|Central-Acting α-Adrenergic Agonist||Clonidine (Catapres)|
Clonidine patch (Catapres-TTS)
|Reduce sympathetic outflow from CNS.|
Reduce peripheral sympathetic tone, produces vasodilation, and decreases SVR and BP.
|Sudden discontinuation may cause withdrawal syndrome, including rebound hypertension, tachycardia, headache, tremors, apprehension, sweating.|
Chewing gum or hard candy may relieve dry mouth.
Alcohol and sedatives increase sedation. Transdermal patch may be related to fewer side effects and better adherence.
|Same as clonidine, but not available in transdermal formulation.|
|Methyldopa||Instruct patient about daytime sedation and avoidance of hazardous activities. |
Taking a single daily dose at bedtime minimizes sedative effect.
|Peripheral-Acting α-Adrenergic Agonist||Reserpine||Depletes central and peripheral stores of norepinephrine. Results in peripheral vasodilation (decreases SVR and BP).||Must be given twice daily. Contraindicated in patients with history of depression. Monitor mood and mental status regularly. |
Advise patient to avoid barbiturates, alcohol, opioids.
|α1-Adrenergic Blockers||Doxazosin (Cardura)|
|Block 1-adrenergic effects, producing peripheral vasodilation (decreases SVR and BP). Beneficial effects on lipid profile.||Reduced resistance to the outflow of urine in benign prostatic hyperplasia. Taking drug at bedtime reduces risks associated with orthostatic hypotension.|
|Phentolamine (Regitine)||Blocks 1-adrenergic receptors, resulting in peripheral vasodilation (decreases SVR and BP).||Used in short-term management of pheochromocytoma. Also used locally to prevent necrosis of skin and subcutaneous tissue after extravasation of adrenergic drug. |
No oral formulation.
|βAdrenergic Blockers||Cardioselective Blockers |
|Cardioselective agents block β1– adrenergic receptors. Reduce BP by blocking –adrenergic effects. Decrease CO and reduce sympathetic vasoconstrictor tone. Decrease renin secretion by kidneys.||Monitor pulse and BP regularly. Use with caution in patients with diabetes because drug may depress the tachycardia associated with hypoglycemia and may adversely affect glucose metabolism.|
Drug of choice for patients with a history of an MI or heart failure. Less effective BP reduction in African American patients. Esmolol is for IV use only.
Cardioselective agents lose cardioselectivity at higher doses.
|Nonselective agents block β1– and β2-adrenergic receptors. Reduce BP by blocking β1– and β2-adrenergic effects.||Same as cardioselective, except nonselective agents may cause bronchospasm, especially in patients with a history of asthma.|
|Mixed α and βBlockers||Carvedilol (Coreg)|
|α1-, β1-, and β2-adrenergic blocking properties producing peripheral vasodilation and decreased heart rate. Reduce CO, SVR, and BP.||Same as -blockers. IV form available for hypertensive crisis in hospitalized patients. Patients must be kept supine during IV administration. |
Assess patient tolerance of upright position (severe orthostatic hypotension) before allowing upright activities (e.g., commode).
|Direct Vasodilators||Fenoldopam (Corlopam)||Activates dopamine receptors, resulting in systemic and renal vasodilation.||IV use only for hypertensive crisis in hospitalized patients. |
Use cautiously in patients with glaucoma. Patient should remain flat for 1 hr after administration.
|Hydralazine||Reduces SVR and BP by direct arterial vasodilation.||IV use for hypertensive crisis in hospitalized patients. Twice-daily oral dosage. Not used as monotherapy because of side effects. |
Contraindicated in patients with coronary artery disease.
|Minoxidil||Reduces SVR and BP by direct arterial vasodilation.||Reserved for treatment of severe hypertension associated with renal failure and resistant to other therapy. Once- or twice-daily dosage.|
|Nitroglycerin||Relaxes arterial and venous smooth muscle, reducing preload and SVR. At low dose, venous dilation predominates; at higher dose, arterial dilation is present.||IV use for hypertensive crisis in hospitalized patients with myocardial ischemia. |
Given by continuous IV infusion with pump or control device.
|Sodium nitroprusside||Direct arterial vasodilation reduces SVR and BP.||IV use for hypertensive crisis in hospitalized patients. Given by continuous IV infusion with pump or control device. |
Arterial monitoring of BP recommended. Wrap IV solutions with an opaque material to protect from light. Stable for 24 hr.
Metabolized to cyanide, then thiocyanate. Monitor thiocyanate levels with prolonged use (>3 days) or doses ≥4 mcg/kg/min.