Xanax is typically available in lower dosages, such as 0.25mg, 0.5mg, 1mg, and 2mg. Xanax is classified as a benzodiazepine. It acts by enhancing the effects of GABA, a neurotransmitter in the brain that has a calming and inhibitory effect. GABA helps to reduce the excessive activity of nerve cells in the brain, which can lead to anxiety and panic.