Metoprolol succinate

Description

Metoprolol succinate is a beta 1-selective (cardioselective) adrenoceptor blocking agent intended for oral administration, available as extended-release tablets. These tablets are formulated to provide a controlled and predictable release of metoprolol, allowing for once-daily dosing. The formulation consists of a multiple unit system containing metoprolol succinate in numerous controlled release pellets, with each pellet functioning as an independent drug delivery unit designed to release metoprolol continuously throughout the dosage interval.

Metoprolol succinate is available in dosages of 23.75 mg, 47.5 mg, 95 mg, and 190 mg, which are equivalent to 25 mg, 50 mg, 100 mg, and 200 mg of metoprolol tartrate, respectively. The chemical name of metoprolol succinate is (±)1-(isopropyl amino)-3-p-(2-methoxyethyl)phenoxy-2-propanol succinate (2:1) (salt), and its structural formula is represented accordingly. Metoprolol succinate, USP, appears as a white crystalline powder with a molecular weight of 652.8. It is freely soluble in water, soluble in methanol, sparingly soluble in ethanol, and slightly soluble in dichloromethane and 2-propanol. It is practically insoluble in ethyl acetate, acetone, diethyl ether, and heptane.

Inactive ingredients in the formulation include colloidal silicon dioxide, crospovidone, ethylcellulose, hypromellose, lactose monohydrate (25 mg and 50 mg), magnesium stearate, microcrystalline cellulose, polyethylene glycol, polyvinyl alcohol-partially hydrolyzed, sugar spheres (composed of corn starch and sucrose), talc, titanium dioxide, and triethyl citrate. The FDA-approved dissolution test specifications for this product differ from those outlined in the USP.

Uses and Indications

Metoprolol succinate is indicated for the treatment of hypertension, angina pectoris, and heart failure. In patients with hypertension, this medication is utilized to lower blood pressure, thereby reducing the risk of both fatal and non-fatal cardiovascular events, including strokes and myocardial infarctions. For patients experiencing angina pectoris, metoprolol succinate serves to alleviate symptoms associated with this condition. Additionally, in the context of heart failure, this drug is indicated to reduce the risk of cardiovascular mortality and hospitalizations due to heart failure.

There are no teratogenic or nonteratogenic effects associated with metoprolol succinate.

Dosage and Administration

The medication is to be administered once daily. Dosing should be titrated at weekly or longer intervals as needed and tolerated.

For the management of hypertension, the starting dose is between 25 mg and 100 mg. In cases of angina pectoris, the recommended starting dose is 100 mg. For heart failure, the initial dose may be either 12.5 mg or 25 mg, depending on the patient's condition and response.

When transitioning from immediate-release metoprolol to metoprolol succinate extended-release tablets, it is essential to maintain the same total daily dose of metoprolol succinate extended-release tablets as the patient was receiving with the immediate-release formulation.

Contraindications

Use of this product is contraindicated in patients with known hypersensitivity to any of its components. Additionally, it should not be administered to individuals with severe bradycardia, including those with greater than first-degree heart block or sick sinus syndrome without a pacemaker. The product is also contraindicated in cases of cardiogenic shock or decompensated heart failure, as these conditions may exacerbate the risks associated with its use.

Warnings and Precautions

Abrupt cessation of beta-blocker therapy may lead to exacerbation of myocardial ischemia. Therefore, healthcare professionals should exercise caution when discontinuing treatment, particularly in patients with a history of coronary artery disease.

In patients with heart failure, there is a risk of worsening cardiac function. Continuous monitoring of cardiac status is recommended to identify any deterioration in heart failure symptoms.

For individuals with bronchospastic disease, the use of beta-blockers is contraindicated due to the potential for bronchospasm. Alternative therapies should be considered for these patients.

Concomitant administration of beta-blockers with glycosides, clonidine, diltiazem, or verapamil may increase the risk of bradycardia. Close monitoring of heart rate and rhythm is advised when these medications are used together.

In patients diagnosed with pheochromocytoma, it is essential to initiate therapy with an alpha-blocker prior to starting beta-blocker treatment to prevent hypertensive crises.

During major surgery, particularly non-cardiac procedures, the initiation of high-dose extended-release metoprolol should be avoided. However, it is not necessary to routinely withdraw chronic beta-blocker therapy before surgery, as this may lead to adverse cardiovascular events.

Patients receiving beta-blockers may experience an increased risk of hypoglycemia, and these medications can mask the early warning signs of low blood sugar. Regular monitoring of blood glucose levels is recommended, especially in diabetic patients.

In cases of thyrotoxicosis, abrupt withdrawal of beta-blockers may precipitate a thyroid storm, a life-threatening condition. Caution should be exercised, and gradual tapering may be necessary.

For patients with peripheral vascular disease, beta-blockers can exacerbate symptoms of arterial insufficiency. Monitoring of peripheral circulation is advised to assess for any worsening of symptoms.

Lastly, patients treated with beta-blockers may exhibit unresponsiveness to the usual doses of epinephrine used for the management of allergic reactions. Healthcare providers should be aware of this potential interaction and consider alternative treatment strategies in such scenarios.

Side Effects

Patients receiving treatment may experience a range of adverse reactions. The most common adverse reactions reported include tiredness, dizziness, depression, shortness of breath, bradycardia, hypotension, diarrhea, pruritus, and rash.

Serious adverse reactions have also been noted. Worsening cardiac failure may occur in patients with pre-existing heart conditions. Abrupt cessation of therapy can exacerbate myocardial ischemia, and patients with bronchospastic disease should avoid beta-blockers due to the risk of bronchospasm. Additionally, the concomitant use of glycosides, clonidine, diltiazem, and verapamil with beta-blockers may increase the risk of bradycardia.

In patients with pheochromocytoma, it is recommended to initiate therapy with an alpha-blocker. For those undergoing major surgery, the initiation of high-dose extended-release metoprolol should be avoided, and chronic beta-blocker therapy should not routinely be withdrawn prior to surgery. Patients with a history of hypoglycemia may experience an increased risk for hypoglycemia and may have masked early warning signs. Abrupt withdrawal in patients with thyrotoxicosis could precipitate a thyroid storm, and those with peripheral vascular disease may find that symptoms of arterial insufficiency are aggravated.

In cases of overdosage, patients may present with severe bradycardia, hypotension, and cardiogenic shock. Other clinical manifestations can include atrioventricular block, heart failure, bronchospasm, hypoxia, impairment of consciousness or coma, as well as nausea and vomiting. It is important to note that patients may be unresponsive to the usual doses of epinephrine used to treat allergic reactions.

Drug Interactions

Catecholamine-depleting drugs, when administered concurrently with beta-blocking agents, may produce an additive effect. This interaction necessitates careful monitoring of blood pressure and heart rate, as the combined effects could lead to significant cardiovascular changes.

CYP2D6 inhibitors are known to increase the concentration of metoprolol. Clinicians should consider dosage adjustments of metoprolol when initiating or discontinuing CYP2D6 inhibitors to avoid potential adverse effects associated with elevated drug levels.

Additionally, beta-blockers, including metoprolol, may exacerbate rebound hypertension following the withdrawal of clonidine. It is advisable to monitor patients closely for signs of increased blood pressure during the tapering process of clonidine therapy, and to manage any rebound effects appropriately.

Packaging & NDC

The table below lists all NDC Code configurations of Metoprolol Succinate, the U.S. brand-name prescription product. Columns show Packaging, Formulation Type, and Active Ingredient Strength.

Pediatric Use

One hundred forty-four hypertensive pediatric patients aged 6 to 16 years were randomized to receive either placebo or one of three dose levels of metoprolol succinate extended-release tablets (0.2, 1, or 2 mg/kg once daily) and were followed for 4 weeks. The safety and effectiveness of metoprolol succinate extended-release tablets have not been established in patients younger than 6 years of age. In pediatric patients aged 6 to 16 years, no clinically relevant differences in the adverse event profile were observed when compared to adult patients.

Geriatric Use

Clinical studies of metoprolol succinate extended-release tablets in hypertension did not include a sufficient number of subjects aged 65 and over to determine whether these elderly patients respond differently from younger individuals. However, other reported clinical experiences in hypertensive patients have not identified significant differences in responses between elderly and younger patients.

In the MERIT-HF trial, which randomized 1,990 patients with heart failure to metoprolol succinate extended-release tablets, 50% (990) of the participants were aged 65 years and older, with 12% (238) being 75 years of age and older. The findings from this trial indicated no notable differences in efficacy or the rate of adverse reactions between older and younger patients.

Given the greater frequency of decreased hepatic, renal, or cardiac function, as well as the presence of concomitant diseases or other drug therapies in geriatric patients, it is generally recommended to initiate treatment with a low starting dose in this population. Careful monitoring is advised to ensure safety and efficacy in elderly patients receiving metoprolol succinate extended-release tablets.

Pregnancy

Untreated hypertension and heart failure during pregnancy can lead to adverse outcomes for both the mother and the fetus. Available data from published observational studies have not demonstrated a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes with the use of metoprolol during pregnancy. However, there are inconsistent reports regarding intrauterine growth restriction, preterm birth, and perinatal mortality associated with maternal use of beta-blockers, including metoprolol.

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, which is approximately 24 times the daily dose of 200 mg in a 60-kg patient on a mg/m² basis. Conversely, no fetal abnormalities were observed when pregnant rats received metoprolol orally at doses up to 200 mg/kg/day, equivalent to 10 times the daily dose of 200 mg in a 60-kg patient.

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown; however, all pregnancies carry a background risk of birth defects, loss, or other adverse outcomes. 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. Hypertension in pregnancy increases the maternal risk for pre-eclampsia, gestational diabetes, premature delivery, and delivery complications, such as the need for cesarean section and post-partum hemorrhage. Additionally, hypertension increases the fetal risk for intrauterine growth restriction and intrauterine death, necessitating careful monitoring and management of pregnant women with hypertension.

Metoprolol crosses the placenta, and neonates born to mothers receiving metoprolol during pregnancy may be at risk for hypotension, hypoglycemia, bradycardia, and respiratory depression. Therefore, it is essential to observe neonates and manage them accordingly. While data from published observational studies did not demonstrate an association of major congenital malformations with the use of metoprolol in pregnancy, the inconsistent findings regarding intrauterine growth retardation, preterm birth, and perinatal mortality highlight the need for cautious interpretation due to methodological limitations in these studies.

Lactation

Metoprolol crosses into breast milk. Although specific data on the effects of metoprolol on breastfed infants are not available, caution is advised when administering this medication to lactating mothers.

Neonates born to mothers receiving metoprolol during pregnancy may be at risk for hypotension, hypoglycemia, bradycardia, and respiratory depression. Therefore, it is recommended that healthcare professionals observe breastfed infants for any potential adverse effects and manage them accordingly.

Renal Impairment

There is no specific information available regarding dosage adjustments, special monitoring, or safety considerations for patients with renal impairment. Healthcare professionals should exercise caution when prescribing to patients with reduced kidney function, as the absence of detailed guidance necessitates careful clinical judgment. Regular monitoring of renal function may be advisable in these patients to ensure safety and efficacy.

Hepatic Impairment

Patients with hepatic impairment have not been specifically studied in relation to the use of this medication. Consequently, there are no established dosage adjustments, special monitoring requirements, or precautions outlined for individuals with compromised liver function. It is recommended that healthcare providers exercise caution when prescribing this medication to patients with hepatic impairment, given the lack of data on its safety and efficacy in this population. Regular monitoring of liver function may be prudent in these cases, although specific parameters are not defined in the available information.

Overdosage

Overdosage of metoprolol succinate extended-release tablets can result in a range of serious clinical manifestations. The most notable signs and symptoms include severe bradycardia, hypotension, and cardiogenic shock. Additional clinical presentations may encompass atrioventricular block, heart failure, bronchospasm, hypoxia, impairment of consciousness or coma, as well as gastrointestinal symptoms such as nausea and vomiting.

In the event of an overdose, it is crucial to consider intensive care management for the patient. Those with underlying conditions such as myocardial infarction or heart failure may experience significant hemodynamic instability, necessitating close monitoring and intervention. It is important to note that beta-blocker overdose can lead to considerable resistance to resuscitation efforts with adrenergic agents, including beta-agonists.

Management strategies should be tailored based on the pharmacologic actions of metoprolol.

Bradycardia

For bradycardia, healthcare professionals should assess the need for atropine, adrenergic-stimulating drugs, or the placement of a pacemaker to address bradycardia and conduction disorders.

Hypotension

In cases of hypotension, it is essential to treat the underlying bradycardia. Consideration should be given to intravenous vasopressor infusion, utilizing agents such as dopamine or norepinephrine.

Heart Failure and Shock

Heart failure and shock may be managed with appropriate volume expansion. If necessary, glucagon can be administered as an injection, followed by an intravenous infusion. Additionally, intravenous administration of adrenergic drugs such as dobutamine may be warranted, with α1 receptor agonistic drugs introduced in the presence of vasodilation.

Bronchospasm

Bronchospasm associated with overdose can typically be reversed with the use of bronchodilators.

It is important to note that hemodialysis is unlikely to significantly enhance the elimination of metoprolol from the body. Therefore, supportive care and symptomatic management remain the cornerstone of treatment in cases of metoprolol overdose.

Nonclinical Toxicology

Long-term studies in animals have been conducted to evaluate the carcinogenic potential of metoprolol tartrate. In 2-year studies in rats at three oral dosage levels of up to 800 mg/kg/day (41 times, on a mg/m² basis, the daily dose of 200 mg for a 60-kg patient), there was no increase in the development of spontaneously occurring benign or malignant neoplasms of any type. The only histologic changes that appeared to be drug-related were an increased incidence of generally mild focal accumulation of foamy macrophages in pulmonary alveoli and a slight increase in biliary hyperplasia. In a 21-month study in Swiss albino mice at three oral dosage levels of up to 750 mg/kg/day (18 times, on a mg/m² basis, the daily dose of 200 mg for a 60-kg patient), benign lung tumors (small adenomas) occurred more frequently in female mice receiving the highest dose than in untreated control animals. There was no increase in malignant or total (benign plus malignant) lung tumors, nor in the overall incidence of tumors or malignant tumors. This 21-month study was repeated in CD-1 mice, and no statistically or biologically significant differences were observed between treated and control mice of either sex for any type of tumor.

All genotoxicity tests performed on metoprolol tartrate, including a dominant lethal study in mice, chromosome studies in somatic cells, a Salmonella/mammalian-microsome mutagenicity test, and a nucleus anomaly test in somatic interphase nuclei, were negative. Additionally, metoprolol succinate was also evaluated in a Salmonella/mammalian-microsome mutagenicity test, which yielded negative results.

No evidence of impaired fertility due to metoprolol tartrate was observed in a study performed in rats at doses up to 22 times, on a mg/m² basis, the daily dose of 200 mg in a 60-kg patient.

Postmarketing Experience

No specific postmarketing experience details or adverse reactions have been reported in the available data.

Patient Counseling

Patients should be advised to take metoprolol succinate extended-release tablets regularly and continuously, as directed, preferably with or immediately following meals. In the event that a dose is missed, patients should take only the next scheduled dose and should not double the dose. It is important for patients to understand that they should not interrupt or discontinue metoprolol succinate extended-release tablets without first consulting their physician.

Healthcare providers should inform patients to avoid operating automobiles and machinery or engaging in other tasks that require alertness until their response to therapy with metoprolol succinate extended-release tablets has been determined. Patients should be instructed to contact their physician if they experience any difficulty in breathing. Additionally, patients should inform their physician or dentist prior to any type of surgery that they are taking metoprolol succinate extended-release tablets.

For patients with heart failure, it is crucial to advise them to consult their physician if they experience signs or symptoms of worsening heart failure, such as weight gain or increasing shortness of breath. Patients or caregivers should also be informed about the risk of hypoglycemia when metoprolol succinate extended-release tablets are administered to patients who are fasting or vomiting. It is essential to instruct patients or caregivers on how to monitor for signs of hypoglycemia.

Storage and Handling

The product is supplied in accordance with the following specifications: it should be stored at a temperature range of 20° to 25°C (68° to 77°F), with permissible excursions between 15° to 30°C (59° to 86°F) as defined by USP Controlled Room Temperature guidelines.

It is essential to keep this medication out of the reach of children to ensure safety.

Additional Clinical Information

Patients should be advised not to interrupt therapy without consulting their physician. In the event of severe hypoglycemia, it is crucial for patients to seek emergency treatment. No further information is available regarding laboratory tests, abuse potential, route, method, and frequency of administration, or postmarketing experience.

FDA Insert (PDF)

This document is the official FDA-approved prescribing information for Metoprolol Succinate as submitted by Epic Pharma, LLC. It includes detailed information about indications, dosage, contraindications, warnings, and clinical pharmacology.

View full prescribing information (PDF)