Atenolol -- a heart drug

These comments are made for the purpose of discussion and should NOT be used as recommendations for or against therapies or other treatments. An individual patient is always advised to consult their own physician.

Atenolol side effects [posted 1/13/99]
Question: Could atenolol be a cause of the sensory (probably small fiber) neuropathy my neurologist thinks I have?

Atenolol side effects [posted 1/11/99]
Question: My 88-year-old aunt has recently begun taking atenolol for hypertension. She is having diarrhea to the extent that she's afraid to go out in public. How should I advise her?

Answer: Switch to another medicine. There are many other classes to pick from and beta blockers are very hard for the elderly to tolerate. If she can't switch, using fiber expanders might help.

Can Atenolol Increase My Triglyceride Count [posted 10/30/98]
Question: I am 45 years old and have been taking Atenolol for almost 1 year. Atenolol was prescribed to control a mild hypertension condition. When I first went on the drug 10 mg was prescribed. Over the past 3-4 months I have noticed additional side effects that concern me. I spoke to the Doctor about these side effects and he said Atenolol should not be the cause. He said to reduce the dose to 5mg. Even at 5 mg I feel waves of fatigue and lightheadedness. For about 2.5 hours after I take Atenolol I experience irregular heartbeat and fatigue. Occaisionally I am awaken during the night with the irregular heartbeat. I am not taking any other medication with Atenolol. I want to come off it but I am concerned how to wean myself. Is 5mg/day a small enough dose to just stop or do I need to take less and less over a two week period. Also, how long does Atenolol stay in the body after you stop taking it? Thank you in advance for your response.

Answer: 5 mg is extremely low. There should be no problem stopping it, if you do not have coronary artery disease, which you are not describing. Just stop.

Can Atenolol Increase My Triglyceride Count [posted 10/30/98]
Question: I have been taking 75 mg of Atenolol for high blood pressure. It works well. My triglyceride count is high (getting higher each year). I eat a low fat diet and my doctor is concerned. Can this medication be causing an increase in my triglycerides?

Answer: Maybe, but triglycerides are really a pretty low factor in heart disease. There is a correlation between triglyceride levels and eventual development of diabetes mellitus. Lose weight would usually fix the elevated triglycerides;but, it's a pretty small risk unless they are over 2,000 or so.

Atenolol & St. John's Wart [posted 10/30/98]
Question: I have been taking 50mg of atenolol per day for mitrol valve prolapse. I experience some side effects which especially include fatigue, slight depression or occasional anger. I am considering trying St. John's Wort to level out my emotions. I asked the pharmacy if the combination was OK - they said not to take the two together if being treated for high blood pressure. When I said I was being treated for MVP, they said it was OK then. I was concerned about this, so I called to verify this with my doctor. The doctor's office said they don't recommend taking St. John's Wort at all because it hasn't been tested enough. So, is it really OK to take the combination when being treated for MVP?

Answer: Probably no problem. St. John's Wort is thought to be a mild MAO inhibitor. There is no contraindication to this class of drugs with beta blockers. Get a list of foods from your doctor that should be avoided with MAO inhibitors. Theorectically, these can produce a hypertensive crisis if taken with MAO inhibitors. In practice, rarely seen with St. John's Wort.

Skin Rash and Atenolol [posted 8/5/98]
Question: I have been taking Tenormin for a number of years for high blood pressure. In June I switched to Atenolol because it was cheaper. Beginning in August I developed a skin rash. At times it has been so bad I have been on Prednisone twice. While I'm on Prednisone the itching is controlled. Once I go off of it, the itching starts within a week. Could there be any connection between the Atenolol and the rash?

Answer: Wouldn't think so unless there are chemicals in the generic Atenolol not in Tenormin. Try going back on brand name Tenormin for 4-5 months and see if the rash abates.

Atenolol and Phosphate Levels [posted 7/17/98]
Question: Can the usage of Atenolol lead to a lower or dangerous level of phosphates within the system?

Atenolol
Question: Is there any danger in taking 50 mg per day of atenolol if I have ocular hypertension and a reading of 21?

Atenolol
Question: My mom is 65 years old with no significant medical history. She is known to have high blood pressure from time to time. This is usually in the doctors office, but when it is checked at home, it is fine. For the past 4 years, she has been doing step aerobics for 1 hour, 3 times a week. This is not a program designed for seniors and she keeps up well with women less than half her age. She does use a low block and limits her arm movements to prevent getting her heart rate too high. Her heart rate does reach 160-170 bpm and is down to normal range within an hour. Recently her medical doctor put her on atenolol 25 mg, saying 160 bpm is too high. Now her heart rate gets up to 130, but she doesn't feel as good. Is there significant benefit in putting Mom on a beta blocker.

Answer: Probably not, but it would depend on her overall cardiac condition. This can be assessed by a stress echo. But, I'd let her go if she was my patient, assuming no history of coronary disease and normal ejection fraction.

Atenolol
Question: I am taking a generic brand (by Geneva Generics) of Atenolol. My most recent prescription looks different from the original. Tablets are white, round, and marked GGl7. Others were fatter and smaller white pills. Checked w/ pharmacy, they say okay. Nervous about taking.

Answer: I wouldn't be concerned. Beta-blockers are easy to synthesize and fairly cheap as a consequence. Generics are common, and I haven't seen any difference in my practice.

Atenolol and St. John’s Wort
Question: I am currently taking 100 mg of atenolol per day for hypertension. I have been slightly depressed and had a low energy level. I have been prescribed a blend that includes St. johns wort. I have read that it is a MAO inhibitor. Can I take that with Atenolol ?

Answer: St. Johns Wort has only recently been studied in any depth. It appears to have less side effects while addressing depression. There would be no obvious interaction to date with atenolol. However, beta blockers are generally to be avoided in depression due to their ability to produce depression in susceptible patients.

Atenolol
Question: I was diagnosed with Mitral Valve Prolapse about 10 years ago. When I visited my new family doctor and told him that I was taking Atenolol/Tenormin for the condition, he seemed genuinely surprised. Should I be taking an alternative prescription for MVP? Is atenolol the best way to go?

Answer: Treatment for Mitral Valve Prolapse is aimed at symptoms generally. Occasionally, a patient has such severe tacharthymias(fast heart beats) that treatment is necessary. However, generally, it is done to address the symptoms of MVP rather than change the course of the problem. If you have documented rapid beats(in excess of 130 for greater than 10 seconds or so), or if you have passed out etc. with rapid heart beats, the medication is necessary and must be continued. However, if it is merely for the sensation of extra beats or occasional fast beats, it is merely for symptom control. Atenolol is a semi-selective beta-blocker and is the class of drugs generally used with MVP. Occasionally, calcium channel blockers are used if the person cannot tolerate beta-blockers.

Atenolol
Question: I take 100 mg of Atenolol per day for Wolfe Parkinson White Syndrome. I am having difficulty losing weight even though I exercise regularly with weight training and aerobics. Could the Atenolol be contributing to this difficulty, and how can I overcome it? I have gained approximately 25 lbs. since I started using it about 5 years ago.

Answer: While it is possible, I haven’t really seen patients complain of weight gain with beta blockers. Fatigue is common-- possibly you’re less active with beta blockers.

Atenolol and Zestril
Question: Could you please give me some information on the drugs Atenolol and Zestril? I need to know what they are used for and the side effects of each. Also, can they be used together?

Answer: Atenolol is a selective beta-blocker. Beta Blockers are common drugs used to treat many different problems. They are very effective in treating hypertension, angina, rapid heart beats, and have been used to treat stage fright and occasionally anxiety. They also have similar side effects. Beta Blockers come as selective and non-selective. The non-selective beta-blockers can cause some bronchospasm and asthma. The selective blockers can also, but much less frequently. Common side effects to both selective and non-selective beta blockers are fatigue, slow heart rate, nausea, nightmares and difficulty sleeping, impairment of insulin release, depression, and occasional skin rash. These drugs should never be stopped abruptly and require a tapering if discontinued. Zestril is a "Ace inhibitor". This is a class of drugs which block the conversion of renin to angiotensin by blocking the enzyme in the lung responsible for this conversion. Hence, angiotensin converting enzyme inhibitors (ACE). This class of drugs has remarkably few side effects except for cough. Occasional people develop a rash or other problems, but most don't know they are taking it. Beta-blockers and ACE inhibitors are used together commonly since they act in different manners in treating hypertension.

Atenolol
Question: My father has been on atenolol for many years. My mother says he is currently taking 50 mg daily. Dad shows many signs of depression and anger, and we are searching for a link as to why he is experiencing this. Could atenolol (tenormin) be the cause?

Answer: Beta Blockers are common drugs used to treat many different problems. They are very effective in treating hypertension, angina, rapid heart beats, and have been used to treat stage fright and occasionally anxiety. They also have similar side effects. Beta Blockers come as selective and non-selective. The non-selective beta blockers can cause some bronchospasm and asthma. The selective blockers can also but much less frequently. Common side effects to both selective and non-selective beta blockers are: fatigue, slow heart rate, nausea, nightmares and difficulty sleeping, impairment of insulin release, depression, and occasional skin rash. These drugs should never be stopped abruptly and require a tapering if discontinued.

Question: I have recently started taking atenolol again for tachycardia and resultant drops in blood pressure. Seven months ago I had an ablation for WPW. I am experiencing extreme fatigue, and exceptionally vivid dreams which seem to be interfering with my sleep cycle. Is there something similar to atenolol which wouldn't have these side effects?

Answer: Beta Blockers are common drugs used to treat many different problems They are very effective in treating hypertension, angina, rapid heart beats, and have been used to treat stage fright and occasionally anxiety. They also have similar side effects. Beta Blockers come as selective and non-selective. The non-selective beta blockers can cause some bronchospasm and asthma. The selective blockers can also but much less frequently. Common side effects to both selective and non-selective beta blockers are: fatigue, slow heart rate, nausea, nightmares and difficulty sleeping, impairment of insulin release, depression, and occasional skin rash. These drugs should never be stopped abruptly and require a tapering if discontinued. Calcium channel blockers can often slow the heart without these side effects. Drugs like verapamil are used commonly to treat rapid heart rhythms.

Question: I have conflicting information on whether desoxyn (methamphetamine) and/or atenolol (tenormin) may contribute to glucose elevation in the blood. I take 60mg of desoxyn and 25mg of atenolol daily. I have narcolepsy, but I have recently experienced elevated blood sugar. Decreasing the level of Desoxyn seems to lower the blood sugar level to normal levels. Could my observation be valid, or is there no connection between the medication and the diabetic condition?

Answer: Atenolol is included in a class of drugs called beta-blockers. Beta-blockers do have the potential ability to increase glucose by inhibiting the release of insulin. Other potential problems with diabetics include masking of low sugar symptoms and blunting of the return of glucose after an excessively low sugar. Some beta-blockers like atenolol are selective beta-blockers and have less of these effects, particularly in doses under 100mg. In practice, 25mg of atenolol would not be expected to have too many effects on a diabetic. Methamphetamine has no such direct effect on insulin. Indirectly, they may affect the patient’s weight and their insulin requirements.

Hair Loss
Question: My girlfriend's daughter recently started taking Atenolol due to an enlarged aeorta. Within the past two weeks she has suddenly started experiencing RAPID hair loss. Her doctor says that it cannot possibly be caused by the Atenolol, but my girlfriend and I can come up with no other explanation. Is it possible that the Atenolol could be causing this hair loss? Thank-you.

Answer: Atenolol belongs to a class of drugs called beta-blockers. These drugs block the beta receptors in the body. As a consequence, they are used in treating high blood pressure, hypertension, anxiety disorders, rapid heart beat syndromes and a host of other problems. The most common side effects of the beta-blockers are slow heart rates, fatigue, and occasional dyspnea. Hair loss is also seen in about 1-5% of patients.

"Heart Dropping"
Question: I am a 26 year old female who has a 10 yr history of PSVT. Recently I was prescribed Atenolol 50 mg. I have only been taking it for a week, but I keep having the sensation of my heart "dropping" as if I were in an elevator at least 10 x day. Is this a side effect of the drug? Would a lower dosage help stop this?

Answer: I suspect you are having PACs due to the bradycardia induced by the atenolol. This occurs when the puylse becomes slow and an extra beat is initiated by the heart. The subsequent beat after the PAC has additional time to fill and generates an extra large discharge of blood. The "drop" sensation comes from the beat after the extra beat. However, the extra beat is induced by slowness caused by atenolol. Have you tried to decrease your dosage to 25 or 12.5 mg to see if it decreases the PSVT and eliminates this problem?

Neuro-Cardiogenic Syncope
Question: My husband, 40 years old, was recently diagnosed with neuro-cardiogenic syncope and prescribed 10mg of Atenolol per day. I understand this is a very low dosage, however I'm concerned about his change in behavior/personality. He's now very quick to anger, seems irritable even though he says he feels fine. He doesn't show any signs of depression and his blood pressure is 120/80. I haven't noticed any signs of impotency (no problems there) or hair loss. I have noticed that he's tired, his face is red and puffy. He weighs approx. 210. We're tired of walking on eggshells.

Answer: Yes, change the medication to something else-not a beta blocker, this is unacceptable.

TENORETIC^® (atenolol and chlorthalidone) is for the treatment of hypertension. It combines the antihypertensive activity of two agents: a beta₁-selective (cardioselective) hydrophilic blocking agent (atenolol, TENORMIN(r)) and a monosulfonamyl diuretic (chlorthalidone). Atenolol is Benzeneacetamide, 4-[2'-hydroxy-3'-[(1-methylethyl) amino] propoxy]-.

Atenolol (free base) is a relatively polar hydrophilic compound with a water solubility of 26.5 mg/mL at 37°C. It is freely soluble in 1N HCl (300 mg/mL at 25°C) and less soluble in chloroform (3 mg/mL at 25°C).

Chlorthalidone is 2-Chloro-5-(1-hydroxy-3-oxo-1-isoindolinyl) benzene sulfonamide: Chemical Symbol 2

Chlorthalidone has a water solubility of 12 mg/100 mL at 20°C.

  Each TENORETIC 100 Tablet contains:
  Atenolol (TENORMIN(r)).....................................................100 mg
  Chlorthalidone......................................................................25 mg

Atenolol (TENORMIN(r))......................................................50 mg
Chlorthalidone......................................................................25 mg

Inactive ingredients: magnesium stearate, microcrystalline cellulose, povidone, sodium starch glycolate.

Atenolol and chlorthalidone have been used singly and concomitantly for the treatment of hypertension. The antihypertensive effects of these agents are additive, and studies have shown that there is no interference with bioavailability when these agents are given together in the single combination tablet. Therefore, this combination provides a convenient formulation for the concomitant administration of these two entities. In patients with more severe hypertension, TENORETIC may be administered with other antihypertensives such as vasodilators.

Atenolol is a beta₁-selective (cardioselective) beta-adrenergic receptor blocking agent without membrane stabilizing or intrinsic sympathomimetic (partial agonist) activities. This preferential effect is not absolute, however, and at higher doses, atenolol inhibits beta₂-adrenoreceptors, chiefly located in the bronchial and vascular musculature.

Pharmacodynamics: In standard animal or human pharmacological tests, beta-adrenoreceptor blocking activity of atenolol has been demonstrated by: (1) reduction in resting and exercise heart rates and cardiac output, (2) reduction of systolic and diastolic blood pressure at rest and on exercise, (3) inhibition of isoproterenol induced tachycardia, and (4) reduction in reflex orthostatic tachycardia.

A significant beta-blocking effect of atenolol, as measured by reduction of exercise tachycardia, is apparent within one hour following oral administration of a single dose. This effect is maximal at about 2 to 4 hours and persists for at least 24 hours. The effect at 24 hours is dose related and also bears a linear relationship to the logarithm of plasma atenolol concentration. However, as has been shown for all beta blocking agents, the antihypertensive effect does not appear to be related to plasma level.

In normal subjects, the beta₁-selectivity of atenolol has been shown by its reduced ability to reverse the beta₂-mediated vasodilating effect of isoproterenol as compared to equivalent beta-blocking doses of propranolol. In asthmatic patients, a dose of atenolol producing a greater effect on resting heart rate than propranolol resulted in much less increase in airway resistance. In a placebo controlled comparison of approximately equipotent oral doses of several beta-blockers, atenolol produced a significantly smaller decrease of FEV₁ than nonselective beta-blockers, such as propranolol and unlike those agents did not inhibit bronchodilation in response to isoproterenol.

Consistent with its negative chronotropic effect due to beta blockade of the SA node, atenolol increases sinus cycle length and sinus node recovery time. Conduction in the AV node is also prolonged. Atenolol is devoid of membrane stabilizing activity, and increasing the dose well beyond that producing beta blockade does not further depress myocardial contractility. Several studies have demonstrated a moderate (approximately 10%) increase in stroke volume at rest and exercise.

In controlled clinical trials, atenolol given as a single daily dose, was an effective antihypertensive agent providing 24-hour reduction of blood pressure. Atenolol has been studied in combination with thiazide-type diuretics, and the blood pressure effects of the combination are approximately additive. Atenolol is also compatible with methyldopa, hydralazine, and prazosin, the combination resulting in a larger fall in blood pressure than with the single agents. The dose range of atenolol is narrow, and increasing the dose beyond 100 mg once daily is not associated with increased antihypertensive effect. The mechanisms of the antihypertensive effects of beta-blocking agents have not been established. Several mechanisms have been proposed and include: (1) competitive antagonism of catecholamines at peripheral (especially cardiac) adrenergic neuron sites, leading to decreased cardiac output, (2) a central effect leading to reduced sympathetic outflow to the periphery, and (3) suppression of renin activity. The results from long-term studies have not shown any diminution of the antihypertensive efficacy of atenolol with prolonged use.

Pharmacokinetics and Metabolism: In man, absorption of an oral dose is rapid and consistent but incomplete. Approximately 50% of an oral dose is absorbed from the gastrointestinal tract, the remainder being excreted unchanged in the feces. Peak blood levels are reached between 2 and 4 hours after ingestion. Unlike propranolol or metoprolol, but like nadolol, hydrophilic atenolol undergoes little or no metabolism by the liver, and the absorbed portion is eliminated primarily by renal excretion. Atenolol also differs from propranolol in that only a small amount (6%-16%) is bound to proteins in the plasma. This kinetic profile results in relatively consistent plasma drug levels with about a fourfold interpatient variation. There is no information as to the pharmacokinetic effect of atenolol on chlorthalidone.

The elimination half-life of atenolol is approximately 6 to 7 hours, and there is no alteration of the kinetic profile of the drug by chronic administration. Following doses of 50 mg or 100 mg, both beta-blocking and antihypertensive effects persist for at least 24 hours. When renal function is impaired, elimination of atenolol is closely related to the glomerular filtration rate; but significant accumulation does not occur until the creatinine clearance falls below 35 mL/min/1.73m² (see circular for atenolol [TENORMIN(r)]).

Chlorthalidone is a monosulfonamyl diuretic which differs chemically from thiazide diuretics in that a double ring system is incorporated in its structure. It is an oral diuretic with prolonged action and low toxicity. The diuretic effect of the drug occurs within 2 hours of an oral dose. It produces diuresis with greatly increased excretion of sodium and chloride. At maximal therapeutic dosage, chlorthalidone is approximately equal in its diuretic effect to comparable maximal therapeutic doses of benzothiadiazine diuretics. The site of action appears to be the cortical diluting segment of the ascending limb of Henle's loop of the nephron.

TENORETIC is indicated in the treatment of hypertension. This fixed dose combination drug is not indicated for initial therapy of hypertension. If the fixed dose combination represents the dose appropriate to the individual patient's needs, it may be more convenient than the separate components.

TENORETIC is contraindicated in patients with: sinus bradycardia; heart block greater than first degree; cardiogenic shock; overt cardiac failure (see WARNINGS); anuria; hypersensitivity to this product or to sulfonamide-derived drugs.

Cardiac Failure: Sympathetic stimulation is necessary in supporting circulatory function in congestive heart failure, and beta blockade carries the potential hazard of further depressing myocardial contractility and precipitating more severe failure. In patients who have congestive heart failure controlled by digitalis and/or diuretics, TENORETIC should be administered cautiously. Both digitalis and atenolol slow AV conduction.

IN PATIENTS WITHOUT A HISTORY OF CARDIAC FAILURE, continued depression of the myocardium with beta-blocking agents over a period of time can, in some cases, lead to cardiac failure. At the first sign or symptom of impending cardiac failure, patients receiving TENORETIC should be digitalized and/or be given additional diuretic therapy. Observe the patient closely. If cardiac failure continues despite adequate digitalization and diuretic therapy, TENORETIC therapy should be withdrawn.

Renal and Hepatic Disease and Electrolyte Disturbances: Since atenolol is excreted via the kidneys, TENORETIC should be used with caution in patients with impaired renal function.

In patients with renal disease, thiazides may precipitate azotemia. Since cumulative effects may develop in the presence of impaired renal function, if progressive renal impairment becomes evident, TENORETIC should be discontinued.

In patients with impaired hepatic function or progressive liver disease, minor alterations in fluid and electrolyte balance may precipitate hepatic coma. TENORETIC should be used with caution in these patients.

Ischemic Heart Disease: Following abrupt cessation of therapy with certain beta-blocking agents in patients with coronary artery disease, exacerbations of angina pectoris and, in some cases, myocardial infarction have been reported. Therefore, such patients should be cautioned against interruption of therapy without the physician's advice. Even in the absence of overt angina pectoris, when discontinuation of TENORETIC is planned, the patient should be carefully observed and should be advised to limit physical activity to a minimum. TENORETIC should be reinstated if withdrawal symptoms occur. Because coronary artery disease is common and may be unrecognized, it may be prudent not to discontinue TENORETIC therapy abruptly even in patients treated only for hypertension.

Concomitant Use of Calcium Channel Blockers: Bradycardia and heart block can occur, and the left ventricular end diastolic pressure can rise when beta blockers are administered with verapamil or diltiazem. Patients with pre-existing conduction abnormalities or left ventricular dysfunction are particularly susceptible. (See PRECAUTIONS.)

Bronchospastic Diseases: PATIENTS WITH BRONCHOSPASTIC DISEASE SHOULD, IN GENERAL, NOT RECEIVE BETA-BLOCKERS. Because of its relative beta₁-selectivity, however, TENORETIC may be used with caution in patients with bronchospastic disease who do not respond to or cannot tolerate, other antihypertensive treatment. Since beta₁-selectivity is not absolute, the lowest possible dose of TENORETIC should be used, and a beta₂-stimulating agent (bronchodilator) should be made available. If dosage must be increased, dividing the dose should be considered in order to achieve lower peak blood levels.

Anesthesia and Major Surgery: It is not advisable to withdraw beta-adrenoreceptor blocking drugs prior to surgery in the majority of patients. However, care should be taken when using anesthetic agents such as those which may depress the myocardium. Vagal dominance, if it occurs, may be corrected with atropine (1-2 mg IV).

Beta-blockers are competitive inhibitors of beta-receptor agonists, and their effects on the heart can be reversed by administration of such agents; eg, dobutamine or isoproterenol with caution (see section on Overdosage).

Metabolic and Endocrine Effects: TENORETIC may be used with caution in diabetic patients. Beta-blockers may mask tachycardia occurring with hypoglycemia, but other manifestations such as dizziness and sweating may not be significantly affected. At recommended doses atenolol does not potentiate insulin-induced hypoglycemia and, unlike nonselective beta-blockers, does not delay recovery of blood glucose to normal levels.

Insulin requirements in diabetic patients may be increased, decreased or unchanged; latent diabetes mellitus may become manifest during chlorthalidone administration.

Beta-adrenergic blockade may mask certain clinical signs (eg, tachycardia) of hyperthyroidism. Abrupt withdrawal of beta blockade might precipitate a thyroid storm; therefore, patients suspected of developing thyrotoxicosis from whom TENORETIC therapy is to be withdrawn should be monitored closely.

Because calcium excretion is decreased by thiazides, TENORETIC should be discontinued before carrying out tests for parathyroid function. Pathologic changes in the parathyroid glands, with hypercalcemia and hypophosphatemia, have been observed in a few patients on prolonged thiazide therapy; however, the common complications of hyperparathyroidism such as renal lithiasis, bone resorption, and peptic ulceration have not been seen.

Hyperuricemia may occur, or acute gout may be precipitated in certain patients receiving thiazide therapy.

Pregnancy and Fetal Injury: Atenolol can cause fetal harm when administered to a pregnant woman. Atenolol crosses the placental barrier and appears in cord blood. Administration of atenolol, starting in the second trimester of pregnancy, has been associated with the birth of infants that are small for gestational age. No studies have been performed on the use of atenolol in the first trimester, and the possibility of fetal injury cannot be excluded. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.

TENORETIC was studied for teratogenic potential in the rat and rabbit. Doses of atenolol/chlorthalidone of 8/2, 80/20, and 240/60 mg/kg/day were administered orally to pregnant rats with no evidence of embryofetotoxicity observed. Two studies were conducted in rabbits. In the first study, pregnant rabbits were dosed with 8/2, 80/20, and 160/40 mg/kg/day of atenolol/chlorthalidone. No teratogenic effects were noted, but embryonic resorptions were observed at all dose levels (ranging from approximately 5 times to 100 times the maximum recommended human dose*). In the second rabbit study, doses of atenolol/chlorthalidone were 4/1, 8/2, and 20/5 mg/kg/day. No teratogenic or embryotoxic effects were demonstrated.

Atenolol - Atenolol has been shown to produce a dose-related increase in embryo/fetal resorptions in rats at doses equal to or greater than 50 mg/kg/day or 25 or more times the maximum recommended human antihypertensive dose.* Although similar effects were not seen in rabbits, the compound was not evaluated in rabbits at doses above 25 mg/kg/day or 12.5 times the maximum recommended human antihypertensive dose.*
*Based on the maximum dose of 100 mg/day in a 50 kg patient.

Chlorthalidone - Thiazides cross the placental barrier and appear in cord blood. The use of chlorthalidone and related drugs in pregnant women requires that the anticipated benefits of the drug be weighed against possible hazards to the fetus. These hazards include fetal or neonatal jaundice, thrombocytopenia, and possibly other adverse reactions which have occurred in the adult.

Electrolyte and Fluid Balance Status: Periodic determination of serum electrolytes to detect possible electrolyte imbalance should be performed at appropriate intervals.

Patients should be observed for clinical signs of fluid or electrolyte imbalance; ie, hyponatremia, hypochloremic alkalosis, and hypokalemia. Serum and urine electrolyte determinations are particularly important when the patient is vomiting excessively or receiving parenteral fluids. Warning signs or symptoms of fluid and electrolyte imbalance include dryness of the mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, and gastrointestinal disturbances such as nausea and vomiting.

Measurement of potassium levels is appropriate especially in elderly patients, those receiving digitalis preparations for cardiac failure, patients whose dietary intake of potassium is abnormally low, or those suffering from gastrointestinal complaints.

Hypokalemia may develop especially with brisk diuresis, when severe cirrhosis is present, or during concomitant use of corticosteroids or ACTH.

Interference with adequate oral electrolyte intake will also contribute to hypokalemia. Hypokalemia can sensitize or exaggerate the response of the heart to the toxic effects of digitalis (eg, increased ventricular irritability). Hypokalemia may be avoided or treated by use of potassium supplements or foods with a high potassium content.

Any chloride deficit during thiazide therapy is generally mild and usually does not require specific treatment except under extraordinary circumstances (as in liver disease or renal disease). Dilutional hyponatremia may occur in edematous patients in hot weather; appropriate therapy is water restriction rather than administration of salt except in rare instances when the hyponatremia is life-threatening. In actual salt depletion, appropriate replacement is the therapy of choice.

Drug Interactions: TENORETIC may potentiate the action of other antihypertensive agents used concomitantly. Patients treated with TENORETIC plus a catecholamine depletor (eg, reserpine) should be closely observed for evidence of hypotension and/or marked bradycardia which may produce vertigo, syncope, or postural hypotension.

Calcium channel blockers may also have an additive effect when given with TENORETIC (See WARNINGS).

Thiazides may decrease arterial responsiveness to norepinephrine. This diminution is not sufficient to preclude the therapeutic effectiveness of norepinephrine. Thiazides may increase the responsiveness to tubocurarine.

Lithium generally should not be given with diuretics because they reduce its renal clearance and add a high risk of lithium toxicity. Read circulars for lithium preparations before use of such preparations with TENORETIC.

Beta blockers may exacerbate the rebound hypertension which can follow the withdrawal of clonidine. If the two drugs are coadministered, the beta-blocker should be withdrawn several days before the gradual withdrawal of clonidine. If replacing clonidine by beta-blocker therapy, the introduction of beta-blockers should be delayed for several days after clonidine administration has stopped.

While taking beta blockers, patients with a history of anaphylactic reaction to a variety of allergens may have a more severe reaction on repeated challenge, either accidental, diagnostic, or therapeutic. Such patients may be unresponsive to the usual doses of epinephrine used to treat the allergic reaction.

Other Precautions: In patients receiving thiazides, sensitivity reactions may occur with or without a history of allergy or bronchial asthma. The possible exacerbation or activation of systemic lupus erythematosus has been reported. The antihypertensive effects of thiazides may be enhanced in the postsympathectomy patient.

Carcinogenesis, Mutagenesis, Impairment of Fertility: Two long-term (maximum dosing duration of 18 or 24 months) rat studies and one long-term (maximum dosing duration of 18 months) mouse study, each employing dose levels as high as 300 mg/kg/day or 150 times the maximum recommended human antihypertensive dose,* did not indicate a carcinogenic potential of atenolol. A third (24-month) rat study, employing doses of 500 and 1,500 mg/kg/day (250 and 750 times the maximum recommended human antihypertensive dose*) resulted in increased incidences of benign adrenal medullary tumors in males and females, mammary fibroadenomas in females, and anterior pituitary adenomas and thyroid parafollicular cell carcinomas in males. No evidence of a mutagenic potential of atenolol was uncovered in the dominant lethal test (mouse), in vivo cytogenetics test (Chinese hamster) or Ames test (S. typhimurium).

Fertility of male or female rats (evaluated at dose levels as high as 200 mg/kg/day or 100 times the maximum recommended human dose*) was unaffected by atenolol administration.

Animal Toxicology: Six-month oral administration studies were conducted in rats and dogs using TENORETIC doses up to 12.5 mg/kg/day (atenolol/chlorthalidone 10/2.5 mg/kg/day – approximately five times the maximum recommended human antihypertensive dose*). There were no functional or morphological abnormalities resulting from dosing, either compound alone or together, other than minor changes in heart rate, blood pressure, and urine chemistry which were attributed to the known pharmacologic properties of atenolol and/or chlorthalidone.

Chronic studies of atenolol performed in animals have revealed the occurrence of vacuolation of epithelial cells of Brunner's glands in the duodenum of both male and female dogs at all tested dose levels (starting at 15 mg/kg/day or 7.5 times the maximum recommended human antihypertensive dose*) and increased incidence of atrial degeneration of hearts of male rats at 300 but not 150 mg atenolol/kg/day (150 and 75 times the maximum recommended human antihypertensive dose*, respectively).
*Based on the maximum dose of 100 mg/day in a 50 kg patient.

Use in Pregnancy: Pregnancy Category D: See WARNINGS - Pregnancy and Fetal Injury.

Nursing Mothers: Atenolol is excreted in human breast milk at a ratio of 1.5 to 6.8 when compared to the concentration in plasma. Caution should be exercised when atenolol is administered to a nursing woman. Clinically significant bradycardia has been reported in breast fed infants. Premature infants, or infants with impaired renal function, may be more likely to develop adverse effects.

Pediatric Use: Safety and effectiveness in pediatric patients have not been established.

TENORETIC is usually well tolerated in properly selected patients. Most adverse effects have been mild and transient. The adverse effects observed for TENORETIC are essentially the same as those seen with the individual components.

Atenolol: The frequency estimates in the following table were derived from controlled studies in which adverse reactions were either volunteered by the patient (US studies) or elicited, eg, by checklist (foreign studies). The reported frequency of elicited adverse effects was higher for both atenolol and placebo-treated patients than when these reactions were volunteered. Where frequency of adverse effects for atenolol and placebo is similar, causal relationship to atenolol is uncertain.

During postmarketing experience, the following have been reported in temporal relationship to the use of the drug: elevated liver enzymes and/or bilirubin, hallucinations, headache, impotence, Peyronie's disease, postural hypotension which may be associated with syncope, psoriasiform rash or exacerbation of psoriasis, psychoses, purpura, reversible alopecia, thrombocytopenia, and visual disturbances. TENORETIC, like other beta-blockers, has been associated with the development of antinuclear antibodies (ANA) and lupus syndrome.

Chlorthalidone: Cardiovascular: orthostatic hypotension; Gastrointestinal: anorexia, gastric irritation, vomiting, cramping, constipation, jaundice (intrahepatic cholestatic jaundice), pancreatitis; CNS: vertigo, paresthesia, xanthopsia; Hematologic: leukopenia, agranulocytosis, thrombocytopenia, aplastic anemia; Hypersensitivity: purpura, photosensitivity, rash, urticaria, necrotizing angiitis (vasculitis) (cutaneous vasculitis), Lyell's syndrome (toxic epidermal necrolysis); Miscellaneous: hyperglycemia, glycosuria, hyperuricemia, muscle spasm, weakness, restlessness. Clinical trials of TENORETIC conducted in the United States (89 patients treated with TENORETIC) revealed no new or unexpected adverse effects.

POTENTIAL ADVERSE EFFECTS: In addition, a variety of adverse effects not observed in clinical trials with atenolol but reported with other beta-adrenergic blocking agents should be considered potential adverse effects of atenolol. Nervous System: Reversible mental depression progressing to catatonia; an acute reversible syndrome characterized by disorientation for time and place, short-term memory loss, emotional lability, slightly clouded sensorium, decreased performance on neuropsychometrics; Cardiovascular: Intensification of AV block (see CONTRAINDICATIONS); Gastrointestinal: Mesenteric arterial thrombosis, ischemic colitis; Hematologic: Agranulocytosis; Allergic: Erythematous rash, fever combined with aching and sore throat, laryngospasm, and respiratory distress; Other: Raynaud's phenomenon.

Miscellaneous: There have been reports of skin rashes and/or dry eyes associated with the use of beta-adrenergic blocking drugs. The reported incidence is small, and, in most cases, the symptoms have cleared when treatment was withdrawn. Discontinuance of the drug should be considered if any such reaction is not otherwise explicable. Patients should be closely monitored following cessation of therapy. (See DOSAGE AND ADMINISTRATION.)

The oculomucocutaneous syndrome associated with the beta-blocker practolol has not been reported with atenolol (TENORMIN). Furthermore, a number of patients who had previously demonstrated established practolol reactions were transferred to atenolol (TENORMIN) therapy with subsequent resolution or quiescence of the reaction.

Clinical Laboratory Test Findings: Clinically important changes in standard laboratory parameters were rarely associated with the administration of TENORETIC. The changes in laboratory parameters were not progressive and usually were not associated with clinical manifestations. The most common changes were increases in uric acid and decreases in serum potassium.

No specific information is available with regard to overdosage and TENORETIC in humans. Treatment should be symptomatic and supportive and directed to the removal of any unabsorbed drug by induced emesis or administration of activated charcoal. Atenolol can be removed from the general circulation by hemodialysis. Further consideration should be given to dehydration, electrolyte imbalance, and hypotension by established procedures.

Atenolol: Overdosage with atenolol has been reported with patients surviving acute doses as high as 5 g. One death was reported in a man who may have taken as much as 10 g acutely.

The predominant symptoms reported following atenolol overdose are lethargy, disorder of respiratory drive, wheezing, sinus pause, and bradycardia. Additionally, common effects associated with overdosage of any beta-adrenergic blocking agent are congestive heart failure, hypotension, bronchospasm, and/or hypoglycemia. Other treatment modalities should be employed at the physician's discretion and may include:

BRADYCARDIA: Atropine 1-2 mg intravenously. If there is no response to vagal blockade, give isoproterenol cautiously. In refractory cases, a transvenous cardiac pacemaker may be indicated. Glucagon in a 10 mg intravenous bolus has been reported to be useful. If required, this may be repeated or followed by an intravenous infusion of glucagon 1-10 mg/h depending on response.

CONGESTIVE HEART FAILURE: Digitalize the patient and administer a diuretic. Glucagon has been reported to be useful.

HYPOTENSION: Vasopressors such as dopamine or norepinephrine (levarterenol). Monitor blood pressure continuously.

BRONCHOSPASM: A beta₂-stimulant such as isoproterenol or terbutaline and/or aminophylline.

ELECTROLYTE DISTURBANCE: Monitor electrolyte levels and renal function. Institute measures to maintain hydration and electrolytes.

Based on the severity of symptoms, management may require intensive support care and facilities for applying cardiac and respiratory support.

Chlorthalidone: Symptoms of chlorthalidone overdose include nausea, weakness, dizziness, and disturbances of electrolyte balance.

Chlorthalidone is usually given at a dose of 25 mg daily; the usual initial dose of atenolol is 50 mg daily. Therefore, the initial dose should be one TENORETIC 50 tablet given once a day. If an optimal response is not achieved, the dosage should be increased to one TENORETIC 100 tablet given once a day.

When necessary, another antihypertensive agent may be added gradually beginning with 50 percent of the usual recommended starting dose to avoid an excessive fall in blood pressure.

Since atenolol is excreted via the kidneys, dosage should be adjusted in cases of severe impairment of renal function. No significant accumulation of atenolol occurs until creatinine clearance falls below 35 mL/min/1.73m² (normal range is 100-150 mL/min/1.73m²); therefore, the following maximum dosages are recommended for patients with renal impairment.

Store at controlled room temperature, 20-25°C (68-77°F) [see USP]. Dispense in well-closed, light-resistant containers.

• Atenolol: Drug Profile
A cardiovascular drug used in the treatment of high blood pressure and angina pectoris. Browse through this information to learn what it is, how it works and any potential side effects.

• Tenormin: HealthSquare
Used in the treatment of high blood pressure and prophylaxis of angina pectoris, this drug is also known as Atenolol. Find out more about this anti-hypertensive drug as you browse through this informative site.

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	Volunteered (US Studies)		Total-Volunteered and Elicited (Foreign + US Studies)
	Atenolol (n = 164) %	Placebo (n = 206) %	Atenolol (n = 399) %	Placebo (n = 407) %

CARDIOVASCULAR
Bradycardia	3	0	3	0
Cold Extremities	0	0.5	12	5
Postural Hypotension	2	1	4	5
Leg Pain	0	0.5	3	1
CENTRAL NERVOUS
SYSTEM/
NEUROMUSCULAR
Dizziness	4	1	13	6
Vertigo	2	0.5	2	0.2
Light-Headedness	1	0	3	0.7
Tiredness	0.6	0.5	26	13
Fatigue	3	1	6	5
Lethargy	1	0	3	0.7
Drowsiness	0.6	0	2	0.5
Depression	0.6	0.5	12	9
Dreaming	0	0	3	1
GASTROINTESTINAL
Diarrhea	2	0	3	2
Nausea	4	1	3	1
RESPIRATORY (see Warnings)
Wheeziness	0	0	3	3
Dyspnea	0.6	1	6	4

Creatinine Clearance (mL/min/1.73m²)	Atenolol Elimination Half-life (hrs)	Maximum Dosage

15-35	16-27	50 mg daily
<15	>27	50 mg every other day

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Atenolol

Cardioprotective betablocker "par excellence"

Atenolol: Contraindications

Second and third degree heart block, manifest heart failure, cardiogenic shock.

Atenolol: Cautions

Atenolol should not be withdrawn suddenly from patients with coronary heart diseases (danger of increased ischemiae). Atenolol and clonidin should not be withdrawn simultaneously.