14drugs acting on respiratory system expectorants, respiratory stimulants
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This document discusses various drugs used for treating cough and facilitating removal of respiratory secretions. It describes antitussives/cough suppressants such as codeine, dextromethorphan and noscapine which act centrally to suppress cough reflex. It also discusses expectorants like potassium iodide, ammonium chloride and bromhexine which increase production or decrease viscosity of bronchial secretions to aid in coughing up mucus. The document provides details on mechanisms of action, uses, doses and side effects of these antitussive and expectorant drugs.
14drugs acting on respiratory system expectorants, respiratory stimulants
- 2. • Cough is a protective reflex that removes foreign material and secretions from the bronchi and bronchioles. • Coughing may be initiated either voluntarily or reflexively • Two types : – Productive cough( useful cough) – Unproductive cough ( useless cough)
- 3. Classification ANTITUSSIVES/COUGH SUPPRESSANTS a. Opiods and related drugs • • • • • Codeine Hydrocodone Pholcodeine Morphine Ethylmorphine EXPECTORANTS a. Directly acting: Sodium and potassium salts of iodine , citric acid or acetic acid , guaicol, tolu balsam, terpene hydrate, Guaiphenesin b. Reflexly acting : i) Saline expectorants : NH4Cl, NaHCO3 ii) Ipecacuanha syrup b. Non-opioids • Dextromethorphan • Caramiphene • Noscapine c. Mucolytics : c. Antihistamines • Chlorcyclizine • Diphenhydramine • promethazine Pharyngeal demulcents : Lozenges, cough drops , linctuses containing syrup, glycerine , liquorice i) ii) iii) Bromhexine Acetylcysteine Carbocisteine
- 4. Specific treatment approach of cough • Upper respiratory infection: antibiotics • Smoking / chronic bronchitis : cessation of smoking , avoidance of pollutants • Pulmonary tuberculosis : antitubercular drugs • Asthmatic cough: antiasthmatics • Postnasal drip due to sinusitis : antibiotic , nasal decongestants , H1 blockers • Gastroesophageal reflux : bed head elevation, light dinner , diet modification , drugs for PUD • ACE inhibitor associated cough: substitute by losartan, indomethacin , nifedipine
- 5. 1 . MORPHINE • It is an effective antitussive but it produces depression of respiratory centre and drug dependence .Hence it is not used at clinical level for antitussive. 2. CODEINE PHOSPHATE • It is centrally acting cough suppressant. MECHANISM OF ACTION • Depresses cough reflex by a direct depressant effect on cough centre . USES • Used for dry and painful cough. • Standard narcotic antitussive • Severe pain • Antispasmodic • Diarrhoea ADVERSE EFFECTS • • • • • • • Nausea Vomiting Constipation Addiction Drowsiness Respiratory depression In case of liver disease ,increased dose causes convulsions in children PRECAUTIONS • Prostatic hypertrophy • Hepatic disease CONTRAINDICATIONS • In bronchial asthma because it induces bronchospasm. • Children below 2 year
- 6. DOSE Mild to moderate pain Adult dose ::30-60mg every 4 hours ,to a maximum of 240mg daily Child dose:1-12 years:3mg/kg daily in divided doses Dry or painful cough Adult dose:15-30mg 3-4 times daily child dose:7.5-15mg 3-4 times daily
- 7. PHOLCODINE • It is semisynthetic derivative of codeine. • It is It is available as linctus and may be given to children ..It doesnot cause constipation and less liable to cause addiction as compared to codeine. • It is more potent than codeine . MECHANISM OF ACTIONS • Same as codeine USES • For dry and painful cough. ADVERSE EFFECTS • Nausea • Drowsiness
- 8. DEXTROMETHORPHAN • The antitussive activity of the drug is about equal to that of codeine.the drug produces no analgesia or addiction or CNS depression.And is also devoid of constipating actions. MECHANISM OF ACTION • Acts centrally to elevate the threshold for coughing. USES • Widely used anti tussive and is the constituent of many cough remedies. • Used for dry cough ADVERSE EFFECTS It occasionally causes • Drowsiness • Dizziness • Excitation • Mental confusion • GI disturbances CONTRAINDICATIONS • Liver disease DOSES • 10-20mg every 4hrs or 30mg every 6-8hrs
- 9. NOSCAPINE • It is as effective as codeine. • It has weak bronchodilator properties and stimulates the respiration. • IT is available as linctus and effect last for 4 hrs.It has no addicting,sedative and analgesic properties. ADVERSE EFFECTS Drowsiness and nausea DOSE Adult:15-30mg CONTRAINDICATIONS asthma
- 10. H1 antihistamines • Many H1 antihistamines have been added to antitussive/expectorant formulations .They afford relief in cough due to their sedative and anticholinergic actions but lack selectivity for the cough centre.They have no expectorant action,may even reduces secretions by anticholinergic actions.They have been specially promoted for cough in respiratory allergic states . • Chlorpheniramine:2-5mg • Diphenhydramine:15-25mg • Promethazine:15-25mg
- 11. Expectorants These are the drugs that facilitate removal of respiratory secretions by coughing. Mechanism of actions 1.sedative expectorants • They soothe inflamed respiratory mucosa by stimulating protective mucus secretions from secretory cells of respiratory airways. • Increase fluidity of sputum ,that helps in its expectoration by cough. 2.Stimulant expectorant • Stimulates healing and repair of chronically inflamed respiratory mucosa.
- 12. Cholinergic drugs • These act on the cholinergic receptors of the bronchi and increases bronchial secretions.these are not used clinically due to strong side effects. SIDE EFFECTS • • • Decrease heart rate Decrease force of contraction Decrease B.P Sodium and potassium salts of iodine • KI is active in increasing the volume and decreasing the viscosity of bronchial secretion. Being a bronchial gland irritant as well as gastric Irritant ,it directly and reflexly increases the bronchial secretions. SIDE EFFECTS • Unpleasant taste • Sneezing and conjuctival irritation resembling common cold • Skin rashes • Goiter and hypothyroidism • Acne Dose: 200-300mg Contraindications : Asthmatic patients
- 13. MECHANISM OF ACTION All these drugs except water irritate the gastric mucosa .Impulses goes to the vomiting centre and from there impulses are sent to bronchioles and bronchial secretion increases. DOSE Ammonium salts: 0.3-1gm ADVERSE EFFECTS: Nausea,vomiting
- 14. MUCOLYTIC EXPECTORANT: BROMHEXINE • Bromhexine is a mucolytic agent used in the treatment of respiratory disorders associated with viscid or excessive mucus • It reduces viscosity of bronchial secretions by depolymerization of mucopolysaccharides in ground substances of bronchial secretions and by liberating lysosomal enzymes resulting in thinning of the mucus. • Derived from Adhatoda vasica USES 1.to reduce sputum viscosity in cystic fibrosis 2.chronic asthma and bronchitis 3.productive cough DOSE Bromhexine: Carbocisteine: adult 8mg TDS Children:4mg BD adult -750mg TDS initially 1.5 g daily in divided doses ADVERSE EFFECTS Rhinorrhoea,lacrimation,skin rashes, GI irritation
- 15. PERIPHERAL ANTITUSSIVES MECHANISM OF ACTIONS They suppress cough reflex by decreasing the input of stimuli from cough receptors in respiratory passages. 1.DEMULCENTS They glutinously and soothingly coat pharynx. 2.STEAM INHALATION steam inhalation with tincture benzoin or menthol promotes secretion of protective mucus. 3.DRUGS WITH LOCAL ANAESTHETIC ACTIVTY Benzonatate reduce cough by depressing pulmonary stretch receptors.It also has a central cough suppressant effect. USES Demulcents :cough due to sore-throat and pharyngitis Steam inhalation :cough due to tracheo bronchitis.
- 16. Respiratory stimulants/ analeptics • Stimulate respiration and have resuscitative value in coma or fainting. • Situations in which analeptics are used : – – – – Respiratory depression due to Hypnotic drug poisoning Suffocation on drowning Apnoea in premature infants Failure to ventilate spontaneously after general anesthesia • Drugs : – – – – Doxapram Prethcamide Modafinil Reflex stimulants : ammonia, alcohol vapours
- 17. Doxapram • Mechanism of action – Acts by promoting excitation of central neurons , at low dose more selective for respiratory centre – Increases depth of respirations (tidal volume) by stimulating respiratory center in CNS; respiratory rate may increase slightly. – May elevate BP by increasing cardiac output, due to stimulation of carotid and aortic body chemoreceptors – Respiratory depression from opiates is reversed without affecting pain relief. • Indications: – Reversal of respiratory depression caused by anesthesia (other than muscle relaxants) or drug overdose; – temporary measure for acute respiratory failure in patients with COPD who are not undergoing mechanical ventilation. – Low doses of doxapram have been used in the treatment of apnea of prematurity when methylxanthines have failed.
- 18. • Adverse Reactions – Arrhythmias; tachycardia; increased BP; tightness in chest; chest pain; phlebitis. – Seizures; paresthesia; increased reflexes; disorientation; dizziness; involuntary movements. – Mydriasis. – Nausea; vomiting; diarrhea; desire to defecate. – Urinary incontinence and retention; elevation of BUN. – Hemolysis (with rapid infusion). – Laryngospasm; bronchospasm; rebound hypoventilation; cough; hiccoughs; dyspnea. – Flushing; feelings of warmth; sweating – Doxapram contains benzyl alcohol, which has been associated with fatal “gasping syndrome” in premature infants.
- 19. Route / dosage: • ADULTS: • Bolus IV injection 0.5 to 1 mg/kg (single dose not to exceed 1.5 mg/kg). Can be given as multiple IV injections q 5 min (not to exceed total dose of 2 mg/kg). • IV infusion Initial rate: 5 mg/min until satisfactory respiratory response is noted. Maintenance rate: 1 to 3 mg/min. Maximum total infusion dose is 4 mg/kg