Bisoprolol is a medication and is used to treat tachycardia, angina, hypertension, and coronary artery disease (CAD). Bisoprolol has an antagonistic effect on ß-adrenoreceptors (beta-adrenoreceptors) and belongs to the group of beta-blockers. Taking the drug can cause side effects such as fatigue, dizziness, and headache.
What is bisoprolol?
Bisoprolol belongs to the group of selective ß-adrenoreceptor blockers and has an antagonistic effect on ß1-adrenoreceptors. As a selective beta-blocker, bisoprolol acts specifically on the heart and has no effect on other organs. Medically, bisoprolol is referred to as a cardioselective drug. Chemically, bisoprolol is a phenolic ether that exists as a racemic mixture. Bisoprolol is a chiral compound and the drug is used in a 1:1 mixture of the stereoisomers (R) and (S). The (S) form of the drug is the active stereoisomer and has a high binding affinity to ß1-adrenoreceptors. (S)-Bisoprolol displaces epinephrine from the binding site of the ß1-adrenoreceptor and acts as an antagonist. The drug is used to treat angina pectoris, tachycardia, chronic heart failure and hypertension. The drug needs to be taken regularly. Sudden cessation of therapy leads to withdrawal symptoms and serious side effects.
Pharmacologic effects on the body and organs
The beta-blocker bisoprolol occupies ß1-adrenoreceptors and prevents epinephrine and norepinephrine from binding to the receptors. Norepinephrine is a neurotransmitter that is produced in the brain as well as in the adrenal cortex in humans. Adrenaline is a hormone produced in the adrenal cortex of humans. Adrenaline and noradrenaline differ in chemical structure by a methyl group. In epinephrine, a methyl group is substituted for the amino group. Norepinephrine and epinephrine bind to ß1-adrenoreceptors in the heart and lead to increased activity of the heart muscle. Heart rate increases due to lowering of the threshold of stimulation in the heart. The pumping action of the heart is increased and blood pressure is raised. Bisoprolol displaces epinephrine and norepinephrine from the ß1-adrenoreceptors and occupies the binding sites. As an antagonist, the drug attenuates the effects of epinephrine and norepinephrine. As a result of receptor binding and decreased epinephrine and norepinephrine action, blood pressure is lowered and the threshold of irritability is raised. The heart requires less energy and oxygen consumption is reduced. Overall, the heart muscle is relieved by bisoprolol. In medicine, this is referred to as a negative inotropic effect, which all beta-blockers possess. The binding and effect of bisoprolol are long-lasting. The half-life in the blood is 10 to 11 hours. Bisoprolol is administered orally and is approximately 90% absorbed. Bioavailability is excellent at 90% and maximum plasma concentration is reached approximately 3 hours after ingestion. The beta-blocker is excreted renally and metabolized in the liver. The ratio of renal excretion to hepatic elimination is 50:50. Because of bisoprolol’s targeting of the ß1-adrenoreceptor, the drug has a cardiospecific effect. Nevertheless, central nervous effects may occur. Effects as well as side effects by bisoprolol on the central nervous system (CNS) are due to the lipophilic properties of the drug. Intrinsic sympathomimetic activity (ISA) has not been demonstrated.
Medical application and use for treatment and prevention.
The beta-blocker bisoprolol is used to treat arterial hypertension (high blood pressure), chronic heart failure, angina pectoris, and tachycardia. Angina pectoris can be triggered by coronary heart disease (CHD). The beta-blocker is often used for hypertension and thus serves to prevent severe heart disease. Treatment of arterial hypertension as well as angina pectoris is usually started with a dose of 5 mg bisoprolol per day. The dose depends on the severity of the findings. For mild hypertension, a daily dose of 2.5 mg is recommended. If a dose of 5 mg bisoprolol is not sufficient, an increase to 10 mg bisoprolol per day is recommended. Only in exceptional cases should the daily dose be above 10 mg. The dosage should be gradually increased or slowly decreased as needed.If the drug is suddenly discontinued, withdrawal symptoms and severe side effects are the result. Discontinuation of bisoprolol is only possible by tapering and must be accompanied by a physician. Bisoprolol must not be used in patients with bronchial asthma, bradycardia, diabetes mellitus, and severe heart failure. Patients applying MAO inhibitors should also refrain from taking the drug.
Risks and Side Effects
Taking bisoprolol may cause side effects. Common complaints include fatigue, tiredness, sensory disturbances, dizziness, and headache. Occasional side effects of the drug include depression, sleep disturbances, mood changes, and confusion. Furthermore, taking the drug may cause circulatory disorders, muscle weakness, skin rashes, joint disorders, and skin itching. Disturbed heart function and a slowed heartbeat are also part of the symptoms. A drop in blood pressure due to standing up quickly from a sitting or lying position is also among the occasional side effects. Vomiting, constipation, diarrhea, abdominal pain and nausea are also occasional gastrointestinal side effects. Rarely, reactions such as increased blood lipids, increased sweating, decreased lacrimation, weight gain, and sexual listlessness occur.
