clonidine hydrochloride /klō″nədēn/ , an alpha2-agonist used as an antihypertensive. It stimulates alpha2-adrenergic receptors in the brainstem to decrease sympathetic nervous system outflow. It is also administered epidurally to treat pain. ▪ INDICATIONS: It is prescribed alone or in combination for the reduction of high blood pressure and is an adjunct for the treatment of cancer pain when pain persists during intraspinal opiate treatments. It may be used in the treatment of attention deficit hyperactivity disorder (ADHD) when a patient cannot tolerate or does not respond to stimulants or antidepressants. ▪ CONTRAINDICATIONS: Known hypersensitivity to this drug prohibits its use. ▪ ADVERSE EFFECTS: Among the more serious adverse reactions is a withdrawal syndrome that occurs on discontinuation of the medication characterized by tachycardia, a rapid increase in blood pressure, and anxiety. Drowsiness, sexual dysfunction, and dry mouth commonly occur.