Notes in the use of bronchodilators
The article was written by Master, Doctor Tran Thi Diem Trang - Department of Examination & Internal Medicine - Vinmec Central Park International General Hospital
Bronchodilators have the effect of relaxing bronchial smooth muscles, thereby increasing the airway diameter, making it easier for air to pass through the airways to reach the alveoli to exchange oxygen and receive carbon dioxide. Bronchodilators have good effects in the treatment of respiratory diseases such as bronchial asthma, chronic obstructive pulmonary disease.
1. Bronchodilator drugs
Bronchodilators have the effect of relaxing the smooth muscle that surrounds the bronchi, thereby helping to dilate the bronchi, increasing the diameter of the airways, so that air can easily pass through the airways to reach the alveoli. responsible for gas exchange for the respiratory system. Bronchodilators currently in use include 3 groups:
Xanthine group bronchodilators: This group of drugs has the active ingredient theophylline, which has been used for a long time, this is a fast-acting, short-acting drug. released as slow release, thus making it easier for the user. Bronchodilators of the beta 2 adrenergic group (including 2 smaller groups: short-acting drugs such as fenoterol, salbutamol, terbutaline; slow-acting and long-acting drugs such as salmeterol, bambuterol, formoterol). Anticholinergic bronchodilators (fast-acting, short-acting: ipratropium bromide, oxitropium bromide; slow-acting, long-acting: tiotropium bromide, aclidinium bromide). Many bronchodilators are produced as single agents; however, some are now manufactured as combinations of two bronchodilators, usually a combination of an anticholinergic and a bronchodilator. beta 2 adrenergic group to increase the bronchodilator effect.
2. In what cases is bronchodilator indicated?
Bronchodilators are generally indicated for cases where bronchospasm causes difficulty breathing for the patient. Diseases commonly prescribed bronchodilators include:
Asthma Chronic obstructive pulmonary disease Bronchiectasis in exacerbation (often with bronchial smooth muscle spasm). Some special cases such as sinus bradycardia In the treatment of bronchial smooth muscle spasms, inhaled, inhaled, aerosol bronchodilators (collectively referred to as aerosol-inhaled drugs) are often preferred. Because the drug is used directly on the airway mucosa, it has a fast, optimal effect and causes few side effects due to the low dose of the drug, besides, the drug is located mainly in the airway mucosa and only penetrates into the bloodstream with very low concentrations. Moreover, the spray-inhaled drugs themselves provide an additional amount of water into the airways, which has the effect of thinning the sputum and facilitating the expectoration of the patient's sputum.
Among bronchodilators, long-acting drugs are often preferred for stable-stage disease. Due to the long-lasting bronchodilator effect of the drug, the patient feels comfortable throughout the day. Short-acting, rapid-acting bronchodilators are often preferred during exacerbations or when the patient has an attack of breathlessness.
In general, bronchodilators are usually prescribed according to the severity of the disease. If you have severe bronchospasm or those with poor response to bronchodilators are often given more bronchodilators at higher doses, while patients with mild disease are often less bronchodilators are used.
3. Side effects when taking bronchodilators
Like all drugs, oral bronchodilators have some side effects. Here are some common side effects:
Beta-2 agonists – common side effects include: tremors (eg, hand tremors), nervous tension, headache, cramps, cold feeling of a fast, irregular heartbeat (palpitations). Methylxanthines – common side effects include: palpitations, feeling sick (nausea), headache, arrhythmia, seizures. Rare side effects: peripheral vasodilatation, cardiac arrhythmias, hypokalemia, increased blood glucose and free fatty acids, hypersensitivity (allergic) reactions. Inhalation may cause bronchospasm. Repeated use will have rapid drug tolerance because the number of beta 2 adrenergic receptors of the bronchi gradually decreases (downregulation mechanism), patients tend to have to increase the dose. For more detailed information, please see the leaflets that come with the medicine.
4. Notes when using bronchodilators
Strictly follow the doctor's prescription When a doctor prescribes medicine, you need to comply with the dose, time and course of taking the medicine. It is necessary to recognize abnormalities that occur during drug use and notify the doctor for appropriate and timely treatment.
Bronchodilators are not a cure for shortness of breath Many people mistakenly think that bronchodilators are a cure for shortness of breath, so whenever they find it difficult to breathe, they use bronchodilators. Such use sometimes makes the condition worse, because shortness of breath has many different causes, of which heart failure is a very common cause of shortness of breath. Using bronchodilators for heart failure can make the condition worse.
Aerosol - inhaled drugs are preferred over oral drugs Many people still mistakenly believe that new oral or injectable drugs bring strong bronchodilator effects, so they often believe in oral drugs rather than spray - inhaler drugs. . However, most bronchodilators are produced in the form of aerosol - inhalation, in this form, the bronchodilators reach the airway mucosa directly very quickly, providing a rapid and strong bronchodilator effect. , while the concentration of the drug absorbed into the blood is very small, so it rarely causes side effects. Meanwhile, oral drugs must go through the process of being absorbed into the blood, then to the lungs, bronchial smooth muscle, so they often do not create a strong bronchodilator effect, while the side effects are many (due to the high concentration of drugs in the blood). high).
Need to use medicine correctly The same bronchodilator inhaler - but different manufacturers use different drug delivery devices. You need to have a solid understanding of how to use each respective drug delivery device. Common drug delivery devices on the market today include metered dose inhalers, turbuhaler inhalers, accuhaler inhalers, handihaler inhalers, and inhalers.
These different tools have different uses. To properly use these drug dispensers, when you are prescribed medication you need to ask carefully how to use each drug. Just to be on the safe side, after purchasing the medicine, you should bring your doctor the direct dosing instructions. Furthermore, you should re-read the instruction leaflet included in the medicine box, then use the medicine again the next time. Proper use of drugs ensures the effectiveness of treatment and avoids drug waste.
Oral bronchodilators have many side effects Beta 2 adrenergic agonists often cause side effects such as tremors, tachycardia, palpitations, some patients have cramps. People taking oral beta-2 agonists in combination with oral corticosteroids may have hypokalemia.
Xanthine group drugs often cause some complications Xanthine group bronchodilators have undesirable effects such as tachycardia, irritation of the stomach lining. Care should be taken when using this group of drugs because the therapeutic and toxic doses are very close to each other. The maximum dose is 10mg/kg/day, it is necessary to reduce the dose in renal and hepatic impairment. Do not use xanthine drugs together with macrolide antibiotics (erythromycin, clarithromycin, azithromycin) because of the risk of torsades de pointes.
Some bronchodilators can still cause allergies Oral bronchodilators are more allergenic. Some inhaled drugs can also cause allergies, in which allergic manifestations should be noted that breathing difficulty increases when using spray-inhaled drugs to treat shortness of breath, then, it is necessary to stop immediately and switch to another drug. .
Be careful when using bronchodilators in the following cases: Hyperthyroidism, cardiovascular disease, hypertension, arrhythmia, diabetes...
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