Used primarily in the treatment of high blood pressure and certain psychiatric disorders, especially in managing symptoms of schizophrenia and anxiety. It works by depleting neurotransmitters like norepinephrine, dopamine, and serotonin from nerve endings, which results in reduced sympathetic activity, leading to lower heart rate and blood pressure. Historically significant as one of the first effective antipsychotic and antihypertensive agents, it has largely been replaced by newer drugs with fewer side effects but remains in use in specific cases, particularly in resource-limited settings due to its low cost and long-acting profile. Also used in research to study neurotransmitter depletion and its effects on behavior and cardiovascular function.