N,N,O-Tridesmethylvenlafaxine is a key metabolite of the antidepressant venlafaxine. It is primarily employed in pharmacological research to investigate metabolic pathways, drug interactions, and the pharmacokinetics of serotonin-norepinephrine reuptake inhibitors (SNRIs). This compound aids in understanding neurotransmitter modulation and is commonly used as an analytical reference standard for developing and validating methods to quantify venlafaxine metabolites in biological samples, such as plasma or urine.