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Uploaded byNeha Ansari
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Mechanism of Breathing and Drugs used in Treatment of Cough

This presentation explains the basic physiology of breathing, the process of mucus production in the respiratory tract, and the pharmacological management of cough. It begins with the mechanism of breathing, describing the roles of the diaphragm and intercostal muscles during inspiration and expiration. The presentaton then discusses how mucus is produced by goblet cellsand submucosal glands, its protective functions, and the role of cilia in clearing mucus from the airways. The final section focuses on the treatment of cough, including the classification, mechanism of action, therapeutic uses, and examples of commonly used drugs such as antitussives, expectorants, mucolytics, and bronchodilators.

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MECHANISM OF BREATHING INSPIRATION AND EXPIRATION NEHA ANSARI B.PHARM 3RD YEAR ASHA PHARMACY COLLEGE
MECHANISM OF BREATHING  Breathing involves two stages : Inspiration during which atmospheric air is drawn in and expiration by which the alveolar air is released out.
INSPIRATION  The process of intake of atmospheric air is known as inspiration. It is an active process.  In the process of inspiration, there would be a contraction of muscles attached to the ribs on the outer side which pulls out the ribs and results in the expansion of the chest cavity.  Later, the diaphragm, contracts, moves downwards and expands the chest cavity resulting in the contraction of the abdominal muscles.  The expansion of the chest cavity produces a partial vacuum which sucks air into the lungs and fills the expanded alveoli.
MECHANISM OF INSPIRATION  When the volume of the thorasic cavity increases and the air pressure decreases, inspiration takes place.  Contraction of external intercostal muscles increases the volume of the thorasic cavity.  Contraction of the diaphragm further increases the size of the thorasic cavity. Simultaneously, the lungs expands.  With the expansion of the lungs, the air pressure inside the lungs decreases.  The pressure equalizes and the atmospheric air rushes inside the lungs.
INHALATION Brain respiratory center activated ( Medulla & Pons) Nerve signals sent through phrenic & intercostal muscles contract. Diaphragm contracts – moves downward External intercostal muscles contracts Rib cage moves upwards & outwards Volume of Thorasic cavity increases & pressure in alveoli decreases Air flows into lungs
EXPIRATION  The process of exhaling carbon dioxide is called expiration. It is a passive process.  The expiration process is considered once after the gaseous exchange occurs in the lungs and the air is expelled out.  During this process, muscles attached to the ribs contract, the muscles of the diaphragm and the abdomen relax which leads to a decrease in the volume of the chest cavity and increases the pressure of the lungs, causing the air in the lungs to be pushed out through the nose.
MECHANISM OF EXPIRATION  It occurs when the size of the thorasic cavity decreases and the air pressure increases.  Now the external intercostal muscles relax and the internal intercostal muscles contract.  As a result, the ribs are pulled inwards and the size of the thorasic cavity is reduced.  The diaphragm is relaxed and the lungs get compressed.  Consequently, the pressure increases and the air is forced outside.
EXHALATION Internal intercostal muscles contracts External intercostal muscles relax ,Diaphragm relax Rib cage moves downwards & inwards Volume of thorasic cavity decreases Pressure in alveoli increase Air moves out.
MUCUS  Mucus is a thick, slippery secretion produced by submucosal glands and goblet cells, located in the airway epithelium.
COMPOSITION OF MUCUS Mucus is mostly water, plus :  Mucins ( Glycoproteins ) give thickness and elasticity  Electrolytes  Antibodies ( IgA )  Enzymes  Trapped particles ( dust, microbes ).
HOW MUSUS SECRETS IN LUNGS ?  Production mechanism : Goblet Cells in the surface epithelium and glands in the large airways produce mucins, which are released via exocytosis.  Structure : It forms a two - layer system : a high - viscosity gel layer on top and a low – viscosity, watery layer below, which helps the cilia beat properly.
 Regulation : Secretion is controlled by neurotransmitters and inflammatory mediators. - Infections, allergies and irritants like smoke trigger increased production.  Pathology : Conditions like COPD, Asthma and cystic fibrosis can cause excessive , thick mucus production ( hypersecretion ) that overwhelms the cilia , leading to coughing and breathing difficulties.
 Clearance : Tiny hair - like structures called cilia constantly beat in a coordinated way. - They push the mucus upward toward the throat. - This is called the mucocilliary escalator. FUNCTIONS -Traps dust, germs , smoke, bacteria, viruses and pollutants , so they don’t reach deep lung tissue.
Drugs Used in Treatment of Cough EXPECTORANTS & ANTITUSSIVES
COUGH  Cough is a protective reflex, its purpose being expulsion of respiratory secretions or foreign particles from air passages.  It occurs due to stimulation of mechano - or chemoreceptors in throat, respiratory passages or stretch receptors in the lungs. Cough may be useful or useless.  Useless ( nonproductive ) cough should be suppressed.  Useful ( productive ) cough serves to drain the airway, its suppression is not desirable, may even be harmful, except if the amount of expectoration achieved is small compared to the effort of continuous coughing.
MECHANISM OF COUGH Stimulation of mechano – or chemoreceptors ( throat, respiratory passages or stretch receptors in lungs ) Afferent impulses to cough center (medulla ) Efferent impulses via parasympathetic & motor nerves to diaphragm, intercostal muscles & lung Increased contraction of diagrammatic, abdominal & intercostal (ribs) muscles noisy expiration ( cough )
DRUGS FOR COUGH
PHARYNGEAL DEMULCENTS  Pharyngeal demulcents sooth the throat and reduce afferent impulses from the inflamed/irritated pharyngeal mucosa, thus provide symptomatic relief in dry cough arising from throat. Lozenges Syrups Glycerine Liquorice
LOZENGES  Throat lozenges are medicated, dissolvable tablets designed to soothe sore throats, reduce irritation and suppress coughs by increasing saliva and delivering ingredients like menthol, honey, or antiseptics directly to the throat.
EXPECTORANTS  Expectorants are the drugs that help in removing sputum from respiratory tract either by increasing fluidity of sputum or increasing the volume of fluid. That have to be expel from the respiratory tract by coughing.  These are the agents which enhance the secretion of sputum from trachea, bronchi or lungs and hence they are used in treatment of cough.
CLASSIFICATION OF EXPECTORANTS  Based on MOA they are categorized into two types: 1. Secretion Enhancer Pot. Citrate Pot. iodide 2. Mucolytics Bromhexine Acetylcystein
SECRETION ENCENCER Expectorants Increase bronchial secretion or decreases viscosity of cough Easy removal of cough
MUCOLYTICS These agents dissolve thick mucous Helps to relieve respiratory difficulties By breaking disulfide bonds in mucopolysaccharides Decreases the viscosity of secretions Easy expulsion of mucous
ANTITUSSIVES  Antitussives are drugs that suppress coughing, possibly by reducing the activity of the cough center in the brain.  Antitussives agents are used to relieve dry cough.
CLASSIFICATION OF ANTITUSSIVES  1.Opioids: Ex- Codeine, Ethyl morphine, pholcodine  2.Nonopiods: Ex- Noscapine, Dextromethorphan  3.Antihistaminics: Ex- Chorpheniramine  4.Adjuvant antitussives/Bronchodilators: Ex- Salbutamol, Terbutaline
OPIOIDS  Opioids suppress the cough reflex by acting on the cough center in the medulla. CODEINE  Selectively suppress cough center in medulla oblongata.  Pharmacokinetics : 1.Well absorbed from oral and injection. 2.10% converted to morphine through demethylation.
NONOPIOIDS  Suppress the cough reflex by numbing the stretch receptors in the respiratory tract and preventing the cough reflex from being stimulated.
ANTIHISTAMINICS  It is a sedative and have anticholinergic action.  They have lack selectivity for cough center.
ADJUVANT ANTITUSSIVES/BRONCHODILATORS  Bronchospasm can induce or aggravate cough. Stimulation of pulmonary receptors can trigger both cough and bronchoconstriction, especially in individuals with bronchial hyper reactivity.  Bronchodilators relieve cough in such individuals and improve the effectiveness of cough in clearing secretions by increasing surface velocity of airflow during the act of coughing.
SALBUTAMOL Salbutamol Activates beta-2 receptor in bronchial smooth muscle Activates adenyl cyclase activity increase cAMP smooth muscle relaxation Bronchodilation
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