METOPROLOL TARTRATE 1 mg/mL Injection, Solution, 5 mL — NDC 51662-1478-1 (Billing 51662-1478-01)

WARNINGS Heart Failure Beta blockers, like metoprolol tartrate, can cause depression of myocardial contractility and may precipitate heart failure and cardiogenic shock. If signs or symptoms of heart failure develop, treat the patient according to recommended guidelines. It may be necessary to lower the dose of metoprolol tartrate or to discontinue it.

Use During Major Surgery Chronically administered beta-blocking therapy should not be routinely withdrawn prior to major surgery; however, the impaired ability of the heart to respond to reflex adrenergic stimuli may augment the risks of general anesthesia and surgical procedures. Bradycardia Bradycardia, including sinus pause, heart block, and cardiac arrest have occurred with the use of metoprolol tartrate. Patients with first-degree atrioventricular block, sinus node dysfunction, or conduction disorders may be at increased risk.

Monitor heart rate and rhythm in patients receiving metoprolol tartrate. If severe bradycardia develops, reduce or stop metoprolol tartrate. Exacerbation of Bronchospastic Disease Patients with bronchospastic disease, should, in general, not receive beta blockers, including metoprolol tartrate.

Because of its relative beta1 selectivity, however, metoprolol tartrate may be used in patients with bronchospastic disease who do not respond to, or cannot tolerate, other antihypertensive treatment. Because beta1 selectivity is not absolute use the lowest possible dose of metoprolol tartrate and consider administering metoprolol tartrate in smaller doses three times daily, instead of larger doses two times daily, to avoid the higher plasma levels associated with the longer dosing interval (see DOSAGE AND ADMINISTRATION).

Bronchodilators, including beta2 agonists, should be readily available or administered concomitantly. Diabetes and Hypoglycemia Beta blockers may mask tachycardia occurring with hypoglycemia, but other manifestations such as dizziness and sweating may not be significantly affected. Pheochromocytoma If metoprolol tartrate is used in the setting of pheochromocytoma, it should be given in combination with an alpha blocker, and only after the alpha blocker has been initiated.

Administration of beta blockers alone in the setting of pheochromocytoma has been associated with a paradoxical increase in blood pressure due to the attenuation of beta-mediated vasodilatation in skeletal muscle. Thyrotoxicosis Metoprolol tartrate may mask certain clinical signs (e.g., tachycardia) of hyperthyroidism. Avoid abrupt withdrawal of beta blockade, which might precipitate a thyroid storm.

WARNING

ADVERSE REACTIONS Hypertension and Angina These adverse reactions were reported for treatment with oral metoprolol tartrate. 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. Post-marketing 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 tartrate has not been definitely established). The oculomucocutaneous syndrome associated with the beta blocker practolol has not been reported with metoprolol tartrate.

Myocardial Infarction These adverse reactions were reported from treatment regimens where intravenous metoprolol tartrate was administered, when tolerated. 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 tartrate and placebo described in the CLINICAL PHARMACOLOGY section, the following adverse reactions were reported: 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 tartrate. 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, l… [Excerpted — this section continues on DailyMed.]

PRECAUTIONS Risk of Anaphylactic Reactions While taking beta blockers, patients with a history of severe anaphylactic reaction to a variety of allergens may be more reactive to repeated challenge, either accidental, diagnostic, or therapeutic. Such patients may be unresponsive to the usual doses of epinephrine used to treat allergic reaction. Information for Patients Advise patients (1) to avoid operating automobiles and machinery or engaging in other tasks requiring alertness until the patient's response to therapy with metoprolol tartrate has been determined; (2) to contact the physician if any difficulty in breathing occurs; (3) to inform the physician or dentist before any type of surgery that he or she is taking metoprolol tartrate.

Drug Interactions 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 tartrate 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. General Anesthetics Some inhalation anesthetics may enhance the cardiodepressant effect of beta-blockers. (See WARNINGS , Major Surgery).

CYP2D6 Inhibitors: Potent inhibitors of the CYP2D6 enzyme may increase the plasma concentration of metoprolol tartrate which would mimic the pharmacokinetics of CYP2D6 poor metabolizer (see CLINICAL PHARMACOKINETICS- 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 tartrate. 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 tartrate concurrently, and clonidine treatment is to be discontinued, stop metoprolol tartrate 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 te… [Excerpted — this section continues on DailyMed.]