8-substituted anthines as phosphodiesterase inhibitors

Abstract From the Canadian patent

A compound of formula (I) or if appropriate a pharmaceutically acceptable salt thereof, wherein R1 and R2 each independently represent a moiety of formula (a): -(CH2)m-A wherein m represents zero or an integer 1, 2 or 3 and A represents a substituted or unsubstituted cyclic hydrocarbon radical; R3 represents hydrogen, substituted or unsubstituted alkyl or an aralkyl group substituted or unsubstituted in the aryl moiety; and R4 represents hydrogen, alkyl or alkylcarbonyl; a process for preparing such a compound, a pharmaceutical composition containing such a compound and the use of such a compound in medicine.