Chiral resolution and binding study of 1,3,4,14b-tetrahydro-2,10-dimethyl-2H,10H-pyrazino[2,1-d]pyrrolo[1,2-b] [1,2,5]benzotriazepine (10-methyl-10-azaaptazepine) and 2-methyl-1,3,4,14b-tetrahydro-2H-pyrazino[2,1-d]pyrrolo[1,2-b] [1,2,5]benzothiadiazepine 10,10-dioxide (tiaaptazepine).

The affinities of the enantiomers of 1,3,4,14b-tetrahydro-2,10-dimethyl-2H,10H-pyrazino[2,1-d]pyrrolo[1,2-b] [1,2,5]benzotriazepine (10-methyl-10-azaaptazepine, 5) and 2-methyl-1,3,4,14b-tetrahydro-2H-pyrazino[2,1-d]pyrrolo[1,2-b] [1,2,5]benzothiadiazepine 10,10-dioxide (tiaaptazepine, 6) were evaluated in receptor binding assays. Compound (+)-(S)-5, the most significant tested enantiomer, showed good affinities for 5-HT1A, 5-HT2A 5-HT2C and alpha2NA receptors, moderate affinities for DA1, DA3r and 5-HT3 receptors and it was devoid of affinity for DA2, alpha(1NA) and muscarinic receptors. Compound (+)-(S)-5 showed an interesting pharmacological profile different from those of the reference compounds mirtazepine, mianserin and 6-methoxymianserin.