DRUGS AGAINST COUGH
DRUGS AGAINST COUGH
Introduction to cough:
- Productive (with expectoration)
- Non-productive (dry cough).
- Dry cough – Suppressed by anti-tussive agent.
- Productive cough – Suppressed by expectorants.
- MOA: By increasing bronchial secretions/by reducing its viscosity.
- Drugs: Potassium iodide, Bromhexine & Ambroxol.
1. Potassium iodide:
- Direct action – By irritating bronchial glands.
- Indirect action – By gastric irritation increasing bronchial secretions.
- Interferes with thyroid function tests.
- On prolonged use – Cause hypothyroidism.
- Cause acne flare-up in adolescents.
- In pregnancy – Risk of fetal hypothyroidism.
- In iodine- sensitive patients.
- Causes mucopolysaccharides depolymerization —> Resulting mucolysis (less viscid mucus).
- Metabolite of bromhexine.
- Also a mucolytic drug.
II) ANTITUSSIVE DRUGS:
- Should be used only for dry (non-productive) cough.
- Suppresses cough by,
- Direct action on CNS.
- Indirect action by inhibiting cough impulses in respiratory tract.
- Codeine, pholcodine, noscapine & dextromethorphan.
- Dry cough is suppressed by anti-tussive agent.
- Productive cough is suppressed by expectorants.
- Expectorants increase bronchial secretions/by reducing its viscosity.
- Potassium iodide, Bromhexine & Ambroxol are all expectorants.
- Potassium iodide acts by irritating bronchial glands & Indirect action – By gastric irritation increasing bronchial secretions.
- Potassium iodide interferes with thyroid function tests & their on prolonged use cause hypothyroidism.
- KI cause acne flare-up in adolescents.
- KI is contraindicated in pregnancy due to risk of fetal hypothyroidism & in iodine- sensitive patients.
- Bromhexine causes mucopolysaccharides depolymerization —> Resulting mucolysis (less viscid mucus).
- Ambroxol, metabolite of bromhexine is a mucolytic drug.
- Antitussive drugs are used only for dry (non-productive) cough.
- Codeine, pholcodine, noscapine & dextromethorphan are all antitussives.