Metoprolol - Use | Dose | Side Effects
Metoprolol is a drug from the group of selective beta-1 blockers. It is the first choice drug in the treatment of mild to moderate hypertension and stable angina pectoris.1 Metoprolol is also used for:
- Treatment of complex ventricular tachycardia2
- Symptoms relief in patients with overactive thyroid gland3
- Migraine prophylaxis4
- Prevention of heart muscle damage in patients after myocardial infarctions
Contraindications and precautions
Contraindications for Metoprolol use are the following:
- Peripheral vascular diseases5
- Metabolic acidosis
- Second or third degree heart block
Metoprolol should be administered cautiously in the following situations:
- First-degree heart block
- Prinzmetal's angina
- Chronic obstructive pulmonary disease
- Liver disease
There have been reports of visual hallucinations in patients taking this drug.7 If you notice this side effect, you should contact your doctor.
Metoprolol, pregnancy and breastfeeding
Some studies suggest that Metoprolol is more efficient than Methyldopa for blood pressure control and that it has a lower risk of causing malformations and other adverse effects in fetus.8 According to the FDA, Metoprolol is classified in group C, which means that studies in animals have shown adverse effects of this drug on the fetus. For this reason, Metoprolol should be used during pregnancy only when necessary. The pharmacokinetics of this drug is significantly changed during pregnancy and your doctor will determine whether you can take this drug and what dose you should take if you are pregnant or breastfeeding.
Metoprolol is excreted into breast milk in low concentrations and adverse effects on infants whose mothers took this drug have not been observed. Consult your doctor before you start taking Metoprolol during breastfeeding.
The recommended dosage is given in the table below:
|Hypertension||Starting dose: 50 mg two times a day or 100 mg once a day. Maintenance dose: 100-200 mg daily, divided into two doses|
|Stable angina pectoris||Startign dose: 50 mg two times a day or 100 mg once a day. Maintenance dose: 100-200 mg daily, divided into two doses. If needed, dose may be increased up to 300 mg.|
|Ventricular arrhythmias||100-200 mg daily, divided into two doses|
|Hyperthyroidism||50 mg four times a day|
|Migraine prevention||100-200 mg daily, divided into two doses|
Take the tablet on an empty stomach with 200 ml of water.
Metoprolol can interact with the following medications:
- Antidepressants (paroxetine, fluoxetine, and bupropion). Concomitant use of Metoprolol with these drugs increases the risk of serious side effects. Instead of these antidepressants, studies have shown that Metoprolol can be safely used concurrently with the following antidepressants: sertraline, venlafaxine and mirtazapine.9
- Propafenone (antiarrhythmic). It is necessary to reduce the dose of Metoprolol when administered concurrently with propafenone.10
- Theophylline (a drug used to treat asthma). Co-administration of these drugs leads to reduced effectiveness of Metoprolol.
- Antagonists of 5-HT3 receptors (e.g. dolasetron), which are used to treat chemotherapy-induced nausea. Co-administration of these drugs with Metoprolol increases the risk of arrhythmia.
- Atazanavir and atazanavir-cobicistat. Concomitant administration of Metoprolol with these drugs increases the risk of arrhythmia.
- Calcium blockers (e.g. verapamil, diltiazem, nifedipine and nicardipine). Concomitant use of Metoprolol with these drugs increase the risk of bradycardia.
Metoprolol does not enter into significant interactions with bromazepam and lorazepam.11
Metoprolol may cause the following undesirable effects:
|Very common||Common||Uncommon||Rare||Very rare|
|Fatigue||Dizziness||Depression||Reyn's syndrome||Visual hallucinations|
|Headache||Insomnia||Visual impairment||Ringing in the ears|
|Palpitations||Muscle cramps||Dry mouth||Confusion|
|Shortness of breath||Difficult concentrating||Hair loss||Photosensitivity|
|Cold hands and feet||Choking feeling||Impotence||Arthralgia|
|Abdominal pain||Paresthesia||Hepatic impairment||Thrombocytopenia|
|Diarrhea or constipation||Weight gain||Anxiety||Taste disorders|