The document discusses drugs that act on the respiratory system. It describes the main functions of the respiratory system as delivering oxygen to cells, eliminating carbon dioxide from the body, and regulating blood pH. It then discusses various components of lung function including ventilation, distribution, diffusion, and perfusion. It provides details on common respiratory drugs like bronchodilators, corticosteroids, leukotriene receptor antagonists, expectorants, mucolytics, antitussives, and methylxanthines. It also covers adverse effects and guidelines for treating conditions like asthma and acute bronchitis.

1. BHOLE NATH, Lecturer Dept. of Pharmacy LINCOLN UNIVERSITY COLLEGE MALAYSIA DRUGS ACTING ON THE RESPIRATORY SYSTEM

4. VENTILATION Movement of air to and from the lungs DISTRIBUTION Air entering lungs are distributed to all parts including the alveoli DIFFUSION Oxygen from the inspired air diffuses through the walls of the alveoli to the blood capillaries surrounding the alveoli-similarly carbon dioxide diffuses in opposite direction PERFUSION Blood with high concentrations of carbon dioxide and low in oxygen is pumped to the pulmonary arteries by the right ventricle and after diffusion, the arterial blood is returned to the left atrium by the pulmonary veins COMPONENTS OF LUNG FUNCTION

5. PASSAGE OF OXYGEN AND CARBON DIOXIDE SOURCE OF OXYGEN – INSPIRED AIR SOURCE OF CARBON DIOXIDE-ALVEOLI- Following diffusion from the blood due to metabolism in the body. PATHWAY FOR THE GASES: PHARYNX LARYNX-TRACHEA BRONCHI BRONCHIOLES ALVEOLI VENTILATION

6. atmosphere o oxygen c Carbon dioxide Right heart-arteries Left heart-arteries Systemic circulation oxygen Carbon dioxide

8. Mucosal surface lining respiratory tract Impulses relayed via vagus Cough centre in brain Efferent's diaphragm glottis muscles of chest and abdomen COUGH – FORCED EXPIRATION AGAINST A CLOSED GLOTTIS WHICH SUDDENLY OPENS TO EXPEL AIR AND UNWANTED MATERIAL FROM THE RESPIRATORY TRACT MAY BE VOLUNTARY OR INVOLUNTARY

9. Mucokinetics are a class of drugs which aid in the clearance of mucous from the airways, lungs , bronchi , and trachea . Such drugs can be further categorized by their mechanism of action. expectorants mucolytic agents In general, clearance ability is hampered by bonding to surfaces (stickiness) and by the viscosity (thickness) of mucous secretions in the lungs . In turn, the viscosity is dependent upon the concentration of mucoprotein in the secretions.

10. Expectorants and mucolytic agents are different types of medication, yet both intend to promote drainage of mucus from the lungs. An expectorant (from the Latin expectorare , to expel from the chest) works by signaling the body to increase the amount or hydration of secretions, resulting in more yet clearer secretions and as a byproduct lubricating the irritated respiratory tract. One expectorant guaifenesin is commonly available in many cough syrups. Sometimes the term "expectorant" is incorrectly extended to any cough medicine, since it is a universal component. A mucolytic agent is an agent which dissolves thick mucus and is usually used to help relieve respiratory difficulties. It does so by dissolving various chemical bonds within secretions, which in turn can lower the viscosity by altering the mucin-containing components.e.g ,Bromohexine, Acetyl Cysteine

11. A cough medicine (or linctus , when in syrup form) is a medicinal drug used in an attempt to treat coughing and related conditions. For dry coughs, treatment with cough suppressants ( antitussives ) may be attempted to suppress the body's urge to cough. However, in productive coughs (coughs that produce phlegm ), treatment is instead attempted with expectorants (typically guaifenesin , in most commercial medications) in an attempt to loosen mucus from the respiratory tract . These are the drugs that act in the CNS to the threshold of cough center or act peripherally in the respiratory tract to reduce tussal impulses. NOTE: It is only for dry unproductive coughs

12. ANTITUSSIVE/ COUGH SUPPRESSANTS Unproductive distressing cough- central cough depressants e.g. pholcodine, dextromethorphan Productive cough-do not use cough suppressants Use expectorants and mucolytics Expectorants-act by increasing the volume of secretions in respiratory tract so that they may be more easily removed by ciliary action and coughing e.g.ammonium salts, guaphenesin, ipecacuanha Mucolytics- considered to affect sputum viscosity e.g.acetylcysteine, bromhexine, carbocisteijne, methyl cysteine

17. DORNOSA ALFA ACTS AS A MUCOLYTIC BY HYDROLYSING DNA THAT HAS ACCUMULATED IN THE SPUTUM FROM DECAYING NEUTROPHILS USED AS A NEBULIZING SOLUTION IN PATIENTS WITH CYSTIC FIBROSIS

19. Adrenergic agonists All adrenergic agonists have variable alpha and beta receptor affinity. Due to the distribution of alpha and beta receptors- non-selective beta receptor agonists such as isoprenaline or mixed alpha and beta receptor agonists such as adrenaline are more likely to produce cardiovascular side effects than similarly administered selective beta agonists. THEREFORE DRUGS WITH PREFERENTIAL AFFINITY FOR BETA 2 RECEPTORS PROVIDE MORE EFFECTIVE BRONCHODILATION WITH FEWER SIDE EFFECTS. A possible exception may be with the treatment of acute allergic bronchospasm. The M-2 receptor-mediated inhibition of cholinergic bronchospasm may be helpful. For this reason, the use of an adrenergic agent with both alpha 2 and beta 2 agonist activity may be beneficial in the peracute management of allergic bronchospasm. Due to risks associated with administering systemic non-selective adrenergic agonists to a hypoxic and already tachycardic patient, it is preferable for them to be administered by inhalation. Selective beta 2 agonists- lead to rapid and effective pulmonary beta 2 receptor activation with low systemic drug concentrations by inhalation of small doses of the drug in aerosol form.

21. Widely available at present- codeine phosphate and hydrocodone. Codeine has a high oral-parenteral potency with oral administration providing around 60% of its parenteral efficacy. Once absorbed, codeine is metabolized by the liver . Inactive metabolites excreted predominantly in the urine. In man approximately 10% of administered codeine is demethylated to form morphine -and both free and conjugated forms of morphine can be found in the urine of patients receiving therapeutic doses of codeine. In man, codeine's plasma half-life is around 2 to 4 hours. Codeine phosphate is contained in numerous "over the counter" analgesic preparations as well as in 30 and 60mg tablets which have restricted scheduling. Hydrocodone is generally marketed in combination with homatropine as both an elixir and tablet formulations. The addition of homatropine is designed to enhance any reduction in respiratory secretions, which may come about as a result of the administration of hydrocodone. BENZONATATE Cough suppressant believed to act both centrally and peripherally. Related to amethocaine ( a local anaesthetic) and therefore has a local anaesthetic action on the mucosa. . OPIOID ANTITUSSIVES

23. DEMULCENTS INDIRECTLY ACTING COUGH SUPPRESSANTS ? MODE OF ACTION POSSIBLY BY PROVIDING A PROTECTIVE COATING OVER THE SENSORY RECEPTORS IN THE PHARYNX EXAMPLES- GLYCEROL, HONEY, LIQUORICE AND SUCROSE SYRUPS

26. ACUTE BRONCHITIS TREATMENT USUALLY NOT REQUIRED IN PREVIOUSLY HEALTHY PATIENTS BELOW AGE 60 EXACCERBATION OF COPD-START WITH DOXYCYCLINE 200MG OD -SECOND LINE-AMOXICILIIN (OR CO-AMOXICLAV) BRONCHIECTASIS-CO-AMOXICLAV 1.2 G TDS IV OR IF AVAILABLE PIPERICILLIN + TAZOBACTAM 4.5 G TDS CYSTIC FIBROSIS- CIPROFLOXACIN 500MG BD ORALLY OR 400MG BD IV IF PSEUDOMONAS IS SUSPECTED Adapted from Pocket Prescriber

28. SALBUTAMOL BETA 2 AGONIST- SHORT ACTING ACTIONS: 1. DILATES BRONCHIAL SMOOTH MUSCLE 2. RELAXES UTERINE SMOOTH MUSCLE 3.INHIBITS MAST-CELL MEDIATOR RELEASE BEWARE USE -IN CARDIO-VASCULAR DISEASE Esp. arrhythmias-susceptibility to increased QTc - DIABETES MELLITUS- MAY INCREASE RISK OF DIABETIC KETO-ACIDOSIS - MAY INCREAE THYROXINE LEVELS SIDE EFFECTS- FINE TREMOR, HEADACHE, NERVOUSNESS INCREASE IN HEART RATE, PALPITATIONS, ARRHYTHMIAS DECREASE IN SERUM POTASSIUM MUSCLE CRAMPS Prolonged treatment -? Increased risk of glaucoma