2coughDef.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 wellas 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.
3causes of cough 1. Resp. dis. 2. Non Resp. dis. Common cold, Upper/lower respiratory tract infectionAllergic rhinitisAcute & Chronic bronchitisPulmonary tuberculosisAsthmaPneumoniaBronchiectasisSmoking, dust inhalationCongestive heart failureGastroesophageal refluxUse of drugs (e.g. ACE inhibitors)1. Resp. dis.2. Non Resp. dis.
4Types & Treatment of cough 1. According onset & duration A. Acute cough =lasting<3 weeks B. Chronic cough =lasing >8 weeks
5non productive = useless 2. According presence of sputum1- Wet cough =productive = useful2- Dry cough =non productive = useless* remove secretions from resp. tract* useful & should be encouraged byMucokinetic drugs:1- expectorants2- mucolytics* It is suppressed only if1- exhaust patient specially elderly2- dangerous to patient e.g. aftereye surgery* not useful & annoy patient* Should ttt by coughsuppressants= AntitussiveN.B.: Antihistamines could be used in some cases of cough oradded to cough mixures why?
6A. Central antitussives Def. → drugs that reduce the frequency &/orintensity of dry cough. Central & peripheralA. 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 →
71-Narcotic antitussives 2- Non-narcotic antitussives Codeinewas 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 اسمه1- Co → Constipation2- D→ Dryness of mucosa with thick sputumDecrease Cilliary movementDysphoria انزعاج & fatigueDepression of R.C. in high doses.Dependence if used for long duration→ addiction & Drug abuse3- N → Nausea, vomitingDextromethorphanSelective central antitussivewith1. Effective cough suppressant but Weaker than codeine2. no or less analgesic &less narcotic3. Less & rare S.E. than codeine (enumerate)
8B. 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 afferentimpulses from inflamed/irritated pharyngeal mucosa* Menthol stimulate mucous secretion that cover cough receptor
92) Mucokinetics Drugs act peripherally on the lung to eithrer; 1. Increase bronchial secretion (Expectorants)OR2. Decrease its viscosity and facilitates itsremoval by coughing (Mucolytics)This will make cough less irritating & more productive
10Expectorants 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. effectb) Reflexly acting E.g., Ammonium saltcause gastric irritation leading to vagal reflex that increase bronchial secretions + sweating
11Mucolytics i) Bromhexine (oral & injection) & Ambroxol (oral) Help expectoration by liquefy the viscous lung secretionsi) Bromhexine (oral & injection) & Ambroxol (oral)a) Thinning & fragmentation of mucopolysaccaride fibersb) ↑ volume & ↓ viscosity of sputumii) 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 asthmaباك مذيب المخاطB A C
12Antihistamines* 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