Clonidine & Alpha-1 Blockers

Clonidine and alpha-1 blockers are antihypertensives that act on the sympathetic nervous system: clonidine is a central alpha-2 agonist that reduces sympathetic outflow from the brain, and alpha-1 blockers such as prazosin, doxazosin and terazosin dilate blood vessels and relax the prostate. Clonidine causes drowsiness, dry mouth, orthostatic hypotension and a slower heart rate, so the nurse checks blood pressure and pulse before each dose. Its key rule is never stopping it abruptly, because rebound hypertension can follow; it is tapered, and the client must not skip doses or run out. The clonidine patch is changed every 7 days at a new site and removed before an MRI. Alpha-1 blockers cause first-dose orthostatic hypotension and syncope (fainting), so the first dose, each increase and any restart are given at bedtime, and the client rises slowly. Tamsulosin is prostate-selective and used only for BPH, and the client tells the eye surgeon about it before cataract surgery because of floppy iris syndrome. Blood pressure drops further with sildenafil or tadalafil.