Metoprolol vs. diltiazem: What’s the difference?
- Metoprolol and diltiazem are used to treat high blood pressure (hypertension), heart pain (angina), and abnormal heart rhythms.
- Metoprolol is also used to treat congestive heart failure, hyperthyroidism, and some neurologic conditions, and to prevent migraine headaches.
- Brand names for metoprolol include Lopressor and Toprol XL.
- Brand names for diltiazem include Cardizem, Cardizem CD, Cardizem LA, Tiazac, Cartia XT, Diltzac, and Dilt-CD.
- Metoprolol and diltiazem belong to different drug classes. Metoprolol is a beta-blocker (beta-adrenergic blocking agent) and diltiazem is a calcium channel blocker (CCB).
- Side effects of metoprolol and diltiazem that are similar include constipation, nausea, and low blood pressure (hypotension).
- Side effects of metoprolol that are different from diltiazem include abdominal cramps, diarrhea, fatigue, insomnia, indigestion, depression, dreaming, memory loss, fever, impotence, lightheadedness, decreased exercise tolerance, increased triglycerides, bronchospasm, cold extremities, sore throat, shortness of breath, or wheezing.
- Side effects of diltiazem that are different from metoprolol include headache, rash, swelling of the legs and feet with fluid (edema), drowsiness, dizziness, liver dysfunction, overgrowth of the gums, and mildly abnormal liver tests.
What are metoprolol and diltiazem?
Metoprolol is a beta-adrenergic blocking agent (beta-blocker) that blocks the action of the sympathetic nervous system (a portion of the involuntary nervous system). Metoprolol is used to treat high blood pressure (hypertension), heart pain (angina), congestive heart failure, abnormal heart rhythms, hyperthyroidism, some neurologic conditions, and to prevent migraine headaches.
Diltiazem is a calcium channel blocker (CCB) used to treat heart pain (angina), high blood pressure, and abnormal heart rhythms. CCBs block the entry of calcium into muscle cells that make up the heart and surround the arteries. Calcium entering these cells causes them to contract, allowing the heart to pump blood, and the arteries to narrow. By blocking the entry of calcium, diltiazem decreases the force of contraction of the heart and its rate of contraction. It also relaxes the muscles surrounding the arteries, allowing the arteries to widen (dilate). By dilating arteries, diltiazem reduces the pressure in the arteries into which the heart must pump blood, so the heart needs to work less and requires less oxygen. By reducing the heart's need for oxygen, diltiazem relieves or prevents angina. Dilation of the arteries also reduces blood pressure.
Salt and sodium are the same.
What are the side effects of metoprolol and diltiazem?
Metoprolol is generally well tolerated. Side effects include:
- Abdominal cramps
- Memory loss
- Low blood pressure
- Decreased exercise tolerance
- Increased triglycerides
- Cold extremities
- Sore throat
- Shortness of breath or wheezing
Possible serious adverse effects include:
- In patients with existing slow heart rates (bradycardias) and heart blocks (defects in the electrical conduction of the heart), metoprolol can cause dangerously slow heart rates, and even shock. Metoprolol reduces the force of heart muscle contraction and can aggravate symptoms of heart failure. In patients with coronary artery disease, abruptly stopping metoprolol can suddenly worsen angina, and occasionally precipitate heart attacks. If it is necessary to discontinue metoprolol, its dosage should be reduced gradually over several weeks.
- Initiation of high-dose extended release metoprolol in patients undergoing non-cardiac surgery is associated with bradycardia (slow heart rate), hypotension, stroke, and death. However, long-term therapy with metoprolol should not be routinely withdrawn prior to major surgery. Impaired ability of the heart to respond to reflex adrenergic stimuli may increase the risks of general anesthesia and surgery.
Side effects include:
- Edema (swelling of the legs and feet with fluid)
- Low blood pressure (hypotension)
Liver dysfunction and overgrowth of the gums also may occur. Diltiazem can cause mildly abnormal liver tests that usually return to normal with discontinuation of the medication. When diltiazem is given to individuals with heart failure, symptoms of heart failure may worsen because these drugs reduce the ability of the heart to pump blood. Like other drugs for high blood pressure, diltiazem is associated with sexual dysfunction.
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What is the dosage of metoprolol vs. diltiazem?
- Metoprolol should be taken before meals or at bedtime.
- The dose for treating hypertension is 100 to 450 mg daily in single or divided doses.
- Angina is treated with 100 to 400 mg daily in two divided doses.
- Heart attack (acute myocardial infarction) is treated with three 5 mg injections administered 2 minutes apart followed by treatment with 50 mg oral metoprolol every 6 hours for 48 hours. After 48 hours, patients should receive 100 mg orally twice daily for at least 3 months.
- The dose for congestive heart failure is 25 mg/daily initially. Then the dose is increased every 2 weeks to reach a target dose of 200 mg/daily orally.
- Hyperthyroidism is treated with 25 to 30 mg by mouth every 6 hours.
- Adult oral doses for chest pain or high blood pressure (hypertension) range between 120 and 540 mg daily. Dosing varies depending on formulation and use.
- Immediate release tablets are administered up to 4 times a day.
- Extended release formulations are administered once daily at approximately the same time each day and should not be crushed or chewed.
- Injectable forms are used for treating atrial fibrillation, atrial flutter and paroxysmal supraventricular tachycardia.
What drugs interact with metoprolol and diltiazem?
- Calcium channel blockers and digoxin (Lanoxin) can lower blood pressure and heart rate to dangerous levels when administered together with metoprolol.
- Metoprolol can mask the early warning symptoms of low blood sugar (hypoglycemia) and should be used with caution in patients receiving treatment for diabetes.
- Fluoxetine (Prozac) can increase blood levels of metoprolol by reducing breakdown of metoprolol, and increase the side effects from metoprolol.
- Administration of diltiazem with digoxin (Lanoxin) can increase digoxin blood levels. Therefore, blood levels of digoxin usually are monitored to avoid toxicity from digoxin.
- Similarly, concurrent administration of diltiazem with an anti-seizure medication, carbamazepine (Tegretol), can increase blood levels of the seizure medication, and occasionally lead to toxicity.
- Diltiazem increases blood levels of lovastatin (Mevacor), atorvastatin (Lipitor), and simvastatin (Zocor), possibly increasing the risk of adverse effects.
- Diltiazem may increase blood levels of buspirone (Buspar), midazolam (Versed), triazolam (Halcion), and diazepam (Valium) by reducing the liver's ability to break down and eliminate these drugs from the body, which can lead to toxicity.
- Rifampin (Rifamate, Rifadin, Rimactane) reduces the effect of diltiazem by reducing its blood levels to undetectable levels.
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Are metoprolol and diltiazem safe to use while pregnant or breastfeeding?
- Safe use of metoprolol during pregnancy has not been established.
- Small quantities of metoprolol are excreted in breast milk and may potentially cause adverse effects in the infant.
Diltiazem is excreted in breast milk. To avoid adverse effects in the infant, diltiazem should not be taken while nursing.