Dexmedetomidine hydrochloride (like brand names Precedex) is a potent sedative, analgesic, and anxiolytic drug, primarily used intravenously for sedation in ICU patients or before/during procedures, working by activating alpha-2 adrenergic receptors to decrease norepinephrine release, leading to calm, drowsy states without significant respiratory depression, but can cause blood pressure changes (transient hypertension/hypotension) and slow heart rate.