METOPROLOL TARTRATE

Metoprolol tartrate USP is a selective beta 1 -adrenoreceptor blocking agent, available as 25, 50 and 100 mg tablets for oral administration. Metoprolol tartrate is (±)-1-(isopropylamino)-3-[ p -(2-methoxyethyl)phenoxy]-2-propanol (2:1) dextro -tartrate salt. Its structural formula is: Metoprolol tartrate USP is a white, practically odorless, crystalline powder with a molecular weight of 684.82. It is very soluble in water; freely soluble in methylene chloride, in chloroform, and in alcohol; slightly soluble in acetone; and insoluble in ether. Each tablet for oral administration contains 25 mg, 50 mg or 100 mg of metoprolol tartrate. The tablets contain the following inactive ingredients: microcrystalline cellulose, corn starch, sodium starch glycollate, colloidal silicon dioxide, sodium lauryl sulfate, talc, magnesium stearate, hypromellose, titanium dioxide, polyethylene glycol and polysorbate 80. In addition, 50 mg tablet contains D&C Red #30 Aluminium Lake and 100 mg tablet contains FD&C Blue #2 Aluminium Lake as coloring agents. metoprolol-structure

Hypertension Metoprolol tartrate tablets, USP are indicated for the treatment of hypertension. They may be used alone or in combination with other antihypertensive agents. Angina Pectoris Metoprolol tartrate tablets, USP are indicated in the long-term treatment of angina pectoris. Myocardial Infarction Metoprolol tartrate tablets, USP are indicated in the treatment of hemodynamically stable patients with definite or suspected acute myocardial infarction to reduce cardiovascular mortality when used alone or in conjunction with intravenous metoprolol. Oral metoprolol tartrate tablets, USP therapy can be initiated after intravenous metoprolol therapy or, alternatively, oral treatment can begin within 3 to 10 days of the acute event (see DOSAGE AND ADMINISTRATION , CONTRAINDICATIONS , and WARNINGS ).

Hypertension Individualized the dosage of metoprolol tartrate tablets. Metoprolol tartrate tablets should be taken with or immediately following meals. The usual initial dosage of metoprolol tartrate tablets is 100 mg daily in single or divided doses, whether used alone or added to a diuretic. Increase the dosage at weekly (or longer) intervals until optimum blood pressure reduction is achieved. In general, the maximum effect of any given dosage level will be apparent after 1 week of therapy. The effective dosage range of metoprolol tartrate tablets is 100 to 450 mg per day. Dosages above 450 mg per day have not been studied. While once-daily dosing is effective and can maintain a reduction in blood pressure throughout the day, lower doses (especially 100 mg) may not maintain a full effect at the end of the 24-hour period, and larger or more frequent daily doses may be required. This can be evaluated by measuring blood pressure near the end of the dosing interval to determine whether satisfactory control is being maintained throughout the day. Beta 1 selectivity diminishes as the dose of metoprolol is increased. Angina Pectoris The dosage of metoprolol tartrate tablets should be individualized. Metoprolol tartrate tablets should be taken with or immediately following meals. The usual initial dosage of metoprolol tartrate tablets is 100 mg daily, given in two divided doses. Gradually increase the dosage at weekly intervals until optimum clinical response has been obtained or there is pronounced slowing of the heart rate. The effective dosage range of metoprolol tartrate tablets is 100 to 400 mg per day. Dosages above 400 mg per day have not been studied. If treatment is to be discontinued, gradually decrease the dosage over a period of 1 to 2 weeks (see WARNINGS ). Myocardial Infarction Early Treatment During the early phase of definite or suspected acute myocardial infarction, initiate treatment with metoprolol tartrate tablets as soon as possible after the patient's arrival in the hospital. Such treatment should be initiated in a coronary care or similar unit immediately after the patient’s hemodynamic condition has stabilized. Begin treatment in this early phase with the intravenous administration of three bolus injections of 5 mg of metoprolol tartrate each; give the injections at approximately 2-minute intervals. During the intravenous administration of metoprolol, monitor blood pressure, heart rate, and electrocardiogram. In patients who tolerate the full intravenous dose (15 mg), initiate metoprolol tartrate tablets, 50 mg every 6 hours, 15 minutes after the last intravenous dose and continue for 48 hours. Thereafter, the maintenance dosage is 100 mg twice daily (see Late Treatment below). Start patients who appear not to tolerate the full intravenous dose on metoprolol tartrate tablets either 25 mg or 50 mg every 6 hours (depending on the degree of intolerance) 15 minutes after the last intravenous dose or as soon as their clinical condition allows. In patients with severe intolerance, discontinue metoprolol tartrate tablets (see WARNINGS ). Late Treatment Start patients with contraindications to treatment during the early phase of suspected or definite myocardial infarction, patients who appear not to tolerate the full early treatment, and patients in whom the physician wishes to delay therapy for any other reason on metoprolol tartrate tablets, 100 mg twice daily, as soon as their clinical condition allows. Continue therapy for at least 3 months. Although the efficacy of metoprolol beyond 3 months has not been conclusively established, data from studies with other beta-blockers suggest that treatment should be continued for 1 to 3 years. Special Populations Pediatric Patients : No pediatric studies have been performed. The safety and efficacy of metoprolol tartrate tablets in pediatric patients have not been established. Renal Impairment : No dose adjustment of metoprolol tartrate tablets is required in patients with renal impairment. Hepatic Impairment : Metoprolol blood levels are likely to increase substantially in patients with hepatic impairment. Therefore, metoprolol tartrate tablets should be initiated at low doses with cautious gradual dose titration according to clinical response. Geriatric Patients (>65 years) : In general, use a low initial starting dose in elderly patients given their greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. Method of Administration For oral treatment, the tablets should be swallowed un-chewed with a glass of water. Metoprolol tartrate tablets should always be taken in standardized relation with meals. If the physician asks the patient to take metoprolol tartrate tablets either before breakfast or with breakfast, then the patient should continue taking metoprolol with the same schedule during the course of therapy.

Hypertension and Angina Metoprolol tartrate tablets are contraindicated in sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure (see WARNINGS ). Hypersensitivity to metoprolol and related derivatives, or to any of the excipients; hypersensitivity to other beta-blockers (cross sensitivity between beta-blockers can occur). Sick-sinus Syndrome. Severe peripheral arterial circulatory disorders. Myocardial Infarction Metoprolol tartrate tablets are contraindicated in patients with a heart rate < 45 beats/min; second- and third-degree heart block; significant first-degree heart block (P-R interval ≥ 0.24 sec); systolic blood pressure < 100 mmHg; or moderate-to-severe cardiac failure (see WARNINGS ).

Hypertension and Angina Most adverse effects have been mild and transient. Central Nervous System: Tiredness and dizziness have occurred in about 10 of 100 patients. Depression has been reported in about 5 of 100 patients. Mental confusion and short-term memory loss have been reported. Headache, nightmares, and insomnia have also been reported. Cardiovascular: Shortness of breath and bradycardia have occurred in approximately 3 of 100 patients. Cold extremities; arterial insufficiency, usually of the Raynaud type; palpitations; congestive heart failure; peripheral edema; and hypotension have been reported in about 1 of 100 patients. Gangrene in patients with pre-existing severe peripheral circulatory disorders has also been reported very rarely. (See CONTRAINDICATIONS , WARNINGS , and PRECAUTIONS .) Respiratory: Wheezing (bronchospasm) and dyspnea have been reported in about 1 of 100 patients (see WARNINGS ). Rhinitis has also been reported. Gastrointestinal: Diarrhea has occurred in about 5 of 100 patients. Nausea, dry mouth, gastric pain, constipation, flatulence, and heartburn have been reported in about 1 of 100 patients. Vomiting was a common occurrence. Postmarketing experience reveals very rare reports of hepatitis, jaundice and non-specific hepatic dysfunction. Isolated cases of transaminase, alkaline phosphatase, and lactic dehydrogenase elevations have also been reported. Hypersensitive Reactions: Pruritus or rash have occurred in about 5 of 100 patients. Very rarely, photosensitivity and worsening of psoriasis has been reported. Miscellaneous: Peyronie’s disease has been reported in fewer than 1 of 100,000 patients. Musculoskeletal pain, blurred vision, and tinnitus have also been reported. There have been rare reports of reversible alopecia, agranulocytosis, and dry eyes. Discontinuation of the drug should be considered if any such reaction is not otherwise explicable. There have been very rare reports of weight gain, arthritis, and retroperitoneal fibrosis (relationship to metoprolol has not been definitely established). The oculomucocutaneous syndrome associated with the beta-blocker practolol has not been reported with metoprolol. Myocardial Infarction Central Nervous System: Tiredness has been reported in about 1 of 100 patients. Vertigo, sleep disturbances, hallucinations, headache, dizziness, visual disturbances, confusion, and reduced libido have also been reported, but a drug relationship is not clear. Cardiovascular: In the randomized comparison of metoprolol and placebo described in the CLINICAL PHARMACOLOGY section, the following adverse reactions were reported: Metoprolol Placebo Hypotension (systolic BP < 90 mmHg) 27.4% 23.2% Bradycardia (heart rate <40 beats/min) 15.9% 6.7% Second- or third-degree heart block 4.7% 4.7% First-degree heart block (P-R ≥0.26 sec) 5.3% 1.9% Heart failure 27.5% 29.6% Respiratory: Dyspnea of pulmonary origin has been reported in fewer than 1 of 100 patients. Gastrointestinal: Nausea and abdominal pain have been reported in fewer than 1 of 100 patients. Dermatologic: Rash and worsened psoriasis have been reported, but a drug relationship is not clear. Miscellaneous: Unstable diabetes and claudication have been reported, but a drug relationship is not clear. Potential Adverse Reactions A variety of adverse reactions not listed above have been reported with other beta-adrenergic blocking agents and should be considered potential adverse reactions to metoprolol. Central 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, and decreased performance on neuropsychometrics. Cardiovascular: Intensification of AV block (see CONTRAINDICATIONS ). Hematologic: Agranulocytosis, nonthrombocytopenic purpura and thrombocytopenic purpura. Hypersensitive Reactions: Fever combined with aching and sore throat, laryngospasm and respiratory distress. Postmarketing Experience The following adverse reactions have been reported during postapproval use of metoprolol: confusional state, an increase in blood triglycerides and a decrease in High Density Lipoprotein (HDL). Because these reports are from a population of uncertain size and are subject to confounding factors, it is not possible to reliably estimate their frequency.

Catecholamine-depleting Drugs: Catecholamine-depleting drugs (e.g., reserpine) may have an additive effect when given with beta-blocking agents or monoamine oxidase (MAO) inhibitors. Observe patients treated with metoprolol plus a catecholamine depletor for evidence of hypotension or marked bradycardia, which may produce vertigo, syncope, or postural hypotension. In addition, possibly significant hypertension may theoretically occur up to 14 days following discontinuation of the concomitant administration with an irreversible MAO inhibitor. Digitalis Glycosides and Beta-blockers: Both digitalis glycosides and beta-blockers slow atrioventricular conduction and decrease heart rate. Concomitant use can increase the risk of bradycardia. Monitor heart rate and PR interval. Calcium Channel Blockers: Concomitant administration of a beta-adrenergic antagonist with a calcium channel blocker may produce an additive reduction in myocardial contractility because of negative chronotropic and inotropic effects. CYP2D6 Inhibitors: Potent inhibitors of the CYP2D6 enzyme may increase the plasma concentration of metoprolol which would mimic the pharmacokinetics of CYP2D6 poor metabolizer (see Pharmacokinetics section). Increase in plasma concentrations of metoprolol would decrease the cardioselectivity of metoprolol. Known clinically significant potent inhibitors of CYP2D6 are antidepressants such as fluvoxamine, fluoxetine, paroxetine, sertraline, bupropion, clomipramine, and desipramine; antipsychotics such as chlorpromazine, fluphenazine, haloperidol, and thioridazine; antiarrhythmics such as quinidine or propafenone; antiretrovirals such as ritonavir; antihistamines such as diphenhydramine; antimalarials such as hydroxychloroquine or quinidine; antifungals such as terbinafine. Hydralazine: Concomitant administration of hydralazine may inhibit presystemic metabolism of metoprolol leading to increased concentrations of metoprolol. Alpha-adrenergic Agents: Antihypertensive effect of alpha-adrenergic blockers such as guanethidine, betanidine, reserpine, alpha-methyldopa or clonidine may be potentiated by beta-blockers including metoprolol. Beta-adrenergic blockers may also potentiate the postural hypotensive effect of the first dose of prazosin, probably by preventing reflex tachycardia. On the contrary, beta adrenergic blockers may also potentiate the hypertensive response to withdrawal of clonidine in patients receiving concomitant clonidine and beta-adrenergic blocker. If a patient is treated with clonidine and metoprolol concurrently, and clonidine treatment is to be discontinued, stop metoprolol several days before clonidine is withdrawn. Rebound hypertension that can follow withdrawal of clonidine may be increased in patients receiving concurrent beta-blocker treatment. Ergot Alkaloid: Concomitant administration with beta-blockers may enhance the vasoconstrictive action of ergot alkaloids. Dipyridamole: In general, administration of a beta-blocker should be withheld before dipyridamole testing, with careful monitoring of heart rate following the dipyridamole injection.