What is metoprolol?
Metoprolol is a beta-blocker medication that affects the heart and blood circulation [1]. Specifically, it is a cardio-selective beta-1-adrenergic receptor blocker [2]. This means that metoprolol targets only the heart.
The most common uses of metoprolol are treating high blood pressure and preventing cardiac-related chest pain (angina) [3]. However, it is also given to people suffering from heart failure and heart attacks [1].
Metoprolol’s action is a reduction of the heart rate and heart contraction force [2].
Among the side effects of the drug are:
- dizziness [1],
- insomnia [1],
- fatigue [1],
- diarrhea [1],
- depression [1],
- confusion [1],
- rash [1],
- slow heart rate [1],
- shortness of breath [1],
- fast weight gain[1],
- cold extremities [1],
- low blood pressure [3].
Among other unwanted effects of metoprolol are metabolic changes seen in increased blood glucose and triglyceride levels [4].
Metoprolol is available in fast- or slow-release forms and can be taken orally or given as an injection [5, 6].
What is metoprolol withdrawal syndrome?
Withdrawal syndrome can occur from 36h to 3 days after abrupt discontinuation of metoprolol [7].
Characteristics of the metoprolol withdrawal syndrome are:
- fast increase in heart rate (tachycardia)[2],
- increase in blood pressure [2],
- worsening of angina [2],
- confusion [8],
- depression [8].
In severe situations, metoprolol withdrawal syndrome can even lead to a heart attack [2]. It occurs due to an abrupt reduction of the blood flow in the heart, leading to a deficit of oxygen. Some cases of metoprolol withdrawal require getting back to the medication to mitigate the symptoms.
How does metoprolol cause withdrawal syndrome?
One of the main problems in metoprolol withdrawal syndrome is the fast heartbeat. It occurs due to the high sensitivity of the heart to the natural stimulation of epinephrine. The heart overreacts to the simulation meant to only slightly increase its rate [9, 10].
The mechanism of the increase in blood pressure is also based on the problem with epinephrine. In the circulatory system, the blood vessels constrict, decreasing the space for the blood and raising its pressure [9].
Also, the potential worsening of cardiac-related chest pain, called angina, has a similar etiology. After the discontinuation of metoprolol, the heart rate and oxygen demand in the heart increase [11].
Patients with coronary atherosclerosis have a local heart artery obstruction that limits the blood and oxygen supply to certain heart areas. Therefore, during metoprolol withdrawal syndrome, when the oxygen demand is higher and some parts of the heart do not receive enough blood, it can lead to angina.
How to prevent metoprolol withdrawal syndrome?
The primary step in the prevention of metoprolol withdrawal syndrome is taking and getting the medication under a healthcare professional’s guidance [1].
Any abrupt discontinuation of metoprolol must be avoided. Typically, upon therapy completion, doctors gradually reduce the dosing. It takes up to two weeks for metoprolol to taper. It is crucial in withdrawal syndrome prevention [12].
It is also important to regularly see your doctor during and after the therapy. That way, if you experience any symptoms, you can report them to the physician [13]. It can also help to act against any withdrawal symptoms before they become stronger.
In some cases, taking other drugs can prevent the withdrawal syndrome. For example, taking medications like calcium antagonists can help in the prevention of withdrawal syndrome after beta-blockers [14].