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1. DRUGS FOR COUGH By:- DR. AJAY HALWAI ASSOCIATE PROFESSOR, DEPTT. OF PHARMACOLOGY This Photo by Unknown author is licensed under CC BY-NC-ND . This Photo by Unknown author is licensed under CC BY-ND .

2. COUGH A protective reflex for expulsion of respiratory secretions and foreign particles from air passages. Due to stimulation of mechano- or chemoreceptors in throat and respiratory passages or stretch receptors in the lungs. Productive cough( usefull ) -serves to drain the airway  nonproductive cough (useless)- should be suppressed. The commonest cause of acute cough (lasting < 3 weeks) is respiratory viral infections.

3. DEMULCENTS AND EXPECTORANTS DEMULCENTS - It soothes the throat; provide symptomatic relief in dry cough,  Reduces afferent impulses from irritated pharyngeal mucosa. EXPECTORANTS - Increases bronchial secretion or reduce its viscosity, facilitating its removal by coughing. Sod. & potassium citrate- increase secreation by salt action Guaiphenesin, vasaka , tolu balsam enhance bronchial secretion and mucociliary function. Guaiphenesin- US-FDA approved However, evidence of efficacy of expectorants is non-conclusive, Steam inhalation and proper hydration may be more helpful

4. Mucolytics Bromhexine : derivative of the alkaloid vasicine obtained from Adhatoda vasica (Vasaka) Depolymerises mucopolysaccharides & breaks sputum fibres by lysosomal enzymes.  Side effects: rhinorrhoea, lacrimation, nausea, gastric irritation, hypersensitivity. Dose: adults 8 mg TDS, children 1–5 years 4 mg BD, 5–10 years 4 mg TDS. Ambroxol : metabolite of Bromhexine Similar action, uses and side effects as Bromhexine Dose: 15–30 mg TDS.

5. Mucolytics (Contd.) Acetylcysteine : opens disulfide bonds in mucoproteins; liquefies viscid sputum Orally (200–600 mg TDS) & by inhalation (10–20% nebulized solution) 10–20% acetylcysteine sol. directly into the respiratory tract of Intubated patients to remove mucus plugs. Injectable solution nebulized/ instilled through tracheostomy tube Uses: in tracheostomy, asthmatic bronchitis, cystic fibrosis patients. Side effects: gastric discomfort & rashes Carbocisteine : similar as Acetylcysteine Dose: orally (250–750 mg TDS) Contraindicated in peptic ulcer patients

6. ANTITUSSIVES Raise threshold of cough centre or reduce tussal impulses, or both Aim to control rather than eliminate cough Uses:  dry nonproductive cough or if cough is unduly tiring, disturbs sleep or is hazardous(hernia, piles, cardiac disease, ocular surgery) Opioid antitussives Morphine : not suitable for its strong addicting and respiratory depressant property its congeners are the most effective antitussives

7. Opioid antitussives Codeine : opium alkaloid, similar but less potent than morphine More selective for cough centre; suppresses cough for 6 hours Acts via opioid receptors in brain as antitussive action can be blocked by naloxone. Side effect: Constipation,  respiratory depression & drowsiness Contraindicated in asthmatics; should be avoided in children Dose: 10–30 mg; children 2–6 years 2.5–5 mg, 6–12 years 5–10 mg. Ethylmorphine :  closely related to codeine; less constipating Dose: 10–30 mg TDS Pholcodine : no analgesic or addicting property Longer acting—acts for 12 hours; dose: 10–15 mg

8. Nonopioid antitussives Noscapine ( Narcotine ) : opium alkaloid of benzoisoquinoline series Depresses cough but no narcotic, analgesic or dependence Equipotent as codeine; useful in spasmodic cough Side effect: Headache and nausea Contraindication: Asthmatics can release histamine and produce bronchoconstriction. Dose: 15–30 mg, children 2–6 years 7.5 mg, 6–12 years 15mg

9. Nonopioid antitussives (Contd.) Dextromethorphan : synthetic central NMDA (N-methyl D-aspartate) receptor antagonist d-isomer- antitussive & l-isomer- analgesic Side effect:Dizziness, nausea, drowsiness; high doses hallucinations & ataxia Dose: 10–20 mg, children, 6–12 years 5–10 mg Chlophedianol : centrally acting antitussive with weak antihistaminic, anticholinergic and local anaesthetic properties Slow onset & duration longer Side effect: Dryness of mouth, vertigo, irritability. Dose: 20–40 mg.

10. Antihistamines H 1 antihistamines added to antitussive/expectorant Relief in cough due to Sedative action & reduce secretions by anticholinergic actions. Chlorpheniramine (2–5 mg), Diphenhydramine (15–25 mg) and Promethazine (15– 25 mg Bronchodilators Improves effectiveness of cough in clearing secretions by increasing surface velocity of airflow Useful  especially in individuals with bronchial hyperreactivity Given as FDCs as antitussive with a bronchodilator or with an antihistaminic