Metoprolol succinate

Description

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

The extended-release tablets are available in two strengths: 23.75 mg and 47.5 mg of metoprolol succinate, which are equivalent to 25 mg and 50 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 provided in the accompanying documentation. Metoprolol succinate, USP appears as a white to off-white powder with a molecular weight of 652.8. It is freely soluble in water and soluble in methanol. The formulation includes inactive ingredients such as acetyl tributyl citrate, colloidal silicon dioxide, croscarmellose sodium, ethyl cellulose, hydrogenated vegetable oil, hydroxypropyl cellulose, hypromellose, methylene chloride, microcrystalline cellulose, polyethylene glycol, sodium stearyl fumarate, talc, and titanium dioxide.

Uses and Indications

Metoprolol succinate extended-release tablets are indicated for the treatment of hypertension, angina pectoris, and heart failure.

This drug is indicated for hypertension to lower blood pressure, thereby reducing the risk of fatal and non-fatal cardiovascular events, primarily strokes and myocardial infarctions. It is also indicated for the management of angina pectoris. In patients with heart failure, metoprolol succinate extended-release tablets are indicated to reduce the risk of cardiovascular mortality and hospitalizations due to heart failure.

There are no teratogenic or nonteratogenic effects associated with this medication.

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 25 to 100 mg. In cases of angina pectoris, the recommended starting dose is 100 mg. For heart failure, the initial dosing should be either 12.5 or 25 mg.

When transitioning from immediate-release metoprolol to metoprolol succinate extended-release tablets, the same total daily dose of metoprolol succinate extended-release tablets should be utilized.

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 who do not have a pacemaker.

The product is also contraindicated in patients experiencing cardiogenic shock or decompensated heart failure, as these conditions may exacerbate potential adverse effects.

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. Additionally, chronic beta-blocker therapy should not be routinely withdrawn prior to surgery, as this may lead to adverse cardiovascular events.

Patients on 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. Therefore, careful management and gradual tapering of the medication are advised in these patients.

For individuals with peripheral vascular disease, beta-blockers may exacerbate symptoms of arterial insufficiency. Monitoring of peripheral circulation is recommended to assess for any worsening of symptoms.

Lastly, patients receiving beta-blockers may exhibit unresponsiveness to the standard doses of epinephrine used in the treatment 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 their symptoms of arterial insufficiency aggravated.

In the event 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, 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 may exhibit an additive effect when administered concurrently with beta-blocking agents. This interaction could potentially enhance the pharmacological effects of both drug classes, necessitating careful monitoring of the patient's response and blood pressure.

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.

Beta-blockers, including metoprolol, may worsen rebound hypertension following the withdrawal of clonidine. It is advisable to monitor blood pressure closely in patients transitioning off clonidine, particularly if they are concurrently receiving beta-blockers, to manage any potential increases in blood pressure effectively.

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 (0.2, 1, or 2 mg/kg once daily) over a 4-week period. The study did not achieve its primary endpoint of demonstrating a dose response for reduction in systolic blood pressure (SBP). However, some pre-specified secondary endpoints indicated effectiveness, including a dose-response for reduction in diastolic blood pressure (DBP) and significant changes in SBP when comparing 1 mg/kg and 2 mg/kg doses to placebo.

The mean placebo-corrected reductions in SBP ranged from 3 to 6 mmHg, while reductions in DBP ranged from 1 to 5 mmHg. Additionally, the mean reduction in heart rate was between 5 to 7 bpm, with some individuals experiencing considerably greater reductions.

No clinically relevant differences in the adverse event profile were observed in pediatric patients aged 6 to 16 years compared to adult patients. It is important to note that the safety and effectiveness of metoprolol succinate extended-release tablets have not been established in patients younger than 6 years of age.

Geriatric Use

Clinical studies evaluating the efficacy of metoprolol succinate extended-release in the treatment of hypertension did not include a sufficient number of subjects aged 65 and older to ascertain whether this population responds differently compared to younger individuals. However, other clinical experiences with hypertensive patients have not indicated any significant differences in responses between elderly and younger patients.

In the MERIT-HF trial, which involved 1,990 patients with heart failure randomized to receive metoprolol succinate extended-release, 50% of the participants were aged 65 years and older, and 12% were aged 75 years and older. The findings from this trial revealed no notable differences in efficacy or the incidence of adverse reactions between older and younger patients.

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

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 elevates 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 recommended that neonates be observed and managed 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 of the available literature, which may have methodological limitations.

Lactation

Metoprolol crosses the placenta. Lactating mothers receiving metoprolol should be aware that neonates born to them may be at risk for hypotension, hypoglycemia, bradycardia, and respiratory depression. It is important to observe breastfed infants for these potential 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 this patient population.

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 severe clinical manifestations. The most notable signs and symptoms include severe bradycardia, hypotension, and cardiogenic shock. Additionally, patients may present with atrioventricular block, heart failure, bronchospasm, hypoxia, and varying levels of consciousness, including coma. Gastrointestinal symptoms such as nausea and vomiting may also occur.

In the event of an overdose, it is crucial to consider intensive care management, particularly for patients with underlying conditions such as myocardial infarction or heart failure, as they may experience significant hemodynamic instability. 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 and associated conduction disorders, the need for atropine should be evaluated. In cases where bradycardia persists, the use of adrenergic-stimulating drugs or the placement of a pacemaker may be necessary.

Hypotension

Management of hypotension should focus on addressing the underlying bradycardia. Intravenous vasopressor infusion, such as dopamine or norepinephrine, may be warranted to stabilize blood pressure.

Heart Failure and Shock

In instances of heart failure and shock, appropriate treatment may include volume expansion and the administration of glucagon. If glucagon is utilized, an intravenous infusion may be required following the initial injection. Additionally, intravenous administration of adrenergic drugs such as dobutamine may be indicated, with α1 receptor agonists considered in the presence of vasodilation.

Bronchospasm

Bronchospasm associated with metoprolol overdose can typically be reversed with bronchodilators.

It is important to note that hemodialysis is unlikely to significantly enhance the elimination of metoprolol from the body. Therefore, supportive care and the aforementioned interventions are critical in managing an overdose effectively.

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 tested in a Salmonella/mammalian-microsome mutagenicity test, yielding 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 have been reported. As such, there are no additional adverse events or rare case reports to summarize at this time.

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 the use of 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 be reminded to 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 notice any 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 experiencing vomiting. It is essential to instruct patients or caregivers on how to monitor for signs of hypoglycemia effectively.

Storage and Handling

The product is supplied in accordance with the National Drug Code (NDC) specifications. It should be stored at a controlled room temperature of 20°-25°C (68°-77°F), as defined by the United States Pharmacopeia (USP) guidelines. Proper storage conditions are essential to maintain the integrity and efficacy of the product.

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 promptly. No further information is available regarding laboratory tests, abuse potential, route, method, frequency of administration, or postmarketing experience.

FDA Insert (PDF)

This document is the official FDA-approved prescribing information for Metoprolol Succinate as submitted by Dr. Reddy's Laboratories Limited. It includes detailed information about indications, dosage, contraindications, warnings, and clinical pharmacology.

View full prescribing information (PDF)