What type of metoprolol (beta blocker), specifically metoprolol succinate or metoprolol tartrate, is the most cardioselective medication?

From the Guidelines

Metoprolol succinate is the best cardioselective metoprolol option due to its extended-release formulation, which provides more consistent 24-hour blood levels and leads to better blood pressure control and improved patient adherence. Metoprolol tartrate and metoprolol succinate are both cardioselective beta-blockers, but metoprolol succinate is generally considered the better option for cardiovascular conditions 1. The extended-release formulation of metoprolol succinate results in fewer peak-related side effects and maintains more stable beta-blockade throughout the day. For heart failure, hypertension, or post-myocardial infarction treatment, metoprolol succinate is typically preferred at doses ranging from 25-200 mg once daily, depending on the condition and patient response.

• The cardioselectivity of metoprolol means it primarily blocks beta-1 receptors in the heart rather than beta-2 receptors in the lungs, making it safer for patients with respiratory conditions like asthma or COPD, though caution is still warranted.
• This selectivity diminishes at higher doses, so using the lowest effective dose is important to maintain this advantage.
• Bisoprolol and metoprolol succinate are preferred in patients with HFrEF, and abrupt cessation should be avoided 1.
• It is essential to consider the patient's specific condition, response, and potential interactions when selecting a beta-blocker, and metoprolol succinate is often the preferred choice due to its pharmacokinetic profile and clinical efficacy.

From the Research

Metoprolol as a Cardioselective Medication

• Metoprolol is a widely used cardioselective beta-blocker, with its beta 1 blocking activity residing in the S-isomer 2.
• The S-isomer of metoprolol has been shown to be effective and well-tolerated in patients with hypertension, angina, and coexisting conditions such as diabetes, COPD, and hyperlipidaemia 2.
• Clinical experience with chirally pure S-metoprolol has demonstrated its effectiveness at half the dose of the racemate, with reduced risk of side-effects and drug interactions 2.

Comparison with Other Beta-Blockers

• Metoprolol succinate has been shown to be associated with significant mortality and morbidity benefits in the treatment of heart failure, and is considered a useful drug in both heart failure and atrial fibrillation 3.
• The choice of beta-blocker is important, as benefit is not a class-effect, and metoprolol succinate is one of the options for optimal efficacy, along with bisoprolol and carvedilol 4.
• Beta-blockers with proven effects on mortality and sudden cardiac death, such as metoprolol, have been found to have some degree of lipophilicity, which may contribute to their effectiveness 5.

Cardioselectivity and Efficacy

• S-metoprolol has been shown to have higher cardioselectivity in clinical settings, with less interaction potential compared to the R-isomer 2.
• Metoprolol succinate has been found to be effective in reducing new incidents of atrial fibrillation in high-risk patients, and is associated with significant mortality and morbidity benefits in the treatment of heart failure 3.
• The extended-release formulation of metoprolol is considered a suitable pharmacological option in different cardiovascular conditions, including heart failure, ischemic artery disease, arterial hypertension, and atrial fibrillation 6.