Atenolol Chlorthalidone (Tenoretic 50) Risks, Warnings, and Complications

CONGESTIVE HEART FAILURE: Beta blockers, including atenolol, can worsen the ability of the heart muscle to contract (pump blood), which can lead to more severe heart failure. Continued use of a beta-adrenergic blocking agent can lead to heart failure in people without a history of this condition. Tell your doctor right away if you develop fatigue, swelling in the hands and feet, or shortness of breath while on atenolol and chlorthalidone.

RENAL AND HEPATIC DISEASE: Atenolol is eliminated from the body by the kidneys, and this drug should be used with caution in people with impaired renal function (kidney disease). In addition, in people with kidney disease, thiazide diuretics such as chlorthalidone can cause electrolyte imbalance and precipitate azotemia (high levels of nitrogen compounds in the blood). Your doctor will keep an eye on kidney function and electrolyte levels. You may need to stop taking Tenoretic if you develop kidney problems. 

The combination of atenolol and chlorthalidone should also be used with caution in people with impaired hepatic function (liver disease). Such individuals are at risk of hepatic coma with minor changes in fluid and electrolyte balance. 

HEART DISEASE: Suddenly stopping beta-blockers in patients with coronary artery disease can lead to worsening angina pectoris (chest pain) and sometimes even myocardial infarction (heart attack). Do not stop taking atenolol and chlorthalidone without consulting your doctor. If you are coming off this medicine, your doctor will carefully observe you and ask you to limit physical activity during this time. 

USE WITH CALCIUM CHANNEL BLOCKERS: Concomitant use of beta blockers and calcium channel blockers such as verapamil and diltiazem can result in bradycardia (slowed heart rate) and second or third-degree heart block. Give your doctor and pharmacist a complete list of all your medications before starting atenolol and chlorthalidone. Also, tell your doctor if you have a history of heart disease. People with pre-existing cardiac conduction abnormalities or left ventricular dysfunction are at high risk of these complications. 

LUNG DISEASE: People with bronchospastic disease (conditions such as asthma that cause narrowing of the airways) should not receive beta-blockers in general. However, because atenolol has relative beta1-selectivity for the heart, it can be used with caution in people with bronchospastic disease if they do not tolerate other antihypertensive drugs. If you have a history of lung conditions such as asthma, COPD, or emphysema, and need to take atenolol and chlorthalidone, your doctor will prescribe the lowest possible dose of this antihypertensive combination drug.

MAJOR SURGERY: People taking beta blockers long-term usually do not usually need to stop the medication before major surgery. However, these drugs can impair the ability of the heart to respond to certain stimuli, and this can increase the risks associated with general anesthesia and surgical procedures. Tell your doctor you are on atenolol and chlorthalidone before any surgical procedure.

METABOLIC AND ENDOCRINE EFFECTS: Beta blockers, including atenolol, can mask the early warning signs of hypoglycemia (low blood sugar), such as a fast heartbeat. This can increase the risk of severe or prolonged hypoglycemia during treatment with beta-blockers. The risk is especially high in people with diabetes mellitus and those who are not eating normally or are vomiting. Talk to your doctor about how to recognize signs of severe hypoglycemia and what to do if it occurs (you need to seek emergency medical attention). People with diabetes who take insulin may need an adjustment in their insulin doses. 

Beta-adrenergic blocking drugs can also mask the symptoms of hyperthyroidism (overactive thyroid gland), such as a fast heartbeat. Suddenly stopping the use of a beta blocker can cause a thyroid storm and thyrotoxicosis. Seek emergency medical care if you develop nervousness, a rapid heart rate, unexplained weight loss, or heat intolerance.

Thiazide diuretics, including chlorthalidone, can decrease calcium excretion. Therefore, atenolol and chlorthalidone may need to be stopped before parathyroid function testing. Long-term thiazide therapy can lead to hypercalcemia (high calcium) and hypophosphatemia (low phosphate) due to changes in the parathyroid glands. Treatment with Tenoretic can also lead to hyperuricemia (increased uric acid levels), which can trigger an acute gout attack. 

People with untreated pheochromocytoma (a rare tumor of the adrenal glands) should not take atenolol and chlorthalidone.

RISKS DURING PREGNANCY AND LACTATION: Atenolol can be harmful to the unborn baby if it is taken during pregnancy. Use of this medication starting in the second trimester of pregnancy is linked to growth retardation in the baby and small-for-gestational-age infants. There aren’t enough studies to say if atenolol therapy is safe in the first trimester. Chlorthalidone has been linked to fetal or neonatal jaundice, thrombocytopenia (low platelets), and other adverse reactions.

Babies born to mothers who are on beta blocker therapy (atenolol) during childbirth and breastfeeding are at risk of bradycardia (slow heartbeat) and hypoglycemia (low blood sugar). Talk to your doctor about the benefits versus risk of taking this drug if you are nursing an infant with breast milk.

Before starting atenolol and chlorthalidone, tell your doctor if you are pregnant or might be pregnant. Call your doctor immediately if you become pregnant while on this combination drug.