Metoprolol Succinate Er 50 Mg Tablet

Metoprolol Succinate ER 50 mg Tablet: Pharmacokinetics, Efficacy, and Bioequivalence

Pharmacokinetics of Metoprolol Succinate ER

Absorption and Time to Maximum Concentration (Tmax)

Metoprolol succinate extended-release (ER) tablets are designed to provide a controlled release of the drug over an extended period. A study comparing brand name and generic formulations of metoprolol ER tablets found that the time to maximum concentration (Tmax) varied significantly between products. The brand name had a Tmax of 6.1 ± 3.6 hours, while two generic formulations had Tmax values of 3.5 ± 4.9 hours and 9.6 ± 3.2 hours, respectively. This variation in Tmax can influence the drug's effects on autonomic balance over the dosing interval.

Bioavailability and Steady-State Plasma Concentrations

The pharmacokinetic properties of a new controlled-release formulation of metoprolol succinate were compared with conventional tablets. The controlled-release formulation showed less variation in plasma concentrations throughout the day, resulting in a more consistent therapeutic effect. This formulation also achieved a higher plasma concentration at the end of the dose interval, indicating better utilization of the drug.

Efficacy and Safety in Clinical Use

Management of Angina and Hypertension

In a clinical study comparing S-metoprolol ER (50 mg) and racemate metoprolol ER (100 mg) in patients with chronic stable angina, both formulations significantly reduced the number of angina attacks and improved blood pressure control. The S-metoprolol group showed a slightly higher response rate in angina relief (72%) compared to the racemate group (62%), although the difference was not statistically significant. Both formulations were well-tolerated, with similar adverse event profiles.

Treatment of Essential Hypertension

A study on the treatment of mild to moderate essential hypertension with metoprolol succinate sustained-release tablets (47.5 mg and 95 mg) demonstrated significant reductions in blood pressure and heart rate over a 4-week period. The sustained-release formulation provided stable blood pressure control over 24 hours, making it an effective option for managing hypertension.

Bioequivalence Studies

Comparison Under Fasting and Fed Conditions

Bioequivalence studies in healthy Chinese subjects under fasting and fed conditions showed that the test metoprolol ER tablet was bioequivalent to the reference tablet (Betaloc ZOK). The 90% confidence intervals for key pharmacokinetic parameters (AUC0-48h, AUC0-inf, and Cmax) were within the acceptable range of 80-125%, indicating that both formulations are interchangeable.

In Vitro Evaluation of Extended Release Matrix Tablets

An in vitro study developed extended-release matrix tablets of metoprolol succinate (25 mg and 50 mg) using various matrixing agents. The drug release profile was comparable to marketed tablets, providing controlled and predictable release over approximately 20 hours. This formulation showed near zero-order release kinetics, governed by diffusion and erosion mechanisms.

Conclusion

Metoprolol succinate ER 50 mg tablets offer a reliable and effective option for managing conditions such as hypertension and angina. The pharmacokinetic properties, including consistent plasma concentrations and controlled release, contribute to their therapeutic efficacy. Bioequivalence studies confirm that generic formulations are comparable to brand-name products, ensuring their interchangeability in clinical practice. Overall, metoprolol succinate ER tablets provide stable and sustained drug release, making them a valuable choice for long-term cardiovascular management.

Summary

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