Anti-asthma drugs

Content

Introduction

Anti-asthmatics are drugs used to control asthma. Their use does not cure the disease but helps to reduce or prevent the ailments (symptoms) it causes, allowing you to lead a normal and active life.

Anti-asthmatics can be divided into two categories:

  • emergency medications (or symptomatic) to be taken as needed to relieve symptoms caused by asthma
  • control medications (or background) to be used in the long term, for preventive purposes, to reduce the likelihood of new asthma attacks

Anti-asthmatics are available in various pharmaceutical forms but are mainly administered by inhalation, using aerosol cans, self-inhalers, powder dispensers or nebulizers. The inhalation route, in fact, allows to reach the bronchi directly and to use lower doses of the drug than those necessary for other routes of administration, minimizing unwanted (collateral) effects in the rest of the body. In particular cases, related to the form and severity of asthma, anti-asthmatics can be taken by mouth or injected subcutaneously or intravenously.

The goals of drug therapy are:

  • achieve satisfactory symptom control
  • allow the carrying out of any activity, including sporting practices
  • reduce the need to resort to emergency drugs
  • prevent, or at least contain, the risk of future asthma attacks (exacerbations)
  • maintain lung function and reduce the risk of worsening
  • limit the side effects of drugs as much as possible, using the minimum effective doses

Types of asthmatics

Anti-asthma drugs are divided into two main classes and are often used in combination with each other, either by using them one after the other or in combined preparations:

  • bronchodilators, relax and dilate the airways
  • anti-inflammatory, combat the state of inflammation and sensitivity of the airways

The choice of drugs, their dosage and duration of treatment are evaluated case by case, based on the severity of the asthma and the characteristics of the person, such as age and general health conditions. Once the appropriate therapy has been identified, the asthmatic person is subjected to constant monitoring to assess the response to the treatment undertaken and to adapt the treatment plan to the progress of the disease, with an increase or decrease in drugs depending on the case.

Bronchodilators

This class of drugs counteracts the closure of the bronchi (bronchoconstriction) and associated respiratory disorders by inducing relaxation of the contracted muscles surrounding the bronchial wall. The administration of bronchodilators determines the increase in the diameter of the airways, allowing the regular passage of air and the return to normal breathing.

Bronchodilators comprise three classes of drugs:

  • beta2-agonists (beta-adrenergics)
  • anticholinergics (muscarinic receptor antagonists)
  • theophylline (methylxanthines)

Beta-2 agonists

Beta2-agonists are potent bronchodilators, usually taken by inhalation, which are divided into multiple groups based on the duration of their effects.

THE short-acting beta2-agonists (Short-Acting Beta2-Agonists or SABA), such as the salbutamol and the terbutaline, act within minutes of their administration, allowing respiratory crises to be resolved quickly and effectively. Their effects wear off within 3-6 hours, depending on the active ingredient used, so they are indicated as emergency drugs to be used during asthma episodes to obtain immediate relief from ailments (symptoms). SABAs are also effective in the short-term prevention of exercise-induced asthma (exercise-induced asthma) when inhaled 20-30 minutes before physical activity begins. Recent studies have shown that on-demand treatment with SABA alone increases the risk of future asthma crises, even severe ones, and mortality from asthma, because bronchodilators do not intervene on the inflammation responsible for symptoms. The new international guidelines on asthma from the Global Initiative for Asthma (GINA) therefore recommend , the use of SABA in association with inhaled corticosteroids which, on the other hand, have an anti-inflammatory action. The use of SABAs should not exceed 2-3 times a week. A higher frequency of use indicates poor asthma control and requires a re-evaluation of the treatment plan with your doctor.

THE long-acting beta2-agonists (Long-Acting Beta2-Agonists or LABA), such as the formoterol and the salmeterol, and i beta2-agonists with an ultra-long duration of action (Ultra-Long Acting Beta2-Agonists or Ultra-LABA), such as the "indacaterolor and the vilanterol, allow to prolong bronchodilation, respectively, for 12 and 24 hours. The long duration of action that distinguishes them makes them able to control day and night asthma symptoms, prevent exercise asthma in the long term and reduce the use of emergency drugs, improving the person's quality of life.LABAs and Ultra-LABAs should be used regularly, in one or two daily doses, always in combination with inhaled corticosteroids (in a single inhaler or in separate inhalers). Their use alone (monotherapy), in fact, increases the probability of severe asthma attacks, even fatal, as the asthmatic person, in the absence of respiratory symptoms, may not be aware of any worsening of the disease.

Anticholinergics (muscarinic receptor antagonists)

Anticholinergics, such as "ipratropium bromide (short-acting) and the tiotropium bromide (long-acting), inhibit the contraction of bronchial smooth muscle and the excessive production of mucus in the bronchi. These drugs, administered by inhalation, have effective bronchodilator effects but lower than those of beta2-agonists, to which they are generally combined to obtain a increased airway dilation. Ipratropium is used in combination with short-acting beta2-agonists in the emergency treatment of acute seizures, while tiotropium is used as an add-on drug in background (long-term) therapy based on inhaled corticosteroids and long-acting beta2-agonists. Anticholinergics are also used as an alternative to beta2-agonists in cases where the latter cause intolerable undesirable effects.

Theophylline (methylxanthines)

There theophylline is a bronchodilator with anti-inflammatory properties, naturally occurring in tea leaves, coffee and cocoa seeds. In the past, theophylline was widely used in the treatment of asthma but its role has progressively diminished with the discovery of new drugs, more effective and burdened with fewer side effects.Today, theophylline is mainly prescribed as an adjunct drug to inhaled corticosteroids in the background therapy of difficult to control asthma cases. Its use requires careful monitoring of the drug levels in the blood (therapeutic monitoring) as too low doses of theophylline are ineffective, while too high doses are toxic and can lead to seizures and cardiac arrhythmias, sometimes fatal. Not being effective by inhalation, theophylline is administered by mouth or rectally in the form of suppositories. The most widely used formulation is slow-release tablets which prolong the bronchodilator effects up to 24 hours and keep the concentration in the blood constant, reducing the risk of side effects. In a hospital setting, theophylline is administered intravenously as an emergency drug in severe asthma attacks that do not respond to treatment with other antiasthmatics. In these cases it is used in the form of aminophylline (water soluble) in slow infusion.

Anti-inflammatories

The anti-inflammatories commonly used in the treatment of asthma belong to three classes of drugs:

  • corticosteroids (glucorticoids)
  • antileukotriene (leukotriene modulators)
  • chromones (mast cell stabilizers)

Corticosteroids

Corticosteroids, better known as cortisones or steroids, are the most potent anti-inflammatories available.

They can be administered by inhalation, oral or injected, depending on the severity of the asthma, always using the minimum effective dose capable of ensuring satisfactory control of (disturbances) symptoms and reducing the risk of undesirable (side) effects as much as possible. .

THE inhaled corticosteroids they are considered the first choice drugs in the long-term treatment of all forms of asthma, both in adults and children.They are prescribed in the presence of frequent asthma attacks and in case it is necessary to resort to beta2-agonists with short duration of action more than 2 times a week. Used daily and for a long time, inhaled corticosteroids reduce swelling (edema) airways, mucus production and bronchial irritability. Furthermore, they improve respiratory function and decrease the risk of further asthma attacks, eliminating, or at least reducing, the need to use emergency drugs. The dosage and duration of therapy depend on the frequency and intensity of the symptoms, as well as the active ingredient used. The most used corticosteroids are: fluticasone, flunisonide, beclomethasone, ciclesonide, triamcinolone, budesonide And mometasone. Generally they are administered once or twice a day, alone or in combination with other drugs, and can be used safely even for several years, as long as dosed and inhaled correctly. It is very important that the therapy is followed every day and for the entire period indicated by the doctor even if there are no symptoms. Failure to comply with treatment (adherence to therapy), in fact, decreases asthma control and increases the risk of exacerbations.

THE oral corticosteroids, to be taken by mouth in the form of tablets or syrups, are reserved for cases in which it is necessary to ensure greater quantities of the active ingredient circulating in the body. Drugs such as methylprednisolone, the prednisolone and the prednisone, are used in severe asthma attacks and in asthmatic people who do not respond to treatment with the best inhalation regimen (based on multiple drugs used at high doses).Normally oral corticosteroids are prescribed for short courses of therapy, due to even serious side effects related to long-term oral administration, but in cases of severe asthma they can be prescribed for an indefinite period of time. It is up to the physician to determine whether the benefits deriving from the use of oral corticosteroids outweigh the risks associated with the potential occurrence of side effects. In case of prolonged treatments, cyclical intake or administration of high doses, corticosteroids must be discontinued gradually, through a progressive reduction doses, to allow the adrenal glands to resume the physiological production of cortisol which is blocked by therapy.In the hospital, in the presence of severe and uncontrolled seizures, corticosteroids are commonly administered intravenously.

Antileukotrienes (leukotriene modulators)

Antileukotrienics, such as montelukast, lo zafirlukast and it zileuton, prevent the action or formation of leukotrienes, substances produced by the body during inflammatory and allergic reactions and which cause the airways to narrow and swell. Since their anti-inflammatory action is weaker than that exerted by corticosteroids, leukotrienics are considered additional drugs in the continued treatment of mild or moderate asthma, where inhaled corticosteroid therapy does not ensure adequate control of the disorders. Antileukotrienics are indicated in the prevention of exertional asthma but not in the treatment of acute seizures, and appear to offer "effective protection from" aspirin-induced asthma and seasonal allergic rhinitis.Being administered by mouth, leukotrienics represent a "useful alternative" to the use of oral corticosteroids in people who are unable to perform proper inhalation technique, such as children, for whom a preparation in the form of chewable tablets is also available and granulate (montelukast).

Chromones (mast cell stabilizers)

The chromones, such as the sodium cromoglycate and the sodium nedocromil, prevent the release of inflammatory substances into the airways by mast cells, cells involved in allergic and inflammatory reactions. These drugs, administered by inhalation in cases of mild or moderate asthma, are indicated in the prevention of asthmatic attacks induced by effort and exposure to cold air or allergens, substances capable of triggering an inflammatory and allergic reaction. inhaled corticosteroids and antileukotrienes, chromones must be used regularly every day and cannot be used as emergency drugs, as they do not allow for ongoing seizures to be resolved. Their prolonged use reduces the sensitivity of the bronchi, the severity of symptoms and the need for bronchodilators. Not all asthmatic people benefit from the use of chromones but children generally respond very well to treatment.

Biological drugs

Thanks to genetic engineering it has been possible to develop several biological drugs used as additional maintenance therapy in the treatment of asthma that does not respond to treatment with the control drugs examined so far. These are monoclonal antibodies, similar to the antibodies produced in the body, which act in a targeted manner against the molecules responsible for inflammation in various forms of asthma. Each of these drugs is designed to recognize a specific molecular target and neutralize its effects by binding to it.

L'omalizumab it binds to immunoglobulin E (Ig-E) circulating in the blood, preventing its binding with inflammatory cells (mast cells and basophils) and consequently inhibiting allergic reactions in case of exposure to an allergen.

The mepolizumab, the benralizumab and the reslizumab (reserved for hospital use) block the action of interleukin 5 (IL-5), responsible for the activation and proliferation of eosinophils, a type of white blood cell that supports inflammation and reactivity of the airways.

The dupilumabinstead, it is directed against the alpha receptor of interleukin 4 (IL-4) also shared by IL-13 thus blocking the binding of both cytokines IL-4 and IL-13 which play a fundamental role in the development of allergic asthma.

Monoclonal antibodies are administered by injection, subcutaneously or intravenously (reslizumab), usually every 2-4 weeks. Their use is reserved for people with severe and persistent asthma, resistant to other drugs, which have certain characteristics detected by specific tests.

L'omalizumab, in particular, it is prescribed to people with allergic asthma, sensitive to allergens present in the air all year round (perennial aeroallergens), such as pet hair, dust mites or environmental mold spores.

In addition to significantly improving asthma control and respiratory function, biological drugs reduce the frequency and severity of asthma attacks, decrease the doses of inhaled corticosteroids and, in some cases, eliminate the use of oral corticosteroids .

Several studies are currently underway on new monoclonal antibodies directed against other molecular targets implicated in the mechanisms that trigger asthma disorders.

Undesirable (side) effects

Anti-asthmatics, like all drugs, can induce side effects, although not all people experience them. Some are mild and transient ailments, destined to disappear as the organism adapts to the drug, others, on the other hand, can be serious or intolerable and require the interruption of treatment.

Below are the main side effects of the different classes of anti-asthma drugs.

More detailed information is available on the package leaflets accompanying each pack of medicine.

Bronchodilators

  • beta2-agonists (by inhalation), they rarely cause serious side effects when used at recommended doses. The main disorders (symptoms) associated with their use are:
    • tremor (especially in the hands)
    • muscle cramps
    • headache
    • increased heart rate (tachycardia)
    Usually these symptoms last a few minutes, or at most a few hours, and tend to spontaneously decrease with the continuation of therapy
  • anticholinergics (by inhalation), they are safe and generally well tolerated drugs. Their most common side effects are:
    • dry mouth
    • hoarseness
    • cough
    • headache
    Accidental dispensing of drugs into the eyes during inhalation may cause eye or vision disorders which should be reported to your doctor immediately
  • theophylline (by mouth). The most frequent side effects of theophylline are:
    • nausea
    • He retched
    • stomach ache
    • headache
    • sleep disturbances (insomnia)
    • restlessness
    • perception of heartbeat (palpitations)
    • increased heart rate (tachycardia)
    • increased urine output
    Generally these symptoms are caused by too high doses and can be avoided by measuring the amount of drug in the blood (therapeutic monitoring) to proceed with a reduction of the dosage based on the results of the tests.If severe changes in the rhythm of the heart (arrhythmias) or seizures occur, it is necessary to undergo an immediate medical evaluation. These symptoms could represent the first signs of intoxication that can lead to cardiac arrest or cause permanent brain damage if not action is taken quickly.

Anti-inflammatories

  • corticosteroids (by inhalation), the use of inhaled corticosteroids can induce the following side effects:
    • fungal infection in the mouth and throat (oral thrush or thrush)
    • hoarseness
    • sore throat
    These are frequent but not serious disorders that can normally be reduced or avoided by adopting simple measures at the time of administration to eliminate drug residues in the oral cavity. Just use a spacer for the spray cans and / or rinse your mouth or brush your teeth immediately after inhalation. When inhaled correctly and at the indicated doses, inhaled corticosteroids rarely cause side effects that affect the whole body (systemic effects )
  • corticosteroids (by mouth), the use of corticosteroids in tablets and syrups is associated with the risk of various side effects, since the drugs, instead of acting locally, as occurs when they are inhaled, enter the circulation through the blood and are distributed throughout the body. The administration of oral corticosteroids in high doses and for prolonged periods can cause side effects, even serious, such as:
    • decreased bone mineral density (osteoporosis)
    • increased appetite and consequent weight gain
    • mood swings
    • water retention
    • increased blood pressure (hypertension)
    • thinning of the skin and bruising (especially in children and older people)
    • increased blood sugar (mainly in people with diabetes or impaired glucose tolerance)
    • increased susceptibility to infections (usually in elderly or immunocompromised people)
    • cataracts (in adults)
    • glaucoma (in people with a family history of glaucoma)
    In children and adolescents, the prolonged use of oral corticosteroids at medium-high doses can cause a slowdown in growth which, however, in most cases does not affect the achievement of the expected height in adulthood
  • leukotriene (by mouth), the most common symptoms that can occur with the use of antileukotrienics include:
    • abdominal pain
    • headache
    • upper respiratory tract infections (usually minor)
    • nausea
    • He retched
    • diarrhea
  • chromones (for inhalation), chromones generally cause negligible symptoms, such as:
    • dry mouth
    • throat irritation
    • change in taste or unpleasant taste in the mouth
    • cough

    Biological drugs (for injection)

    The most frequent side effects of monoclonal antibodies are:
    • headache
    • sore throat
    • fever
    • allergic reactions to the drug (rash, itching, hives, tachycardia)
    • joint and muscle pains
    • nausea, diarrhea
    • reactions at the injection site (pain, redness, itching, swelling and burning)
    Generally, reactions where the injection was given occur at the start of treatment and resolve spontaneously within a few days.

Bibliography

Asthma UK. Add-on asthma treatments (English)

Asthma UK. Biologic therapies for severe asthma (English)

Asthma UK. Theophylline (English)

NHS. Asthma. Treatment (English)

In-depth link

Global Initiative for Asthma. Global strategy for the management and prevention of asthma. (Update 2019)

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