These are drugs which increase bronchial secretion or reduce its viscosity, facilitating its removal by coughing. They are believed to 'loosen' cough which becomes less tiring and more productive. Directly acting : Sodium & Potassium citrate or acetate, Potassium iodide, Guaiacol, Guaiphenesin, balsum of Tolu, Vasaka, Terpin hydrate. Reflexly acting : Ammonium chloride or carbonate, Potassium iodide, Ipecacuanha, Scilla. Mucolytics : It induces then copious secretion. It depolymarises mucopolysaccharides directly as well as by liberating lysosomal enzymes-network of fibres in tenacious sputum is broken. Bromhexine, Acetyl cysteine, Pancreatic Dornase. Anti tussives : These are drugs that act in the CNS to raise the threshold of cough centre or act peripherally in the respiratory tract to reduce tussal impulses, or both these actions. Antitussives should be used primarily for dry unproductive cough or if cough is unduely tiring or hazardous (hernia, piles, cardiac disease, ocular surgery). Codeine, Pholcodeine, Ethylmorphine, Morphine, Noscapine, Dextromethorphan, Carbetapentane. Oxeladin. Chlophendianol, Pipazethate. Antihistamines : They afford relief in cough due to their sedative and anti cholinergic actions, but lack selectively for the cough centre.
