Drugs acting on Respiratory system Flashcards
Classification of drugs that act on the respiratory system?
●antitussive drugs;
●expectorants;
●drugs for the treatment of bronchial obstruction syndrome
(bronchial asthma,
chronic obstructive pulmonary disease)
●drugs for the treatment of pulmonary edema.
Antitussive Drugs & classification?
》Antitussive drugs are drugs that suppress the cough.
》They are used to eliminate nonproductive or exhausting cough, that can interfere with sleep.
■Antitussive drugs are divided into two groups.
》The classification is based on the mechanism of their action.
Classification:
》 centrally acting drug
(opioids - codeine,
nonopioids - dextromethorphan)
》peripherally acting drugs
(prenoxdiazin).
Centrally acting drugs?
●Centrally acting drugs depress the cough center in the medulla oblongata.
●Codeine stimulates opioid receptors and suppresses the cough.
●It can cause drug dependence and all other adverse effects of opioids.
Dextromethorphan resembles opioids on a chemical structure but does not cause analgesia and abuse.
The mechanism of the antitussive action is unknown.
Dextromethorphan
blocks the NMDA, a3ß4 nicotinic receptors,
stimulates
8₁ and 82 receptors,
inhibits the reuptake of serotonin.
Peripherally acting drugs?
●Cause anesthesia of the respiratory tract mucosa and, as a result,
suppress the cough reflex.
●Prenoxdiazin is used for cough of a bronchial origin.
It should not be chewed because it can cause numbness of the mouth and tongue.
●The efficacy of prenoxdiazin is lower
than that of centrally acting drugs.
Expectorants & classificaton?
●Expectorants are the drugs that stimulate the bronchial secretion and
reduce its viscosity.
●They are divided into two groups.
The classification is based on the mechanism of their action.
》》Classification,
• reflex acting drugs - irritants (Thermopsis, guaifenesin);
• directly acting drugs
(sodium bicarbonate, potassium iodide, ambroxol, acetylcystein).
Irritants?
●Exert a local irritating action on the gastric mucosa receptors that stimulate bronchial secretion by reflex via nervus vagus and make sputum more liquid.
●Their main adverse is vomiting. Guaifenesin is the most often used irritant because it is highly effective and safe.
Directly acting drugs?
●(sodium bicarbonate, potassium iodide)
are absorbed into the systemic circulation and transported into the bronchi
●They increase the volume of the sputum and make it less viscid.
●Iodides are rarely used because they can affect the thyroid gland and cause allergies.
●Mucolytics disrupt disulfide bonds in the sputum and make it more liquid.
●Ambroxol is the best drug in pediatric practice.
Acetylcystein is used for very thick sputum.
》It is also used as an antidote to acetaminophen.
Drugs for the Treatment of Bronchial Obstruction Syndrome
(Bronchial Asthma, Chronic Obstructive
Pulmonary Disease)
》According to GINA
(Global Initiative for Asthma),
bronchial asthma is a heterogeneous disease, which is characterized by chronic airway inflammation.
●The main symptoms are
》wheeze,
》shortness of breath,
》chest tightness,
》cough or
》variable expiratory airflow limitation.
●These symptoms are triggered by
》allergens,
》irritants,
》physical exercises,
》changes in weather,
and even viral respiratory infections.
All types of triggers activate mast cells
and cause the release of inflammatory mediators or stimulate their synthesis.
●The inflammatory mediators activate a cascade of a cellular response that leads to bronchoconstriction and bronchial inflammation.
●The chronic inflammatory process causes bronchial hyperactivity.
●This means that bronchi become more sensitive to histamine and other mediators.
Drugs for treating bronchial asthma?
》The main problems of bronchial asthma are bronchoconstriction and inflammation.
》All drugs used for the treatment of bronchial asthma are divided into two groups.
●Bronchodilators
》adrenergic agonists
》muscarinic antagonists
》methylxanthines
●anti-inflammatory drugs
》corticosteroids
》leukotriene pathway inhibitors
》mast cell stabilizers
》anti-IgE
Effects of tobacco?
●Tobacco smoking usually leads to chronic obstructive pulmonary disease
(COPD).
●It looks like a combination of chronic bronchitis and emphysema symptoms.
●The mainstay of COPD treatment is smoking cessation.
●The drugs of choice are muscarinic antagonists.
●Exacerbation of bronchitis is treated with antibiotics.
Bronchodilator types?
●Adrenergic agonists
●Muscarinic antagonists
●Methylxanthines
Adrenergic agonists & types?
●They stimulate ß₂-adrenergic receptors in the smooth muscles of bronchi,
relax them, and
cause bronchodilation.
●Classification:
》 non-selective
epinephrine - a, ß;
ephedrine - a, ß;
isoprenaline - B1,2,3;
》 selective (B₂)
- short-acting drugs:
salbutamol
fenoterol;
- long-acting drugs:
salmeterol,
formoterol.
Non-selective adrenergic agonists?
● (epinephrine - a, ß; ephedrine - a, ß;
isoprenaline - B1,2,3)
are rarely used because they cause cardiovascular adverse effects.
●They stimulate a₁-adrenoceptors leading to vasoconstriction,
and B₁-adrenoceptors - tachycardia, tachyarrhythmia.
Selective adrenergic agonists?
●Stimulate ß₂-adrenergic receptors but
in high doses can act on ß₁.
The route of their administration is inhalation.
Short-acting drug
(salbutamol, fenoterol)
act quickly and for a short time.
And they are used to relieve and terminate asthma attacks.
The therapeutic effect of long-acting drugs
(salmeterol, formoterol) develops
slowly but lasts for a long time.
They are used in combination with glucocorticoids for prophylaxis.
Short-acting B₂-adrenergic agonists are the best drugs to relieve asthma attacks.
Muscarinic antagonists?
●They inhibit the influence of the parasympathetic nervous system (nervus vagus) due to the block of the M-cholinergic receptors in the smooth muscles of the bronchi, leading to the relaxation of them and bronchodilation.
●Ipratropium acts selectively on the M3 receptors and is a bronchodilator of choice in COPD treatment.
