Metoprolol vs. losartan

• Metoprolol and losartan are used to treat high blood pressure (hypertension).
• Metoprolol is also used to treat heart pain (angina), congestive heart failure, hyperthyroidism, abnormal heart rhythms, some neurologic conditions, and to prevent migraine headaches.
• Brand names for metoprolol include Lopressor and Toprol XL.
• A brand name for losartan is Cozaar.
• Metoprolol and losartan belong to different drug classes. Metoprolol is a beta-blocker (beta-adrenergic blocking agent) and losartan is an angiotensin receptor blocker (ARB).
• Side effects of metoprolol and losartan that are similar include diarrhea, fatigue, insomnia, and impotence.
• Side effects of metoprolol that are different from losartan include abdominal cramps, constipation, indigestion, nausea, depression, dreaming, memory loss, fever, lightheadedness, low blood pressure, decreased exercise tolerance, increased triglycerides, bronchospasm, cold extremities, sore throat, shortness of breath, or wheezing.
• Side effects of losartan that are different from metoprolol include chest pain, dizziness, low blood sugar (hypoglycemia), muscle cramps, nasal congestion, urinary tract infection (UTI), weakness, persistent cough, and increased blood potassium (hyperkalemia).

Metoprolol is a beta-adrenergic blocking agent (beta-blocker) that works by blocking the action of the sympathetic nervous system (part of the involuntary nervous system). Metoprolol is used to treat high blood pressure (hypertension), heart pain (angina), congestive heart failure, hyperthyroidism, abnormal heart rhythms, some neurologic conditions, and to prevent migraine headaches.

Losartan is an angiotensin receptor blocker (ARB) used to treat high blood pressure (hypertension), reducing the risk of stroke in patients with hypertension, and left ventricular hypertrophy (overdeveloped heart muscle). Losartan is also used to treat people with type 2 diabetes and hypertensive patients with diabetic nephropathy (kidney disease). Angiotensin formed in the blood is a chemical that attaches to angiotensin receptors found primarily on smooth muscle cells of blood vessels. Angiotensin's attachment to the receptors causes the muscle cells to contract and the blood vessels to narrow, which leads to high blood pressure (hypertension). Losartan works to block the angiotensin receptor, which relaxes muscle cells and dilates blood vessels, thereby reducing blood pressure.

Metoprolol

Metoprolol is generally well tolerated. Side effects include:

• Abdominal cramps
• Diarrhea
• Constipation
• Fatigue
• Insomnia
• Indigestion
• Nausea
• Depression
• Dreaming
• Memory loss
• Fever
• Impotence
• Lightheadedness
• Low blood pressure
• Decreased exercise tolerance
• Increased triglycerides
• Bronchospasm
• Cold extremities
• Sore throat
• Shortness of breath or wheezing

Possible serious adverse effects include:

• Slow heart rate
• Raynaud's phenomenon
• Hepatitis
• Increased insulin resistance

Metoprolol can aggravate breathing difficulties in patients with asthma, chronic bronchitis, or emphysema.

WARNING:

• 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.

Losartan

Side effects include:

• Chest pain
• Diarrhea
• Dizziness
• Fatigue
• Insomnia
• Low blood sugar (hypoglycemia)
• Muscle cramps
• Nasal congestion
• Urinary tract infections (UTIs)
• Weakness

Losartan also may cause:

• A persistent cough
• An increase serum potassium (hyperkalemia)
• Impotence (erectile dysfunction, ED)

Losartan may reduce kidney function in some patients and should not be used by patients who have bilateral renal artery stenosis (narrowing of both arteries going to the kidneys).

Rare cases of rhabdomyolysis (muscle breakdown) have been reported.

Metoprolol

• 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.

Losartan

• The starting dose of losartan for adults is 25 to 50 mg daily.
• The maximum dose is 100 mg daily. The total daily dose of losartan may be divided and administered twice daily.
• The starting dose of losartan for pediatric patients 6 years of age or older is 0.7 mg/kg up to 50 mg once daily. Doses more than 1.4 mg/kg or 100 mg daily have not been
• Losartan may be given with or without food.evaluated in pediatric patients.

Metoprolol

• 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.

Losartan

• The starting dose of losartan for adults is 25 to 50 mg daily.
• The maximum dose is 100 mg daily. The total daily dose of losartan may be divided and administered twice daily.
• The starting dose of losartan for pediatric patients 6 years of age or older is 0.7 mg/kg up to 50 mg once daily. Doses more than 1.4 mg/kg or 100 mg daily have not been evaluated in pediatric patients.
• Losartan may be given with or without food.

Metoprolol

• 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.

Losartan

Losartan may increase levels of blood potassium (hyperkalemia), which can lead to serious heart problems (arrhythmias). Therefore, concomitant use of other drugs or substances that increase blood -- such as potassium-sparing diuretics (for example, spironolactone [Aldactone], triamterene, and amiloride), potassium supplements, or salt substitutes containing potassium -- may lead to dangerous increases in serum potassium.

Combining losartan or other ARBs with nonsteroidal anti-inflammatory drugs (NSAIDs) in patients who are elderly, fluid-depleted (including those on diuretic therapy), or with poor kidney function may result in reduced kidney function, including kidney failure. These effects usually are reversible.

The antihypertensive effect of losartan may be reduced by aspirin and other NSAIDs such as:

• ibuprofen (Advil, Children's Advil/Motrin, Medipren, Motrin, Nuprin, PediaCare Fever, etc.)
• indomethacin (Indocin, Indocin-SR)
• naproxen (Anaprox, Naprelan, Naprosyn, Aleve)

Combining ARBs, ACE inhibitors, or aliskiren (Tekturna) increases risk of hypotension (low blood pressure), hyperkalemia, and reduces kidney function compared to each drug used alone, and there is no additional benefit on preventing end stage kidney disease or death.

Aliskiren and losartan should not be combined in patients with diabetes or with renal impairment.

Increases in blood lithium (Eskalith, Lithobid) levels and lithium toxicity have occurred when lithium and ARBs or hydrochlorothiazide were combined. Blood lithium levels should be monitored.

Metoprolol

• 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.

Losartan

When used in the second or third trimester of pregnancy, ARBs can cause injury and even death to the fetus. Losartan should not be used during pregnancy. When pregnancy is first detected, losartan should be stopped.

It is not known whether losartan is excreted in breast milk, but losartan and its active form are excreted in rat milk. Due to the possibility of harm to the nursing infant, if possible, losartan should be discontinued by females who are nursing.