Quinoline and quinazoline compounds useful in therapy

Compounds of formula I, wherein R1 represents C1-4 alkoxy optionally substituted by one or more fluorine atoms; R2 represents H or C1-6 alkoxy optionally substituted by one or more fluorine atoms; R3 represents a 5- or 6-membered heterocyclic ring, the ring being optionally substituted; R4 represents a 4-, 5-, 6-, or 7-membered heterocyclic ring, the ring being optionally fused to a benzene ring or a 5- or 6-membered heterocyclic ring, the ring system as a whole being optionally substituted; X represents CH or N; and L is absent, or represents a cyclic group of formula Ia, or represents a chain of formula Ib, and pharmaceutically acceptable salts thereof; are usefull in therapy, in particular in the treatment of benign prostatic hyperplasia.