Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD

GENERIC NAME: atenolol

BRAND NAME: Tenormin

DRUG CLASS AND MECHANISM: Atenolol is a beta-adrenergic blocking agent that blocks the effects of adrenergic drugs, for example, adrenaline or epinephrine, on nerves of the sympathetic nervous system. One of the important functions of beta-adrenergic stimulation is to stimulate the heart to beat more rapidly. By blocking the stimulation of these nerves, atenolol reduces the heart rate and is useful in treating abnormally rapid heart rhythms. Atenolol also reduces the force of contraction of heart muscle and lowers blood pressure. By reducing the heart rate, the force of muscle contraction, and the blood pressure against which the heart must pump, atenolol reduces the work of heart muscle and the need of the muscle for oxygen. Since angina occurs when oxygen demand of the heart muscle exceeds the supply, atenolol is helpful in treating angina. Atenolol was approved by the FDA in August 1981.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 25, 50, 100 mg. Injection: 5 mg/10 ml

STORAGE: Store at room temperature 20°to 25°C (68° to 77°F).

PRESCRIBED FOR: Atenolol is prescribed for patients with high blood pressure (hypertension). It is also used to treat chest pain (angina pectoris) related to coronary artery disease. Atenolol also is useful in slowing and regulating certain types of abnormally rapid heart rates (tachycardias). It is also prescribed for acute myocardial infarction (heart attack). Other uses for atenolol include the prevention of migraine headaches and the treatment of certain types of tremors (familial or hereditary essential tremors).

DOSING: Atenolol should be taken before meals or at bedtime.

The dose for treating high blood pressure or angina is 50-100 mg once daily.

Acute myocardial infarction (heart attack) is treated with two 5 mg injections administered 10 minutes apart followed by treatment with 100 mg oral atenolol for 6-9 days. If atenolol injections are not advisable, patients may be treated with 100 mg daily of oral atenolol for 7 days.

DRUG INTERACTIONS: Calcium channel blockers and digoxin (Lanoxin) can cause lowering of blood pressure and heart rate to dangerous levels when administered together with atenolol. Atenolol can mask the early warning symptoms of low blood sugar (hypoglycemia), and should be used with caution in patients receiving treatment for diabetes.

PREGNANCY: Atenolol may cause harm and growth retardation in the fetus when given to pregnant women.

NURSING MOTHERS: Atenolol is excreted in breast milk and my cause adverse effects in the breastfed infant.

SIDE EFFECTS: Atenolol is generally well tolerated, and side effects are mild and transient. Rare side effects include abdominal cramps, diarrhea, constipation, fatigue, insomnia, nausea, depression, dreaming, memory loss, fever, impotence, lightheadedness, slow heart rate, low blood pressure, numbness, tingling, cold extremities, and sore throat.

Atenolol can aggravate breathing difficulties in patients with asthma, chronic bronchitis, or emphysema. In patients with existing slow heart rates (bradycardias) and heart blocks (defects in the electrical conduction of the heart), atenolol can cause dangerously slow heart rates, and even shock. Atenolol reduces the force of heart muscle contraction and can aggravate symptoms of heart failure.

In patients with coronary artery disease, abruptly stopping atenolol can suddenly worsen angina, and occasionally precipitate heart attacks. If it is necessary to discontinue atenolol, its dosage can be reduced gradually over several weeks.

From the Doctors at MedicineNet.com

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