Treatment of cough By : Dr. Mahmoud A. Naga

cough Def. Cough is a useful physiological protective mechanism that clears respiratory passages of foreign material and excess secretions. Cough reflex: complex, involve central and peripheral nervous systems as well as mucosa & smooth muscle of the bronchial tree. irritation of bronchial mucosa causes bronchoconstriction, which in turn, stimulates cough receptors (specialized type of stretch receptor) located in the tracheobronchial passages.

causes of cough 1. Resp. dis. 2. Non Resp. dis. Common cold, Upper/lower respiratory tract infection Allergic rhinitis Acute & Chronic bronchitis Pulmonary tuberculosis Asthma Pneumonia Bronchiectasis Smoking, dust inhalation Congestive heart failure Gastroesophageal reflux Use of drugs (e.g. ACE inhibitors) 1. Resp. dis. 2. Non Resp. dis.

Types & Treatment of cough 1. According onset & duration A. Acute cough =lasting<3 weeks B. Chronic cough =lasing >8 weeks

non productive = useless 2. According presence of sputum 1- Wet cough = productive = useful 2- Dry cough = non productive = useless * remove secretions from resp. tract * useful & should be encouraged by Mucokinetic drugs: 1- expectorants 2- mucolytics * It is suppressed only if 1- exhaust patient specially elderly 2- dangerous to patient e.g. after eye surgery * not useful & annoy patient * Should ttt by cough suppressants = Antitussive N.B.: Antihistamines could be used in some cases of cough or added to cough mixures why?

A. Central antitussives Def. → drugs that reduce the frequency &/or intensity of dry cough. Central & peripheral A. Central antitussives * Source → opioid derivatives that have antitussive effect in doses lower than those required for pain relief with minimum analgesic, narcotic, and addictive properties than morphine. * Action → inhibit cough center in the medulla (brain stem) * Uses → Acute or chronic dry cough * Types →

1-Narcotic antitussives 2- Non-narcotic antitussives Codeine was considered gold standard ttt for cough suppression, but this position is questioned now. Studies found no effect in some cases of cough specially in children * has some analgesic & narcotic effect in large dose * Side effects → من اسمه 1- Co → Constipation 2- D→ Dryness of mucosa with thick sputum Decrease Cilliary movement Dysphoria انزعاج & fatigue Depression of R.C. in high doses. Dependence if used for long duration → addiction & Drug abuse 3- N → Nausea, vomiting Dextromethorphan Selective central antitussive with 1. Effective cough suppressant but Weaker than codeine 2. no or less analgesic & less narcotic 3. Less & rare S.E. than codeine (enumerate)

B. Peripheral antitussives Demulcents (Throat & Pharyngeal ) E.g. lozenges (cough drops, glycerine, liquorice, honey, menthol, may add local anathetic) Provide symptomatic relief in dry cough arising from throat (sore throat) or pharynx (pharyngitis) * Action → form gelatinous coat on the inflamed mucosa → protective soothing effect that reduces afferent impulses from inflamed/irritated pharyngeal mucosa * Menthol stimulate mucous secretion that cover cough receptor

2) Mucokinetics Drugs act peripherally on the lung to eithrer; 1. Increase bronchial secretion (Expectorants) OR 2. Decrease its viscosity and facilitates its removal by coughing (Mucolytics) This will make cough less irritating & more productive

Expectorants Directly acting: E.g., * Guaifenesin (glyceryl guaiacolate) oral, single or in combination, Increase volume & reduce viscosity of secretions in lung * Na+ & K+ citrate or acetate, increase bronchial secretion by salt & alk. effect b) Reflexly acting E.g., Ammonium salt cause gastric irritation leading to vagal reflex that increase bronchial secretions + sweating

Mucolytics i) Bromhexine (oral & injection) & Ambroxol (oral) Help expectoration by liquefy the viscous lung secretions i) Bromhexine (oral & injection) & Ambroxol (oral) a) Thinning & fragmentation of mucopolysaccaride fibers b) ↑ volume & ↓ viscosity of sputum ii) Acetylcysteine (oral & inhalation) * Opens disulfide bond in mucoproteins of sputum =↓ viscosity * Uses: Cystic fibrosis, bronchitis, COPD * Adverse effects: irritative in GIT & lung (inhaled cysteine) Nausea, vomiting, bronchospasm in bronchial asthma باك مذيب المخاط B A C

Antihistamines * Antihistamines aren't technically considered cough medicines, but they may be useful if an allergy is the cause as in hay fever or allergies with runny nose, sneezing and watery eyes in addition to cough. It block the histamine action that causes the allergy. * Usually use sedating antihistamines (e.g. chlorpheniramine) due to sedative anticholinergic actions that produce relief from cough, decrease secretions, bronchodilation without effect on cough centre * May be used alone or usually added to antitussives/expectorant formulation