A pharmacological approach to the analgesizing mechanism of somatostatin in cluster headache.

Vasodilation, conjunctival and nasal edema as well as miosis are symptoms associated with cluster headache (CH) attacks. Similar symptomatology is caused by substance P (SP) release from peripheral trigeminal nerve endings. The symptomatic effect of somatostatin (SRIF) during CH attacks was attributed to the inhibition of SP release from trigeminal neurons. This study was designed to evaluate both the vascular effect of SRIF on the dorsal hand vein and SRIF plasma levels prior to and after subcutaneous and intranasal administration in CH patients. A powerful venoconstriction and tachyphylaxis were demonstrated when SRIF was administered both as bolus and infusion. Plasma levels of SRIF in CH sufferers were lower than in control subjects. Subcutaneous and intranasal SRIF administrations induced maximal plasma levels after 5 and 10 min, respectively. These data suggest that SRIF plays an important role during CH attacks; however, its exact mechanism of action is still to be defined.