The nonselective beta blocker alprenolol was developed in the late 1960s and is no longer on the market today. The drug is called nonselective because it does not act in the body exclusively on the ß-adrenoreceptors, which are directly responsible for controlling the heartbeat, but on all three known subsets of the receptors that perform various functions in the body.
What is alprenolol
The nonselective beta blocker alprenolol was developed in the late 1960s and is no longer on the market. Alprenolol is a beta-blocker that was patented and marketed in 1969 by the pharmaceutical company AB Hässle. The drug, which was mainly prescribed for the treatment of high blood pressure, is no longer on the market. The chemical structure of alprenolol is similar to that of oxprenolol, which is why it also belongs to the group of non-selective beta-blockers. If alprenolol is administered in high doses, it has a stabilizing effect on the cell membrane; here, too, alprenolol is similar to the active ingredient oxprenolol. The active ingredient is only partially fat-soluble and has a plasma half-life of up to three hours after administration. However, the bioavailability of alprenolol is relatively low at ten percent. Bioavailability refers to the value at which a compound is available unchanged in the circulation.
Pharmacologic effect
Like all beta-blockers, alprenolol serves to inhibit the excitatory effects of the hormones epinephrine and norepinephrine. However, because alprenolol does not specifically and exclusively target the ß1 receptors that both cardiac output and heart rate directly control, alprenolol is referred to as a nonselective beta blocker. Rather, alprenolol acts on all three subtypes of ß-adrenoceptors, which are found in very high density in the heart, adipose tissue, and smooth muscle. All ß-receptors are stimulated by adrenaline. This is produced in the adrenal medulla and is known as the stress hormone, which is secreted in increased quantities during particular stresses and stressful situations. The consequences of this hormone release are an increase in heart rate, an increase in blood pressure, a widening of the bronchial tubes and an accelerated breakdown of fat in order to provide the body with energy. The cardiovascular system in particular is stressed by this mechanism, which played a vital role in survival in the early days of human development. Beta-blockers such as alprenolol thus block the causes of high blood pressure and a rapid heart rate at the biochemical level.
Medical application and use
Beta-blockers such as alprenolol are prescribed mainly for chronically elevated blood pressure. Hypertension is said to occur when the systolic blood pressure is permanently above a value of 140 mmHg, and the limit for diastolic blood pressure is 90 mmHg. The most common causes of high blood pressure are disorders of the cardiovascular system, the endocrine system and damage to the kidneys. Genetic factors can also play a role. For example, the risk of children suffering from high blood pressure one day increases significantly if this was already the case with their parents. Alongside diabetes and obesity, high blood pressure is an important risk factor for the development of arteriosclerosis, which in turn can cause serious damage to the cardiovascular system, such as heart attacks. Other conditions for which preparations such as alprenolol are administered include coronary heart disease, myocardial infarction therapy, heart failure and cardiac arrhythmias. In addition, there are a number of other conditions, such as hyperthyroidism, anxiety or migraine, for which the preparation can provide relief in individual cases.
Risks and side effects
The active ingredient group ISA contained in alprenolol causes sleep disturbances more frequently than ISA-free beta blockers. Otherwise, the same side effects can occur when taking alprenolol as with all beta blockers. The most common side effects include a pulse that is too slow, heart failure, or asthma attacks. This side effect is also the reason why alprenolol should not be administered to patients suffering from bronchial asthma.Heart failure, which is known as a disease in its own right, refers to the inability of the heart muscle to transport the amount of blood the body needs to the atria without a rise in pressure. Other problems such as fatigue, peripheral circulation problems, depressive moods, or erectile dysfunction can often occur. Cardiac conduction disorders can also occur as an adverse effect of beta-blockers. This is a relatively common form of cardiac arrhythmia.
