atenolol

Atenolol is a beta-blocker medication used to treat high blood pressure (hypertension), chest pain (angina pectoris) related to coronary artery disease, abnormally rapid heart rates (tachycardias), and to prevent migraine headaches.

Atenolol blocks the effects of adrenergic chemicals, for example, adrenaline or epinephrine, released by nerves of the sympathetic nervous system.

One of the important functions of beta-adrenergic nerves is to stimulate the heart muscle to beat more rapidly. By blocking the stimulation by 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.

• Atenolol can cause 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.
• Hypersensitivity to catecholamines has been observed during withdrawal.
• Exacerbation of angina and, in some cases, myocardial infarction (MI) may occur after abrupt discontinuance.
• When long-term beta-blocker therapy (particularly with ischemic heart disease) is discontinued, dosage should be gradually reduced over 1-2 weeks with careful monitoring.
• If angina worsens markedly or acute coronary insufficiency develops, beta-blocker administration should be promptly reinitiated, at least temporarily (in addition to other measures appropriate for unstable angina).
• Do not suddenly discontinue taking beta-blocker therapy without physician advice.
• Because coronary artery disease (CAD) is common and may be unrecognized, beta-blocker therapy must be discontinued slowly, even in patients treated only for hypertension.
• Do not take if you are allergic to atenolol or any ingredients contained in this drug.
• Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.

Contraindications

• 2°/3° heart block in patients without a pacemaker
• Cardiogenic shock
• Sinus bradycardia
• Sinus node dysfunction
• Hypersensitivity
• Uncompensated cardiac failure
• Pulmonary edema

Atenolol is generally well tolerated, and side effects are mild and transient. Its side effects include:

• abdominal cramps,
• diarrhea,
• constipation,
• fatigue,
• insomnia,
• nausea,
• depression,
• dreaming, memory loss,
• fever,
• impotence,
• lightheadedness,
• slow heart rate,
• abnormal heart rhythm,
• low blood pressure,
• numbness,
• tingling,
• cold extremities, and
• sore throat.

Other side effects of atenolol include:

• severe congestive heart failure (CHF)
• sick sinus syndrome
• catatonia
• disorientation
• mood swings
• hallucinations
• headache
• impaired performance on neuropsychiatric tests
• psychoses
• short-term memory impairment
• purple-colored spots on the skin
• rashes
• nausea
• low platelet count (thrombocytopenia)
• elevated serum hepatic enzymes and bilirubin
• impotence
• Peyronie's disease
• antinuclear antibodies (ANA)
• lupus syndrome
• visual disturbances
• dry eyes
• Raynaud phenomenon

• The dose for treating high blood pressure or angina is 25-100 mg once daily.
• Acute myocardial infarction (heart attack) is treated with two 5 mg injections administered 10 minutes apart. Ten minutes after the last injection, give 50 mg every 12 hours followed by 100 mg oral atenolol daily for 6-9 days. If atenolol injections are not appropriate, patients may be treated with 100 mg daily of oral atenolol for 7 days.

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor's recommendation.

Calcium channel blockers (CCBs) 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.

Severe interactions of atenolol include:

• There are no known severe reactions with the use of atenolol.

Atenolol has serious interactions with at least 21 different drugs.

Atenolol has moderate interactions with at least 175 different drugs.

Atenolol has mild interactions with at least 40 different drugs.

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or health care provider if you have any questions about the medication. 

• Atenolol may cause harm and affect fetal growth when given to pregnant women.
• Atenolol is excreted in breast milk and may cause adverse effects in an infant being breastfed.

What preparations of atenolol are available?

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

How should I keep atenolol stored?

Atenolol should be store at room temperature 20 C to 25 C (68 F to 77 F).