Atenolol and Chlorthalidone

INDICATIONS AND USAGE Atenolol and Chlorthalidone Tablets, USP are indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure lowers the risk of fatal and non-fatal cardiovascular events, primarily strokes and myocardial infarctions. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes including atenolol and chlorthalidone. Control of high blood pressure should be part of comprehensive cardiovascular risk management, including, as appropriate, lipid control, diabetes management, antithrombotic therapy, smoking cessation, exercise, and limited sodium intake. Many patients will require more than 1 drug to achieve blood pressure goals. For specific advice on goals and management, see published guidelines, such as those of the National High Blood Pressure Education Program’s Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC). Numerous antihypertensive drugs, from a variety of pharmacologic classes and with different mechanisms of action, have been shown in randomized controlled trials to reduce cardiovascular morbidity and mortality, and it can be concluded that it is blood pressure reduction, and not some other pharmacologic property of the drugs, that is largely responsible for those benefits. The largest and most consistent cardiovascular outcome benefit has been a reduction in the risk of stroke, but reductions in myocardial infarction and cardiovascular mortality also have been seen regularly. Elevated systolic or diastolic pressure causes increased cardiovascular risk, and the absolute risk increase per mmHg is greater at higher blood pressures, so that even modest reductions of severe hypertension can provide substantial benefit. Relative risk reduction from blood pressure reduction is similar across populations with varying absolute risk, so the absolute benefit is greater in patients who are at higher risk independent of their hypertension (for example, patients with diabetes or hyperlipidemia), and such patients would be expected to benefit from more aggressive treatment to a lower blood pressure goal. Some antihypertensive drugs have smaller blood pressure effects (as monotherapy) in black patients, and many antihypertensive drugs have additional approved indications and effects (e.g., on angina, heart failure, or diabetic kidney disease). These considerations may guide selection of therapy. 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.

DOSAGE AND ADMINISTRATION DOSAGE MUST BE INDIVIDUALIZED. (See INDICATIONS AND USAGE .) 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 Atenolol and Chlorthalidone Tablet, USP 50 mg/25 mg given once a day. If an optimal response is not achieved, the dosage should be increased to one Atenolol and Chlorthalidone Tablet, USP 100 mg/25 mg 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/1.73m 2 (normal range is 100 mL/min/1.73m 2 to 150 mL/min/1.73m 2 ); therefore, the following maximum dosages are recommended for patients with renal impairment. Creatinine Clearance (mL/min/1.73m2) Atenolol Elimination Half-Life (hrs) Maximum Dosage 15-35 16-27 50 mg daily 27 50 mg every other day

CONTRAINDICATIONS Atenolol and chlorthalidone tablets are 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.

ADVERSE REACTIONS Atenolol and chlorthalidone is usually well tolerated in properly selected patients. Most adverse effects have been mild and transient. The adverse effects observed for atenolol and chlorthalidone 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, e.g., 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. 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 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, visual disturbance, sick sinus syndrome, and dry mouth. Atenolol and chlorthalidone, like other beta-blockers, has been associated with the development of antinuclear antibodies (ANA), lupus syndrome, and Raynaud’s phenomenon. 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 atenolol and chlorthalidone conducted in the United States (89 patients treated with atenolol and chlorthalidone) 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. 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 synd …

Drug Interactions Atenolol and chlorthalidone tablets may potentiate the action of other antihypertensive agents used concomitantly. Patients treated with atenolol and chlorthalidone tablets plus a catecholamine depletor (e.g., 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 atenolol and chlorthalidone tablets (See WARNINGS .) Disopyramide is a Type I antiarrhythmic drug with potent negative inotropic and chronotropic effects. Disopyramide has been associated with severe bradycardia, asystole and heart failure when administered with beta-blockers. Amiodarone is an antiarrhythmic agent with negative chronotropic properties that may be additive to those seen with beta-blockers. 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. Concomitant use of prostaglandin synthase inhibiting drugs, e.g., indomethacin, may decrease the hypotensive effects of beta-blockers. Lithium generally should not be given with diuretics because they reduce its renal clearance and add a high risk of lithium toxicity. Read prescribing information for lithium preparations before use of such preparations with atenolol and chlorthalidone tablets. 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. Both digitalis glycosides and beta-blockers slow atrioventricular conduction and decrease heart rate. Concomitant use can increase the risk of bradycardia.

DESCRIPTION Atenolol and chlorthalidone tablets, USP are for the treatment of hypertension. It combines the antihypertensive activity of two agents: a beta 1 -selective (cardioselective) hydrophilic blocking agent (atenolol), and a monosulfonamyl diuretic (chlorthalidone). Atenolol, USP is Benzeneacetamide, 4-[2’-hydroxy-3’-[(1-methylethyl)amino]propoxy]-. It has the following structural formula: C 14 H 22 N 2 O 3 M.W. 266.34 Atenolol, USP (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, USP is 2-Chloro-5-(1-hydroxy-3-oxo-1-isoindolinyl) benzene sulfonamide. Chlorthalidone, USP has a water solubility of 12 mg/100 mL at 20°C. It has the following structural formula: C 14 H 11 ClN 2 O 4 S M.W. 338.77 Each atenolol and chlorthalidone tablet, USP 50 mg/25 mg for oral administration contains: atenolol USP, 50 mg and chlorthalidone USP, 25 mg. Each atenolol and chlorthalidone tablet, USP 100 mg/25 mg for oral administration contains: atenolol USP, 100 mg and chlorthalidone USP, 25 mg. Atenolol and chlorthalidone tablets USP, 50 mg/25 mg and 100 mg/25 mg, contain the following inactive ingredients: magnesium stearate, microcrystalline cellulose, povidone and sodium starch glycolate. 1 2

OVERDOSAGE No specific information is available with regard to overdosage and atenolol and chlorthalidone tablets 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 mg to 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 mg/h to 10 mg/h depending on response. HEART BLOCK (SECOND OR THIRD DEGREE): Isoproterenol or transvenous pacemaker. 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 beta 2 -stimulant such as isoproterenol or terbutaline and/or aminophylline. HYPOGLYCEMIA: Intravenous glucose. 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.

HOW SUPPLIED Atenolol and Chlorthalidone Tablets, USP are uncoated tablets. Atenolol and Chlorthalidone Tablets USP, 50 mg/25 mg are white to off white, round, biconvex, bevelled tablets, with debossing of '11' above breakline and '67' below breakline on one side and plain on the other side and are supplied as follows: NDC 70710-1167-1 in bottle of 100 tablets with child-resistant closure Atenolol and Chlorthalidone Tablets USP, 100 mg/25 mg are white to off white, round, biconvex, beveled tablets, with debossing of '11' over '68' on one side and plain on the other side and are supplied as follows: NDC 70710-1168-1 in bottle of 100 tablets with child-resistant closure Store at 20°C to 25°C (68°F to 77°F) [See USP Controlled Room Temperature]. Dispense in well-closed, light-resistant containers. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. Please address medical inquiries to, MedicalAffairs@zydususa.com or Tel.: 1-877-993-8779 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.