Norepinephrine increases total peripheral resistance and mean arterial pressure.

Epinephrine predominantly affects the heart through β1 receptors, causing an increase in heart rate and cardiac output.

Isoproterenol causes a marked decrease in total peripheral resistance and an increase in heart rate and cardiac output.

α2 Agonists reduce sympathetic nerve activity and are used to treat hypertension.

Most of the α antagonists allow vasodilation and, thus, decrease blood pressure.

The side effects of the α-blockers are directly related to their α-blocking activity.

TAMSULOSIN and silodosin are specific antagonists of the α1A receptor and are used in the symptomatic treatment of benign prostatic hypertrophy.

All of the α-blockers are reversible inhibitors of the α receptor, except phenoxybenzamine, which is irreversible.

The “-azosins,” such as PRAZOSIN, are used in the treatment of hypertension.

The β-blockers have widespread use in the management of cardiac arrhythmias, angina, and hypertension.

β-Blockers should be used with caution in diabetics.

β1 Selective antagonists are often referred to as cardioselective.

The adverse effects of these drugs are, for the most part, directly related to their β-blocking abilities.

Some β-blockers are said to have intrinsic sympathomimetic activity. This means they have partial agonist activity, even though they are classified as β-blockers.

Labetalol has both α- and β-blocking activity.

The thiazide diuretics inhibit sodium and chloride reabsorption in the thick ascending loop of Henle and early distal tubule. This loss of ions increases urine volume.

The thiazide diuretics are the drugs of choice in the treatment of primary hypertension.

The thiazide diuretics can cause hypokalemia.

The loop diuretics inhibit chloride reabsorption in the thick ascending loop of Henle.

The loop diuretics are commonly used to reduce pulmonary edema in patients with congestive heart failure.