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Anti-tussives
- 2. COUGH-SUPPRESSANTS Cough is aprotective reflex. It expels secretions or foreign particles from air passages. It occurs due to stimulation of mechano, or chemo receptors of throat, respiratory tract and stretch receptors in lungs. It is of two types- (1) Non-productive cough or useless cough or cough without sputum (2) Productive cough or useful cough or cough with sputum Factors responsible for producing cough 1. Irritants 2. Pollutants 3. Dust 4. Smoke 5. Upper respiratory infections 6. Foreign particles 7. Drugs and chemicals 8. Pathophysiological conditions- a. Asthma b. Lung infections or lung cancer c. Tuberculosis d. Pleural infections e. Chronic bronchitis Drug therapy for Cough Classification of Drugs (I) Expectorants (II) Anti-tussives (III) Pharyngeal demulcents (II) Anti-tussives Antitussives: These are the drugs that act on the CNS to raise the threshold of cough or act peripherally in the respiratory tract to reduce tussal impulses or both actions. They do not cure the cough only control, useful in dry, irritating, unproductive cough or if cough disturbs sleep or hazardous in the case of hernia, piles, cardiac diseases, ocular surgery. They are also known as cough center suppressants.
- 3. Classification of Anti-tussives (A)Opioids (acts on opioid receptors in brain. They causes constipation, respiratory depression & drowsiness at higher doses) • Benzonatate • Codeine • Ethylmorphine • Levoproxyphene • Methadone • Morphine • Naloxone • Pholcodiene (B) Non-opioids • Caramiphen • Carbetapentane • Chlophedianol • Dextromethorphan • Noscapine • Oxiladine • Pipazethate (C) Antihistamines • Chlorpheniramine • Diphenhydramine • Promethazine • Pseudoephedrine • Fexofenadine (III) Pharyngeal demulcents They not ANTI-TUSSIVES, producing soothing action on throat directly and by increasing saliva secretion. They only provides symptomatic relief of dry cough. • Cough drops • Glycerin • Liquorices • Linctuses containing syrups • Lozenges
- 4. PROTOTYPE DRUGS CODEINE It isan opioid drug that depresses cough centers and used in the form of codeine linctus. Pharmacological actions Similar to morphine with low addiction liability and does not dressed respiration as morphine, suppressed cough centers. Mechanism of action To raise the threshold of cough and to reduce tussal impulses or both actions, useful in dry unproductive cough. ADME Well absorbed after oral administration and have long duration of action. Interactions Antihistamines and ammonium chloride potentiate anti-cough action Contra-indicated in- Asthmatic conditions Dose 10-30mg/TDS Adverse effects Nausea Vomiting Constipation Dizziness Drowsiness Dependence Uses It is preferred in following cases- Dry or unproductive cough Diarrhea Analgesia PIPAZETHATE It is a derivative of phenothiazine, used in dry cough. Dose 40-80mg/day Uses It is preferred in the following cases- Dry cough as antitussive Pain as analgesic As sedative agent
- 5. CHLORPHENIRAMINE It is anantihistaminic agent, used in common cold and allergic conditions. Pharmacological actions Inhibition of flare, itching and weal Relaxes smooth muscles of various organs Reduces edema by suppressing capillary permeability Mechanism of action-Competitively produces reversible blockade of H1 histamine receptors. ADME-Well absorbed from GIT after oral administration and metabolized in liver by hydroxylation. Interactions-Potentiation of action of CNS depressants Contra-indicated in- Renal dysfunctions Hepatic disorders Dose=2-4mg/orally Adverse effects Blurred vision Constipation Dermatitis Diarrhea Dizziness Drug fever Dryness of mouth Dysuria Epigastric distress Impotence Nausea Photoallergy Sedation Tightness of chest Tinnitus Urinary retention Vertigo Vomiting Wheezing Uses It is preferred in the following cases- Cough Common cold Anaphylactic shock Insect bite Allergic conditions