From the Guidelines
Metoprolol should not be used as needed (PRN) due to the risk of rebound effects and the importance of maintaining consistent blood levels to effectively control conditions like hypertension, angina, and heart failure. The most recent and highest quality study, 1, suggests that beta blockers, including metoprolol, should be started early in the absence of contraindications and taken regularly to maintain steady blood levels. Taking metoprolol irregularly or only when symptoms occur can lead to fluctuating blood pressure and heart rate, potentially causing rebound effects when the medication wears off. These rebound effects can include increased heart rate, blood pressure spikes, or worsened chest pain, which could be dangerous.
Key Points to Consider
- Metoprolol is a beta-blocker medication that works best when taken consistently to maintain steady blood levels in the body.
- The medication is designed to control conditions like hypertension, angina, and heart failure by consistently blocking certain receptors in the heart and blood vessels.
- Taking metoprolol irregularly or only when symptoms occur can lead to rebound effects, including increased heart rate, blood pressure spikes, or worsened chest pain.
- For most patients, metoprolol should be taken regularly as prescribed, usually once or twice daily depending on the formulation (immediate-release or extended-release).
- If symptoms occur that make you feel you need additional medication, it's essential to consult with your healthcare provider to adjust your regular dosing regimen rather than using metoprolol on an as-needed basis.
Recommendations Based on the Evidence
- Metoprolol should be taken regularly as prescribed, rather than on an as-needed basis, to maintain consistent blood levels and effectively control conditions like hypertension, angina, and heart failure.
- Consult with your healthcare provider if you're experiencing symptoms that make you feel you need additional medication, rather than using metoprolol on an as-needed basis.
- Be aware of the potential rebound effects of taking metoprolol irregularly, including increased heart rate, blood pressure spikes, or worsened chest pain.
From the Research
Metoprolol Usage
- Metoprolol is a beta1-selective adrenoceptor blocking drug, commonly used in the treatment of mild to moderate hypertension and angina pectoris 2, 3.
- The drug has been shown to be effective in reducing angina frequency and improving exercise tolerance in patients with uncomplicated angina pectoris 4.
- Controlled release metoprolol formulations have been developed to provide sustained and consistent metoprolol plasma concentrations and beta 1-blockade, allowing for once daily administration 5.
Administration Frequency
- Metoprolol can be administered twice daily, but satisfactory control can be maintained in many patients with single daily doses of conventional or slow release formulations 2.
- Once daily administration of metoprolol has been shown to be effective in reducing blood pressure and angina attacks in patients with mild to moderate hypertension and stable effort angina pectoris 5, 6.
- There is no evidence to suggest that metoprolol should be used as needed (prn, pro re nata), as its effectiveness is based on regular administration to maintain therapeutic plasma concentrations 2, 3, 4, 5, 6.
Efficacy and Safety
- Metoprolol has been shown to be effective in reducing angina attacks and improving exercise tolerance in patients with angina pectoris, with a similar or higher response rate compared to other beta-blockers 4, 6.
- The drug is generally well tolerated, with temporary fatigue, dizziness, and headache being among the most frequently reported side effects 2, 6.
- Controlled release metoprolol formulations have been associated with a similar or lesser degree of adverse effects related to the central nervous system compared to other beta-blockers 5.