Based on the pathogenesis of bronchial asthma, bronchodilators and anti-inflammatory drugs are used in the fight against asthmatic manifestations .
Adrenomimetics for bronchial asthma quickly relieve the symptoms of suffocation. It should be remembered that all bronchodilators are symptomatic.
How often they are used will be an indicator of the effectiveness of the basic, basic therapy.
Mechanism of action of adrenergic agonists
So, adrenergic agonists are an extensive group of drugs that have a stimulating effect on adrenergic receptors . Adrenergic receptors are localized in all tissues of the body – they are built into cell membranes, they are special protein molecules.
The effect of adrenergic agonists is determined by the effect on receptors, which leads to certain metabolic changes. As a result, spasm or vasodilatation may occur, etc.
Adrenomimetics have a stimulating effect on adrenergic receptors , similar to the action of adrenaline and norepinephrine. When an agonist molecule binds to a receptor on the cell’s surface, it interacts with a regulatory protein.
This protein contributes to the activation of a special enzyme that stimulates the synthesis of adenosine monophosphate , a substance involved in signaling in the cell. As a result, certain chemical processes occur in the cell, as a result of which the concentration of calcium changes.
The smooth muscles of various organs react to this process by relaxing or contracting.
The effect of drugs depends on the type of receptors that are affected.
Although there are 5 types of adrenergic receptors , we will focus only on beta1- and beta2-adrenergic receptors, since we are talking about asthma.
So, beta1-adrenergic receptors are localized in the heart, and their stimulation leads to an increase in heart rate, an increase in blood pressure. They are also found in the kidneys.
Beta-2-adrenergic receptors are localized in the bronchi, skeletal muscles, blood vessels, heart and other organs. The effect of their stimulation will be to relax the smooth muscles of the bronchi, relieve spasm, and expand the lumen of the bronchial tree.
In asthma, adrenergic agonists have a symptomatic effect and are used to relieve and prevent attacks.
Classification of adrenergic agonists
Adrenomimetics used in bronchial asthma are divided into selective and non-selective. The former are characterized by the fact that they act only on beta2 receptors, and the latter on both beta1 and beta2.
In bronchial asthma, beta-agonists must act on bronchial beta2-receptors. Beta2-adrenergic agonists are long-acting and short-acting. The former have a prolonged effect and help prevent nighttime attacks, while the latter are used as a remedy against exacerbation of asthma.
It should be noted that adrenergic agonists , whether selective or non-selective, are used only as directed by a doctor. If we are talking about short-acting adrenergic agonists, then these are emergency drugs that in no case should be used uncontrollably.
They give a good therapeutic effect, however, they can cause side effects – arrhythmia, hypertensive crisis or hypotension, and much more. Patients with diabetes mellitus, arterial hypertension, atherosclerosis of the cerebral vessels, diseases of the thyroid gland are recommended to use such drugs with caution, in the dose and with the frequency determined by the doctor.
Selective adrenomimetics for bronchial asthma
Beta- adrenomimetics for bronchial asthma are used both selective and non-selective. Selective short-acting adrenomimetics are prescribed in the form of an aerosol, which allows you to quickly relieve the symptoms of bronchial asthma.
If a child cannot use an inhaler due to age, special devices are used to spray a medicinal solution – nebulizers. Doses of drugs for inhalation with a nebulizer are higher.
In large doses, they can activate beta1-adrenergic receptors, alpha- adrenergic receptors in the vessels. Nonselective excite these receptors at any dose. Side effects are associated with this – an increase in blood pressure, an increase in heart rate.
Some selective beta- adrenergic receptor antagonists :
As noted above, beta- adrenergic agents for bronchial asthma are used in combination with glucocorticoids and other agents. Long-acting drugs include, for example, formoterol .
The long-term effect is associated with the accumulation of the substance in the membranes of smooth muscle cells. When combined with glucocorticoids, they enhance the effect of hormones, reduce their dosage and, accordingly, reduce side effects when used to prevent nighttime attacks, as well as manifestations of physical stress asthma.
These drugs cannot be used for monotherapy and as an emergency remedy for choking control. You should also avoid abrupt withdrawal of such drugs.
When applying the optimum dose agonists short-acting beta1-adrenoceptors are stimulated myocardium practically.
This group includes the following drugs:
With an attack of suffocation, short-acting adrenomimetics quickly stop the exacerbation – with inhalation, the effect is observed after four minutes and lasts for several hours. They are also used to prevent physical exertion asthma.
Drugs in this group are not suitable for preventive treatment – these are emergency drugs that work for a short time. Their effectiveness may decrease with frequent use. Regular use of salbutamol leads to increased frequency of physical exertion asthma attacks and increases the severity of inflammation.
Appropriate skills are required for the correct administration of medication using an inhaler. Otherwise, less medicine will enter the bronchial tree than required.
Non-selective adrenomimetics in bronchial asthma
Stimulate beta1-, beta2-, alpha-adrenergic receptors. In bronchial asthma, the following non-selective adrenomimetics are used :
As noted above, non-selective adrenomimetics have an active effect on the cardiovascular system even in small doses, provoke an increase in blood pressure.
It is important that in order to maintain a normal quality of life, a stepwise approach to the use of drugs is optimal, which involves increasing doses and increasing the number of doses as the disease worsens. The main goal is to control asthma by taking minimal doses of medication.
If the patient’s condition worsens, the dose and frequency of administration increases. If asthma is well controlled, then the dose and frequency of administration is reduced. To move from one stage to another, it is necessary to control the disease well for a certain time.
The goal of treatment is to maintain a normal quality of life, to maintain the usual physical activity.
The prognosis of bronchial asthma largely depends on whether the patient complies with all the prescriptions that relate to both the drug intake regimen and the general rules, knowledge of the differences between drugs of basic and emergency therapy, and preventive measures.
Even during the period of remission, the inflammatory process persists in the airways, but this does not mean that it is impossible to achieve good health. You should not rely only on medicines: it is necessary to exclude contact with allergens, follow elimination diets and, in general, take care of your health.