The list of expectorant drugs that can be used for asthma bronchitis is quite extensive, but there are only a few truly effective ones: 1) acetylcysteine (commercial names – acetylcysteine, ACC, mucomist , etc.); 2) mesna , or mercaptoethanesulfonate ( mistabron ); 3) Bromhexine ( Bizolvon , Bromhexine, Solvin , etc.); 4) ambroxol (ambroxol, ambrosan , lazolvan , etc.); 5) carboxymethylcysteine ( carbocysteine , mucodin , mucopront , etc.); 6) iodine preparations (potassium iodide and mixtures based on it); 7) alkaline mixtures based on sodium bicarbonate (soda).
The mechanisms of action of modern expectorants are mainly associated with an improvement in the rheological properties of sputum – a decrease in viscosity, elasticity and adhesion, as well as a decrease in the amount of mucus formed. Drugs that normalize rheological characteristics are represented by: 1) mucolytics (substances that thin mucus), 2) secretion rehydrators (increasing the water content in it), and 3) agents that reduce adhesion (sticking) of sputum to the bronchial wall.
Mucolytics act directly on bronchial mucus: if a small amount of medication is added to a portion of viscous sputum, it will turn into a cloudy and completely non-viscous liquid in a few minutes. The group of mucolytics includes two classes of chemical compounds: proteolytic enzymes and thiols. Trypsin, chymotrypsin and analogs containing them are among the first. The mucolytic effect of enzymes is associated with the cleavage of peptide (protein) bonds of mucus glycoprotein molecules. In the 50s-70s. they were used quite widely, but it soon became clear that proteolytic enzymes contribute to the development of emphysema and pneumosclerosis. Therefore, they cannot be prescribed for chronic lung diseases, the progression of which can lead to emphysema and pneumosclerosis. Asthma is one of these diseases. In addition, there are other mucolytics – thiols – no less effective and absolutely safe.
Unlike proteolytic enzymes, thiols (acetylcysteine and mesna ) thin sputum by breaking the disulfide “bridges” that bind glycoprotein molecules. The mechanism of this reaction is quite simple, but the effectiveness of such an impact is unusually high: sputum liquefies almost instantly. Therefore, thiols are also used in otorhinolaryngology to clear viscous mucus from the upper respiratory tract. By the way, other thiol derivatives (for example, the domestic drug unitiol ) can also be effectively used as mucolytic agents. Most thiols are used in the form of tablets or syrups, injections and inhalations. When thiols are used orally, they are absorbed from the digestive tract into the blood, secreted through the wall of the bronchus, thinning and exfoliating, first of all, the parietal layer of mucus. And this significantly increases the effectiveness of the expectorant action. That is, when thiols are taken orally (as well as when injected), they act EXTRABRONCHIALLY, getting into the lumen of the bronchus through its wall from the blood. When inhaled, thiols act ENDOBRONCHIALLY, as they enter directly into the lumen of the respiratory tract. Therefore, if there is a lot of mucus in the lungs, the drug does not affect the parietal layer of the secret, which does not allow for the most effective expectorant effect. In such cases, it is better to combine the use of thiols inside with inhalations.
The scientific literature describes many cases where the use of thiols, in particular acetylcysteine, causes bronchospasm with suffocation. However, prior inhalation of a bronchodilator prevents it. Contraindications for the use of thiols inside are severe chronic diseases of the digestive system: thinning of the mucus eliminates its protective effect, which can lead, for example, to an exacerbation of peptic ulcer and other ailments. In such cases, these agents are recommended to be used in smaller doses and mainly in the form of inhalations.
The extrabronchial mechanism of action is also inherent in another class of substances – iodine salts, which are used in the form of mixtures and very rarely in the form of solutions for intravenous administration. Being absorbed into the blood, they are then secreted through the wall of the bronchus into its lumen and, by virtue of the laws of osmosis, increase the water content in the mucus ( rehydrate it), facilitating coughing. An unpleasant property of these drugs is irritation of the skin and mucous membranes, since it is through them that iodine salts are secreted. This is sometimes manifested by a rash and itching, exacerbation of chronic inflammation of the mucous membranes in various organs, which naturally limits their use. A positive property of drugs containing iodine salts is a fairly pronounced antifungal effect. Therefore, one of the additional indications for the appointment of iodine mixtures is the development of candidiasis during treatment with inhaled steroids.
Alkaline solutions, in particular sodium bicarbonate (sodium bicarbonate), which are used mainly in the form of inhalations, also have a mucus rehydrating effect. Recommendations such as “plentiful alkaline drinking”, declared as expectorant therapy, are rather doubtful. To the above, we can add that, depending on the concentration, soda solutions also cause alkaline hydrolysis of mucus, which increases the efficiency of expectoration. Thus, the expectorant action of saline solutions is based on the rehydration of bronchial mucus, that is, an increase in water in it. This reduces its adhesion (sticking) to the wall of the bronchus, and according to some reports, it also reduces the viscosity.
Another class of pharmacological substances that reduce the adhesion of sputum is represented by bromhexine and its derivative, ambroxol. Bromhexine is a substance of natural origin: for the first time it was isolated from a plant. Subsequently, its chemical synthesis was carried out, and it became widely used in pulmonology. To date, Bromhexine and Ambroxol are the most effective and safe expectorants. They are usually used in the form of tablets and mixtures. The main mechanism of action of bromhexine and its analogues is the stimulation of the production of special substances in the lungs – surfactants , which have a high surface activity (similar to synthetic detergents). Therefore, rising up from the alveoli (where they are produced), surfactants “wash” the mucus from the bronchial wall. Preparations of the bromhexine group not only have an effective expectorant effect, but also, when taken for a long time (over 3 months), contribute to the normalization of secretion, reducing the amount of mucus formed in the respiratory tract. Long-term treatment with bromhexine at a dose of 48 to 96 mg per day for 3-6 months, especially in the autumn-spring periods, improves not only bronchial drainage, but also gradually normalizes secretion, sometimes to almost complete absence of sputum. In the indicated doses, these drugs are absolutely harmless. And according to the data available in the literature, patients who regularly take lazolvan or bromhexine suffer exacerbations of the disease twice as rarely.
The most complete cleansing of the respiratory tract in asthma and bronchitis from excess mucus (which worsens bronchial patency and reduces the effectiveness of inhaled anti-inflammatory and antiallergic drugs) can also be achieved by reducing its amount in the lungs. For this purpose, drugs are used that affect its production by mucus-forming cells and glands. These drugs include S- carboxymethylcysteine ( carboxycysteine , or carbocysteine ), produced under various commercial names. It is usually given in capsules or as a syrup. An unpleasant side effect of carboxycysteine is its ability to exacerbate chronic diseases of the digestive tract. Therefore, it cannot be used for a long time.
And in conclusion, I would like to warn doctors against a very common mistake: TRY NOT TO PRESCRIBE PATIENTS WITH ASTHMA DRUGS THAT SUPPRESS THE COUGH (AS SO MUCH HAPPENS), ESPECIALLY THE CODEINE SERIES. Such an action will only disrupt bronchial drainage, aggravate bronchial obstruction and ultimately worsen the patient’s condition. The same applies to drugs of the non- codeine series, for example, libexin , synecode , etc.
As already mentioned, almost all severe cases of asthma uncontrolled by bronchodilator aerosols are associated with widespread airway obstruction with mucous plugs . IN THIS CONNECTION, I REPEAT AGAIN: IF THE BRONCHOR DILATIVE AEROSOLS POORLY REMOVE A SHOCKING ATTACK, AND THE MUCISE IN THE FORM OF FIBER OR STRANDS IS EXHAUSTED FROM THE LUNGS WITH GREAT DIFFICULT, THERE IS A POSSIBLE OBTURATION (BLOCKAGE) OF THE BRONCH. forget about expectorants.