Aptazapine is a “non-classic” tetracyclic antidepressant drug. Compound bears a structural resemblance to mianserin. Aptazapine possesses a high degree of potency and selectivity for central alpha-2, as opposed to alpha-1, adrenoceptors. Aptazapine failed to inhibit in vitro uptake of norepinephrine or serotonin to an appreciable extent. However, it exhibited a moderate ability to compete for 5-HT2 receptor binding in calf frontal cortex, as measured by displacement of 3H-spiroperidol. Another property apparently shared with other antidepressants is the ability of aptazapine to inhibit histamine-activated adenyl cyclase. As centrally acting alpha-2 adrenoceptor antagonists, aptazapine significantly suppressed cataplexy, a major symptom of narcolepsy, in Doberman pinschers.