INDOLES

Novel indoles of the general formula (I): wherein R1 represents hydrogen, alkyl, cycloalkyl, alkenyl, phenyl or phenyl alkyl in which the phenyl ring may be unsubstituted or substituted by one or two substituents selected from alkoxy, hydroxy, halogen, a group R5R6NCO- where R5 and R6 each represents hydrogen or alkyl, or a group R7R8N-, where R7 and R8 each represents hydrogen or alkyl, or R7R8N- represents a saturated monocyclic 5- to 7- membered ring; R2 represents hydrogen or alkyl; or R1 and R2 together with the nitrogen atom form a saturated monocyclic 5- to 7-membered ring; R3 and R4 each represents hydrogen, alkyl or a 2-propenyl group; and n is an integer from 2 to 5; and physiologically acceptable salts and solvates thereof have selective vasoconstrictor activity and are useful in treating and/or preventing pain resulting from dilatation of the cranial vasculature, in particular migraine.