7-9. BETA ADRENERGIC BLOCKERS
As you remember, beta adrenergic blocking agents block the effect of the
sympathetic neurotransmitters by competing for receptors.
a. Propranolol (Inderal). Propranolol is a drug used in the treatment of
hypertension, angina pectoris, and cardiac arrhythmias. Side effects associated with
propranolol include dizziness, mental confusion, and mental depression. It may also
exacerbate congestive heart failure and mask the symptoms of hypoglycemia.
b. Metoprolol (Lopressor, Toprol XL). Metoprolol is prescribed for the same
conditions as propranolol and is also indicated used in the treatment of myocardial
infarction and treatment of congestive heart failure. Normal doses for hypertension are
25 100 mg twice daily. The dose for heart failure is 6.25 12.5 mg twice daily and
adjusted upward as tolerated by the patient. This agent is available as an oral and
c. Other Beta Adrenergic Blockers. Other beta blockers used in the treatment
of hypertension include betaxolol (Kerlone), bisoprolol (Zebeta), labetolol (Trandate,
Normodyne), nadolol (Corgard), and carvedilol (Coreg). Carvedilol is also indicated
for congestive heart failure.
7-10. SMOOTH MUSCLE RELAXANTS
Drugs in this category treat hypertension by acting directly on vascular smooth
muscle by relaxing the blood vessels. Consequently, they cause vasodilation and a
decrease in peripheral resistance results in a lower blood pressure.
a. Hydralazine (Apresoline). Hydralazine is given orally or injected in the
management of hypertension. Preferably, it is used in conjunction with other
antihypertensive agents. Side effects associated with this agent include chest pain
(angina pectoris), a general feeling of weakness, unexplained sore throat, joint pain,
and headache. The patient should to be told to avoid getting up suddenly from a lying
or a sitting position.
b. Alpha adrenergic blockers. Alpha adrenergic blockers block alpha
receptors in peripheral vessels, therefore causing vasodilation. Agents in the class
include prazosin (Minipress), doxazosin (Cardura), and terazosin (Hytrin).
Doxazosin and terazosin offer the advantage of once daily dosing and the added benefit
of relieving the symptoms of benign prostatic hyperplasia (enlarged prostate gland).
Dizziness, drowsiness, and headache are common side effects associated with these
agents, especially with the first dose. Patients must be counseled on these side effects
and instructed to take the first dose in the evening at home. Some patients who have
taken this drug have also experienced syncope (unconsciousness due to decreased
oxygen supply to the brain).