PHARMACOLOGY OF THE NEW REVERSIBLE INHIBITOR OF MONOAMINE-OXIDASE-A, RS-8359

RS-8359 is a new reversible inhibitor of monoamine oxidase A (RIMA). W ith a selectivity ratio of about 2200 for the A:B enzyme types, it is one of the most specific of this class of compounds. As a result, it s hows relatively little effect upon blood pressure when administered to gether with tyramine, thus effectively eliminating the `cheese' effect which has contributed to the limited clinical use of the classical mo noamine oxidase inhibitors (MAOIs). RS-8359 shows little affinity for the common central nervous system receptors and little anticholinergic effect. These characteristics suggest a relatively benign adverse eve nt profile, which may be particularly advantageous in the elderly and may generally contribute to patient acceptance and compliance. In term s of its effects upon serotonin (5-hydroxytryptamine), RS-8359 gives i ncreases similar to those of other MAOIs with activity sustained for a bout 9 h. In behavioural investigations, the compound gives results si milar to those found with several antidepressants widely used in the c linic. Overall, the pharmacology of RS-8359 indicates that it should h ave antidepressant activity in man.