Treatment of cough Modified By :ISRAA

cough Cough is a useful physiological mechanism that serves to clear the respiratory passages of foreign material and excess secretions. It should not be suppressed indiscriminately. There are, however, many situations in which cough does not serve any useful purpose but may, instead only annoy the patient or prevent rest and sleep.

Cough Chronic cough can contribute to fatigue, especially in elderly patients, in such situations the physicians should use a drug that will reduce the frequency or intensity of the coughing. Cough reflex is complex, involving the central and peripheral nervous systems as well as the smooth muscle of the bronchial tree.

Cough It has been suggested that irritation of the bronchial mucosa causes bronchoconstriction, which in turn, stimulates cough receptors ( which probably represent a specialized type of stretch receptor) located in the tracheobronchial passages.

Types of cough A)Acute cough =lasting<3 weeks B)Chronic cough =lasing >8 weeks Cough may be i) Un productive (dry) cough OR ii) Productive cough (sputum)

Most common causes of cough Common cold, Upper/lower respiratory tract infection Allergic rhinitis Smoking Chronic bronchitis Pulmonary tuberculosis Asthma Gastroesophageal reflux Pneumonia Congestive heart failure Bronchiectasis Use of drugs (e.g., Angiotensin-converting enzyme inhibitors)

Treatment of Cough Antitussives (cough center suppressants) Expectorants Mucolytics Antihistamines Pharyngeal Demulcents

1) Antitussive Antitussive drugs act by ill defined effect in the brain stem, depressing an even more poorly defined “cough center”. All opioid narcotic analgesic have antitussive narcotic analgesic in doses lower than those required for pain relief They have minimum analgesic and addictive properties Newer agent that only act peripherally on sensory nerves in bronchi are being assessed

i) CODIENE It is the gold standard treatment for cough suppression It decreases the sensitivity of cough center in the CNS to peripheral stimuli, decrease the mucosal secretion which thicken the sputum, and inhibit ciliary activity These therapeutic effect occur at doses lower than those required for analgesia but still incur common side effect like constipation, dysphoria, and fatigue, in addition to addiction potential

ii) DEXTROMETHORPHAN Is a synthetic derivative of morphine that suppresses the response of the central cough center It has no analgesic effect, has low addictive profile, but may cause dysphoria at higher doses Has significantly better side effect profile than codeine and has been demonstrated to be equally effective for cough suppression

2) Expectorants (Mucokinetics) Act peripherally Increase bronchial secretion OR Decrease its viscosity and facilitates its removal by coughing Loose cough ► less tiring & more productive

Classification of Expectorants Classified into a) Directly acting E.g., Guaifenesin (glyceryl guaiacolate), Na+ & K+ citrate or acetate, b) Reflexly acting E.g., Ammonium salt

Directly acting expectorants i) Sodium & potassium citrate or Acetate They increase bronchial secretion by salt action ii) Guaifenesin Expectorant drug usually taken by mouth Available as single & also in combination MOA=Increase the volume & reduce the viscosity of secretion in trachea & bronchi

Reflexly acting expectorants Ammonium salts Gastric irritants = reflex increase in bronchial secretions + sweating

3) Mucolytics Help in expectoration by liquefy the viscous tracheobronchial secretions E.g., Bromhexine, Acetyl cysteine, i) Bromhexine Synthetic derivative of vasicine MOA of Bromhexine a) Thinning & fragmentation of mucopolysaccaride fibers b) ↑ volume & ↓ viscosity of sputum

3) Mucolytics ii) Acetylcysteine Given directly into respiratory tract MOA of acetylcysteine: Opens disulfide bond in mucoproteins of sputum =↓ viscosity Uses: Cystic fibrosis Onset of action quick---used 2-8 hourly Adverse effects: Nausea, vomiting, bronchospasm in bronchial asthma

4) Antihistamines Added to antitussives/expectorant formulation Due to sedative anticholinergic actions produce relief from cough but lack selectivity for cough center No expectorant action = ▼ secretions (anticholinergic effect) Suitable for allergic cough E.g., Chlorpheniramine and diphenhydramine

5) Pharyngeal demulcents Soothe the throat (directly & also by promoting salivation Reduces afferent impulses from inflamed/irritated pharyngeal mucosa Provide symptomatic relief in dry cough arising from throat E.g. lozenges, cough drops, glycerine, liquorice, honey

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