Metoprolol Drug Information

Hypertension Individualize the dosage of metoprolol tartrate tablets. Metoprolol tartrate tablets should

be taken with or immediately following meals. The usual initial dosage is 100 mg daily in single or divided doses. Adjust 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 mg to 450 mg per day. Dosages above 450 mg per day have not been studied.

While once-daily dosing 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. Larger or more frequent daily doses may be required. Measure blood pressure near the end of the dosing interval to determine whether satisfactory control is being maintained throughout the day.

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 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 a 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, reduce the dosage gradually over a period of 1 to 2 weeks.

Myocardial Infarction See prescribing information of intravenous metoprolol for dosage instructions for

intravenous therapy. In patients who tolerate the full intravenous dose, initiate metoprolol tartrate tablets, 50 mg every 6 hours, 15 minutes after the last intravenous dose of metoprolol and continue for 48 hours. In the case of intolerance, reduce dose to 25 mg and administer for 48 hours.

Titrate, based on tolerability, to a maintenance dosage of 100 mg twice daily. Continue therapy for at least 3 months. Although the efficacy of metoprolol tartrate tablets 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.

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Hypertension and Angina Most adverse effects have been mild and transient. Central Nervous System: Tiredness and dizziness have occurred in about 10% of 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 patients. Cold extremities; arterial insufficiency, usually of the Raynaud type; palpitations; heart failure exacerbations; peripheral edema; and hypotension have been reported in about 1% of patients. Gangrene in patients with pre-existing severe peripheral circulatory disorders has also been reported.. Respiratory: Wheezing (bronchospasm) and dyspnea have been reported in about 1% of patients . Rhinitis has also been reported.

Gastrointestinal: Diarrhea has occurred in about 5% of patients. Nausea, dry mouth, gastric pain, constipation, flatulence, and heartburn have been reported in about 1% of patients. Vomiting was a common occurrence.

Hypersensitive Reactions: Pruritus or rash have occurred in about 5% of patients. Photosensitivity and worsening of psoriasis has been reported. Miscellaneous: Peyronie’s disease, musculoskeletal pain, blurred vision, and tinnitus has been reported.

Myocardial Infarction In general, the adverse reactions observed in trials with metoprolol in MI are consistent with the hypertension and angina experience. In a randomized comparison of metoprolol and placebo in the setting of acute MI the following adverse reactions were reported: Metoprolol Placebo Hypotension (systolic BP < 90 mm Hg) 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%

Post-Marketing Experience

The following adverse reactions have been identified during post approval use of metoprolol. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. 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. Hematologic: Agranulocytosis, nonthrombocytopenic purpura and thrombocytopenic purpura. Hypersensitive Reactions: Fever combined with aching and sore throat, laryngospasm and respiratory distress.

Laboratory Findings : Increase in blood triglycerides, elevated transaminase and decrease in High Density Lipoprotein (HDL)

Catecholamine Depleting Drugs Catecholamine depleting drugs (e.g., reserpine, monoamine oxidase (MAO) inhibitors)

may have an additive effect when given with beta-blocking agents. Observe patients treated with metoprolol plus a catecholamine depletor for evidence of hypotension or marked bradycardia, which may produce vertigo, syncope, or postural hypotension.

Epinephrine

While taking beta-blockers, patients with a history of severe anaphylactic reactions to a variety of allergens may be more reactive to repeated challenge and may be unresponsive to the usual doses of epinephrine used to treat an allergic reaction.

CYP2D6 Inhibitors Drugs that are strong inhibitors of

CYP2D6 such as quinidine, fluoxetine, paroxetine, and propafenone were shown to double metoprolol concentrations. While there is no information about moderate or weak inhibitors, these too are likely to increase metoprolol concentration. Increases in plasma concentration decrease the cardioselectivity of metoprolol.

Monitor patients closely, when the combination cannot be avoided.

Negative Chronotropes Digitalis glycosides, clonidine, diltiazem and verapamil slow atrioventricular conduction and

decrease heart rate. Concomitant use with beta-blockers can increase the risk of bradycardia. If clonidine and a beta-blocker, such as metoprolol are coadministered, withdraw the beta-blocker several days before the gradual withdrawal of clonidine because beta-blockers may exacerbate the rebound hypertension that can follow the withdrawal of clonidine.

If replacing clonidine by beta-blocker therapy, delay the introduction of beta-blockers for several days after clonidine administration has stopped.

Pregnancy Risk Summary Available data from published observational studies have not demonstrated an association of adverse developmental outcomes with maternal use of metoprolol during pregnancy ( see Data). Untreated hypertension and myocardial infarction during pregnancy can lead to adverse outcomes for the mother and the fetus (see Clinical Considerations). In animal reproduction studies, metoprolol has been shown to increase post-implantation loss and decrease neonatal survival in rats at oral dosages of 500 mg/kg/day, approximately 11 times the daily dose of 450 mg in a 60-kg patient on a mg/m 2 basis. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown.

In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Clinical consideration Disease-associated maternal and/or embryo/fetal risk Hypertension in pregnancy increases the maternal risk for pre-eclampsia, gestational diabetes, premature delivery, and delivery complications (e.g., need for cesarean section, and post-partum hemorrhage). Hypertension increases the fetal risk for intrauterine growth restriction and intrauterine death. Pregnant women with hypertension should be carefully monitored and managed accordingly.

Fetal/Neonatal adverse reactions Metoprolol crosses the placenta. Neonates born to mothers who are receiving metoprolol during pregnancy, may be at risk for hypotension, hypoglycemia, bradycardia, and respiratory depression. Observe neonates and manage accordingly.

Data Human Data Data from published observational studies did not demonstrate an association of major congenital malformations and use of metoprolol in pregnancy. The published literature has reported inconsistent findings of intrauterine growth retardation, preterm birth and perinatal mortality with maternal use of metoprolol during pregnancy; however, these studies have methodological limitations hindering interpretation. Methodological limitations include retrospective design, concomitant use of other medications, and other unadjusted confounders that may account for the study findings including the underlying disease in the mother.

These observational studies cannot definitely establish or exclude any drug-associated risk during pregnancy. Animal Data Metoprolol has been shown to increase post-implantation loss and decrease neonatal survival in rats at oral dosages of 500 mg/kg/day, i.e., 11 times, on a mg/m 2 basis, the daily dose of 450 mg in a 60-kg patient. No fetal abnormalities were observed when pregnant rats received metoprolol orally up to a dose of 200 mg/kg/day, i.e., 4 times, the daily dose of 400 mg in a 60-kg patient.

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

Metoprolol tartrate tablets are contraindicated in severe bradycardia, second- or third-degree heart block, cardiogenic shock, systolic blood pressure <100, decompensated heart failure, sick sinus syndrome (unless a permanent pacemaker is in place), and in patients who are hypersensitive to any component of this product. Known hypersensitivity to product components. Severe bradycardia: Greater than first degree heart block, or sick sinus syndrome without a pacemaker.

Cardiogenic shock or decompensated heart failure.

Signs and Symptoms - Overdosage of metoprolol may lead to severe bradycardia, hypotension, and cardiogenic shock. Clinical presentation can also include: atrioventricular block, heart failure, bronchospasm, hypoxia, impairment of consciousness/coma, nausea and vomiting. Treatment – Consider treating the patient with intensive care.

Patients with myocardial infarction or heart failure may be prone to significant hemodynamic instability. Beta-blocker overdose may result in significant resistance to resuscitation with adrenergic agents, including beta-agonists. On the basis of the pharmacologic actions of metoprolol, employ the following measures.

Hemodialysis is unlikely to make a useful contribution to metoprolol elimination. Bradycardia: Evaluate the need for atropine, adrenergic-stimulating drugs or pacemaker to treat bradycardia and conduction disorders. Hypotension: Treat underlying bradycardia.

Consider intravenous vasopressor infusion, such as dopamine or norepinephrine. Heart failure and shock: May be treated when appropriate with suitable volume expansion, injection of glucagon (if necessary, followed by an intravenous infusion of glucagon), intravenous administration of adrenergic drugs such as dobutamine, with α 1 receptor agonistic drugs added in presence of vasodilation. Bronchospasm: Can usually be reversed by bronchodilators.