However, despite the claims of minimal muscarinic receptor activity, anticholinergic side effects may still occur with venlafaxine. Neither parent or metabolite possess monoamine oxidase inhibiting activity. Clinically, improvements in symptoms associated with both major depression and melancholia are observed. Time to peak concentrations can vary, but on average occur at approximately 2 and 4 hours for venlafaxine and ODV, respectively. Metabolism occurs hepatically, with elimination occurring primarily via the urine as unchanged drug, conjugated ODV, ODV, and inactive metabolites.
Individual patients show considerable variability.
Dosage adjustment is necessary in hepatically impaired patients. As with hepatic impairment, individual patients show variability. Venlafaxine is classified as pregnancy category C. Use of this agent in pregnant women should be undertaken only if clearly needed. Also, caution should be observed when administering this agent to breast-feeding women because it is unknown whether venlafaxine or its metabolites distribute into breast milk. Administration of venlafaxine to patients with preexisting hepatic disease or renal impairment should be done cautiously because the drug is hepatically metabolized, and venlafaxine and its metabolites are renally eliminated.