Drugs on respiratory system

Question 1

respiratory stimulants

Answer 1

• doxapram (IV)
• A CNS stimulant that act on both the carotid chemoreceptors and respiratory centre in brain stem
• urge to breathe in ventilatory failure (increase in PO2, decrease inn PCO2)

Question 2

respiratory depressants

Answer 2

• ethanol: diffuse into cell membrane of the nerve cells to inhibit passive neuronal flux of Na
• narcotic drugs: codeine and morphine
• H1-histamine receptor antagonist (1st gen): promethazine

Question 3

Drugs inducing asthma

Answer 3

• aspirin and NSAID: blocking cyclooxygenase and thus produces more leukotrienes via lipoxygenase causing bronchoconstriction
• beta blockers: propranolol

Question 4

Antitussives

Answer 4

peripheral: syrups and lozenges above the larynx, water aerosol inhalation and warm environment below larynx -> reduce the sensitivity of cough receptor to irritants
Central: codeine and noscapine (opioid), dextromethorphan (nonopioid) -> suppress the cough centre in medulla and reduce sensitivity to peripheral stimulus

Question 5

Expectorant

Answer 5

• stimulate the hypersecretion of mucin from the mucin secreting cells -> increase in amount but decrease in viscoscity
• help remove excessive secretions by innducing cough centre activity by the increased volume
• e.g. KI, guaifenesin

Question 6

Mucolytics

Answer 6

• N-acetylcysteine/carbocisteine: break the disulphide bonds between the glycoproteins to thin them
• Bronchitis: polysaccharide fibres
• bromhexine: disrupt the structure of acid mucopolysaccharide

Question 7

recombinant human deoxyribonuclease I (dornase alfa)

Answer 7

managementn of cystic fibrosis
cleave the DNA left by dead neutrophils extracellular in the mucin which makes it thick
reduce length, and therefore thins the mucus

Question 8

Surfactant

Answer 8

natural surfactant: curosurf
synthetic surfactant: colfosceril
Used in management of IRDS, via endotracheal tube directly into the bronchial trees

Question 9

Allergic rhinitis- symptoms

Answer 9

• runny nose. nasal congestion, sneezing, itchiness and redness

Question 10

Allergic rhinitis- treatment

Answer 10

• H1-antihistamine: first gen- chlorphenamine, diphenhydramine (sedative, cross BBB)
  second gen- loratadine, cetirizine (non-sedative, do not cross BBB)
• decongestant: alpha 1 agonist (inhalation or oral) phenylephrine
  sympathomimetic drugs- pseudoephedrine

Question 11

Allergic rhinitis- combination therapy

Answer 11

• loratadine/ cetirizine + pseudoephedrine
• glucocorticoid: beclomethazone (intranasal)
• anti-allergic mast cell stabiliser (prophylaxis): cromolyn sodium (intranasal)