Home » Ortho Related » Medications » Alprazolm/Xanax Alprazolm/Xanax Discussion for anxiety disorders, benzodiazepine, cross tolerant w/ ETOH; Adult: 0.25-0.5mg PO tid; max dose= 4mg/day; reduce dose in elderly; Peak plasma PO [ in 1-2hr w/ t/2== 6-20 hr