so binds as an agent for the treatment of primary headache disorder or drug-induced headache; wherein said EP 4 receptor is provided in the form of isolated vasculature from a cerebral artery.