] Discontinuation syndrome Main article: Discontinuation of Venlafaxine In vitro studies revealed that venlafaxine has virtually no affinity for opiate, benzodiazepine, or N-methyl-D-aspartic acid ( NMDA ) receptors. It has no significant CNS stimulant activity in rodents. In primate drug discrimination studies, venlafaxine showed no significant stimulant or depressant abuse liability.