Piperazine derivatives of theophylline

Abstract

New compounds of the formula ##STR1## and the pharmaceutically acceptable acid addition salts thereof, wherein Z.sub.1 and Z.sub.2 are each independently selected from the group consisting of CH.sub.2, CHOB and C.dbd.O, wherein B is selected from the group consisting of hydrogen and alkanoyl; Y is oxygen or sulfur; n is an integer from 0-4 but cannot be zero when Z.sub.1 is CHOB; m is an integer from 0-4 but cannot be zero when Z.sub.2 is CHOB; and R.sub.1, R.sub.2 and R.sub.3 are each independently hydrogen, halogen, hydroxy, trifluoromethyl, alkyl or alkoxy; are antihistamines and are therefore useful in the treatment of respiratory diseases including asthma, hay fever, allergies and the common cold.

Dependencies are inferred from the claim text.