SSRIs and SNRIs like venlafaxine and sertraline are well known to cause hyponatremia. Usually considered safe, this adverse drug event can lead to weakness, confusion, seizure and even cerebral edema. Elderly are more susceptible to this adverse effect.
ADH is regulated by serotonin and thus the mechanism for the Hyponatremia is SIADH.
Tolvaptan, a vasopressin receptor antagonist, has been a new treatment that has been used anecdotally in Europe. Waiting for the first US case report.