Combining Antihypertensive Drugs

An antihypertensive drug can be used alone or in combination with one or more drugs that fall into one of five categories.

Diuretics

Diuretics promote sodium depletion, which decreases extracellular fluid volume. It is the first-line drug for treating mild hypertension. Hydrochlorothiazide

(HydroDIURIL), a thiazide, is the most frequently prescribed diuretic to control mild hypertension.

Thiazides are not used in patients who have renal insufficiency. Loop diuretics, such as furosemide (Lasix), are usually recommended for these patients because they do not depress renal flow.

Diuretics are not used if hypertension is the result of renal-angiotensin-aldosterone involvement because these drugs tend to elevate the serum renin level. Hydrochlorothiazides are combined with beta blockers, and angiotensin-converting enzyme (ACE) inhibitors. ACE inhibitors tend to increase serum potassium (K) levels. When they are combined with the thiazide diuretic, serum potassium loss is minimized.

Sympathetic depressants (sympatholytics)

Sympatholytics (see Chapter 15) are divided into five groups. These are

• Beta-adrenergic blockers: (acebutolol HCL (Sectral), atenolol (Tenormin), metoprolol (Lopressor), Nadolol (Corgard), propranolol (Inderal).

• Centrally acting sympatholytics (adrenergic blockers): clonidine HCl (Catapres) methyldopa (Aldomet).

• Alpha-adrenergic blockers: phentolamine (Regitine); doxazosin mesylate (Cardura), terazosin HCl (Hytrin).

• Adrenergic neuron blockers (peripherally acting sympatholytics): guanethi-dine monosulfate (Ismelin), resperine (Serpasil).

• Alpha- and beta-adrenergic blockers: carteolol HCl (Cartrol, Ocupress).

Direct-acting arteriolar vasodilators

Direct-acting arteriolar vasodilators are Step 3 drugs that act by relaxing the smooth muscles of the blood vessels—mainly the arteries—causing vasodilation. Direct-acting arteriolar vasodilators promote an increase in blood flow to the brain and kidneys. Diuretics can be given with direct-acting vasodilators to decrease edema. Reflex tachycardia is caused by vasodilation and the decrease in blood pressure. Beta blockers are frequently prescribed with arteriolar vasodilators to decrease the heart rate, counteracting the effect of reflex tachycardia. Nitroprusside and diazoxide are prescribed for acute hypertensive emergencies.

A list of drugs utilized in the treatment of hypertension is provided in the Appendix. Detailed tables show doses, recommendations, expectations, side effects, contraindications, and more; available on the book's Web site (see URL in Appendix).

Angiotensin antagonists

Drugs in this group inhibit angiotensin-converting enzyme (ACE) which, in turn, inhibits the formation of angiotensin II (vasoconstrictor) and blocks the release of aldosterone. When aldosterone is blocked, peripheral resistance is lowered.

Calcium channel blockers

These drugs dilate coronary arteries and arterioles and decrease total peripheral vascular resistance by vasodilation.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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