Drugs Used In Respiratory System Question And Answers

Drugs Used In Respiratory System

 Bromhexine

• Bromhexine is a derivative of the alkaloid vaccine which is obtained from the adhatoda vasica.
• Bromhexine is a potent mucolytic and mucokinetic.
• Bromhexine is capable of inducing thin copious bronchial secretion.

Bromhexine Mechanism Of Action

Bromhexine Side Effects

• Rhinorrhea
• Lacrimation
• Gastric irritation
• Hypersensitivity.

Read And Learn More: Pharmacology Question And Answers

 Salbutamol

Salbutamol is a sympathomimetic bronchodilator.

Inhaled salbutamol produces bronchodilatation in 5 min and its action last for 2 to 4 hours.

Salbutamol Mechanism Of Action

Pharmacological Actions

• Salbutamol leads to bronchodilatation.
• Salbutamol causes relaxation of the pregnant uterus.
• Salbutamol  leads to the dilatation of blood vessels that supply skeletal muscles.
• Salbutamol promotes hepatic glycogenolysis and the uptake of potassium in cells.

Salbutamol Therapeutic Uses

• Bronchial asthma as it causes bronchodilatation.
• Salbutamol delays premature labor.
• Salbutamol is useful in hyperkalemia as it increases the uptake of potassium ions in cells.

Salbutamol Side Effects

• Cardiac side effects such as tachycardia and palpitation are less prominent.
• Muscle tremors
• Presence of restlessness, nervousness, throat irritation, and ankle edema.
• Hyperglycemia can occur in diabetics.

Salbutamol And Cromoglycate Sodium

 Bronchodilators

Bronchodilators are used in the treatment of bronchial asthma.

The following are the bronchodilators:

1. Sympathomimetics:

• Selective β2 adrenergic agonists: Salbutamol, Terbutaline, Bambuterol, Salmeterol, Formoterol, Ephedrine
• Non-selective: Adrenaline

2. Methylxanthines: Theophylline, aminophylline, cholinetheophyllinate, hydroxyethyl theophylline, Theophylline ethanolate of piperazine, doxophylline

3. Anticholinergics: Ipratropium bromide, tiotropium bromide.

Sympathomimetics

• Selective β2 adrenergic agonists act by stimulating β2 receptors in bronchial smooth muscles and mast cells and increasing cAMP formation which leads to
  bronchodilatation, inhibit the release of histamine SRS-A from mast cells and promote mucociliary clearance.
  Selective β2 adrenergic agonists are the first-line drugs for bronchial asthma. On inhalation, these drugs are very well tolerated.
• Non-selective sympathomimetics, i.e. adrenaline. Adrenaline produces prompt and powerful bronchodilatation by acting through β2 adrenergic receptors. Its
  use is declining these days due to its dangerous side effects.

Methylxanthines

• Theophylline and aminophylline cause inhibition of phosphodiesterase and prevent degradation of cAMP and cGMP. This causes an increase in the accumulation of intracellular cAMP which leads to bronchodilatation,
  inhibit the release of histamine SRS-A from mast cells and promote mucociliary clearance.
• Methylxanthines potentiate the effect of sympathomimetics i.e. increases bronchodilatation and cardiac stimulation.
• Methylxanthines have a narrow margin of safety i.e. they can lead to tachycardia, palpitation, hypotension, and sometimes sudden death due to cardiac arrhythmia.
• Theophylline is given by oral route while aminophylline is given by slow IV infusion.

Anticholinergics

• Anticholinergics selectively block the effects of acetylcholine in bronchial smooth muscle and lead to bronchodilatation but these drugs have no effect on mucociliary clearance.
• Anticholinergics have less effect on bronchial asthma as compared to sympathomimetic drugs.
• They are administered through an inhalational route.
• In acute severe asthma combination of ipratropium bromide along with β2 adrenergic agonists provide more prolonged bronchodilatation.

Selective β2 Agonist For Bronchial Asthma

Selective β2 agonist activates β2 adrenoceptors present on airway smooth muscle and enhances the release of cAMP by activating the adenyl cyclase enzyme.

The mast cells have β2 adrenergic receptors that also respond to them.

So these drugs relax the smooth muscle of the airway and inhibit the release of bronchoconstriction chemical mediators from the mast cells and increase mucociliary transport by increasing ciliary activity.

 Ephedrine In Asthma

Salbutamol is fastest acting bronchodilator with a peak effect in 10 minutes while ephedrine is slow in onset, has low efficacy, and has frequent side effects.

That’s why salbutamol is preferred over ephedrine in asthma.

 isoprenaline in the treatment of asthma

• Bronchial airways contain β2 receptors which are responsible for producing bronchodilation. Salbutamol is a selective β2 agonist which is usually administered by the inhalational route during an acute asthmatic attack. Therefore, it produces bronchodilation and improves airflow without having any prominent adverse effect on other systems.
  In comparison, isoprenaline is a non-selective β receptor agonist exerting its action on both β1 and β2 receptors, though, it can dilate the bronchus (due to β2 agonism), its additional action on the β1 receptors can lead to tachycardia and even fatal arrhythmias at high doses.
• Salbutamol can be given by inhalational route whereas isoprenaline is given by IV route. Therefore the risk of extrapulmonary adverse effects due to β2 agonism like tremors and hypoglycemia more with isoprenaline as compared to salbutamol.

 Montelukast

Montelukast is a leukotriene antagonist.

Montelukast Mechanism Of Action

Montelukast competitively antagonizes (blocks) CysLT1 receptor-mediated bronchoconstriction, increased vascular permeability, and recruitment of eosinophils.

Montelukast Indications

Prophylactic therapy in mild to moderate asthma. In asthmatic patients, bronchodilatation, reduced sputum eosinophil count, suppression of bronchial inflammation, and hyperreactivity are noted.
In aspirin-induced asthma.

Montelukast Side Effects

• Headache and rashes.
• Churg-Strauss syndrome.

Treatment Of Bronchial Asthma And  Inhalational Corticosteroids

Classification Of Drugs Used For Treatment Of Bronchial Asthma

1. Bronchodilators

• Sympathomimetics:
  • Selective β2 adrenergic agonists: Salbutamol, terbutaline, bambuterol, salmeterol, formoterol, ephedrine
  • Non-selective: Adrenaline
• Methylxanthines: Theophylline, aminophylline, choline theophylline, hydroxyethyl theophylline, theophylline ethanolate of piperazine, doxophylline
• Anticholinergics: Ipratropium bromide, tiotropium bromide

2. Leucotriene antagonists: Montelukast, Zafilukast

3. Mast cell stabilizer: Sodium cromoglycate, Ketotifen

4. Corticosteroids

• Systemic: Hydrocortisone, prednisolone, and other
• Inhalational: Beclomethasone dipropionate, budesonide, flticasone propionate, flnisolide, ciclesonide

5. Anti-IgE antibody: Omalizumab.

Inhalational Corticosteroids

• Inhalational corticosteroids are beclomethasone dipropionate, budesonide, fluticasone propionate, flnisolide, ciclesonide.
• Inhaled glucocorticoids, i.e. beclomethasone, budesonide, fluticasone, and ciclesonide are the prophylactic agents in bronchial asthma. Ciclesonide is added later on. Ciclesonide is a prodrug and gets activated by esterases in bronchial epithelium.
• Since airway inflammation is present in early mild disease and bronchial remodeling starts developing from the beginning, it is advocated that inhaled steroids are the first step for all asthma patients.
• Inhaled steroids suppress bronchial inflammation, increase peak expiratory flow rate and reduce the need to rescue β2 agonist inhalation, and prevent episodes of acute asthma.
• Adverse effects of inhalational steroids are hoarseness of voice, dysphonia, sore throat, and asymptomatic or symptomatic oropharyngeal candidiasis. These side effects are reduced by using a spacer and rinsing the mouth after each dose.
• Inhaled steroids along with long-acting β agonists have synergistic action and are used in bronchial asthma and COPD. They are also used in moderate and severe persistent asthma. Examples are Fluticasone + Salmeterol, Budesonide + Formoterol.

Classify Drugs Used In Treatment Of Bronchial Asthma

Classification Of Drugs Used For Treatment Of Bronchial Asthma

1. Bronchodilators

• Sympathomimetics:
  • Selective β2 adrenergic agonists: Salbutamol, Terbutaline, Bambuterol, Salmeterol, Formoterol, Ephedrine
  • Non-selective: Adrenaline
• Methylxanthines: Theophylline, aminophylline, choline theophylline, hydroxyethyl theophylline, theophylline ethanolate of piperazine, doxophylline
• Anticholinergics: Ipratropium bromide, tiotropium bromide

2. Leucotriene antagonists: Montelukast, zafilukast

3. Mast cell stabilizer: Sodium cromoglycate, ketotifen

4. Corticosteroids

• Systemic: Hydrocortisone, Prednisolone, and other
• Inhalational : Beclomethasone dipropionate, Budesonide, Fluticasone propionate, Flunisolide, Ciclesonide

5. Anti­IgE antibody: Omalizumab