NCLEX Review Guide: Centrally Acting Sympatholytics (Adrenergic Blockers)

Centrally Acting Sympatholytics

• Centrally acting sympatholytics work by stimulating alpha-2 receptors in the brain's medullary vasomotor center, reducing sympathetic outflow and decreasing blood pressure.
• Primary medications include clonidine (Catapres), methyldopa (Aldomet), and guanfacine (Tenex).
• These medications reduce heart rate, cardiac output, and peripheral vascular resistance through central nervous system action.

Clonidine (Catapres)

• Available in oral, transdermal patch, and injectable forms for versatile administration options.
• Never discontinue abruptly - can cause severe rebound hypertension within 12-48 hours.
• Also used for ADHD, opioid withdrawal, and menopausal hot flashes as off-label applications.

Methyldopa (Aldomet)

• Preferred antihypertensive during pregnancy due to proven safety profile for mother and fetus.
• Can cause positive Coombs test and hemolytic anemia as serious adverse effects requiring monitoring.
• Hepatotoxicity risk requires periodic liver function test monitoring during therapy.

Assessment & Monitoring

1. Monitor blood pressure and heart rate before and after administration
2. Assess for signs of orthostatic hypotension, especially during initial therapy
3. Evaluate liver function tests for methyldopa patients
4. Monitor for signs of depression or sedation

Critical Patient Teaching

• Never stop medication abruptly - must taper gradually to prevent life-threatening rebound hypertension.
• Change positions slowly to minimize orthostatic hypotension and fall risk, especially in elderly patients.
• Avoid alcohol and CNS depressants as they potentiate sedative effects and increase fall risk.
• Report signs of depression, unusual fatigue, or liver problems (yellowing, dark urine) immediately.