| abstract |
A tetracyclic compound of the formula: <IMAGE> wherein A and the atoms to which it is attached and the optional double bond represent a mono- or di-heterocyclic ring selected from: <IMAGE> <IMAGE> wherein R1, R2, R3, R4 and X are specifically defined, which compounds are useful in the treatment of dopamine-related neurological, psychological and cardiovascular disorders as well as in the treatment of substance abuse and other addictive behavior disorders, cognitive impairment and attention deficit disorder. |