Venlafaxine is an antidepressant (an SNRI) that works on brain chemicals, while vitamin B12 is a water-soluble vitamin used by the body for nerve health and red blood cell production. They are processed by the body through different pathways and do not interfere with each other's absorption, metabolism, or effectiveness.
This is a companion discussion topic for the original article at https://patient.info/medication-interactions/venlafaxine-krka-and-vitamin-b12-interaction