emetic and antiemetic drugs.pptx

it describes different emetics and anti emetic drugs

1. PHARMACOLOGY Presentation on: Drug affecting gastrointestinal tract: Emetics and antiemetics Group 6 [pharmacy department] By tujar kaso(b pharm)

2. Emetics emetics are drugs that produce or induce emesis/vomiting. MECHANISM OF EMESIS/VOMITING emesis is the forceful expulsion of the contents of the stomach via the mouth or sometimes through the nose. the vomiting reflex is stimulated by two centers in the medulla vomiting center chemoreceptor trigger zone(CTZ)

3. Haw CTZ is stimulated? tactile stimulation of the back of the throat, a reflex to get rid of something that is too big or too irritating to be swallowed. excessive stomach distention. Increase intercranial pressure by direct stimulation Stimulation of the vestibular receptor in the inner ear intense pain fiber stimulation direct stimulation by varies chemicals, including fumes, certain drugs, and debris from cellular death

4. Classification of emetics STIMULANTS OF CTZ apomorphine morphine IRRITANTS OF GASTRIC MUCOSA Mustard sodium chloride BOTH CTZ STIMULANT AND IRRITANT EFFECT ipecacuanha digitalis

5. APOMORPHINE given through subcutaneously or through intramuscular -6mg causes vomiting within 15 min in hypertensive individual, however ,even a subtherapeutic dose may elicit sever emesis and collapse vomiting is often accompanied by sedation it should not be used if respiration is depressed larger doses often produce restlessness, tremor, occasionally convulsion sometimes may cause hypotension, syncope and coma

6. MUSTARD it is household remedy to induce vomiting volatile oil dose-1teaspoonful with water formed as a result of a reaction between a glycoside and an enzyme in the presence of water SODIUM CHLORIDE: given orally Withdraw fluids from the cells lining the stomach thus causes irritation which reflex emesis.

7. Ipecacuanha(Emetine) act by irritating gastric mucosa as well as through CTZ dried root of cephalis ipecacuanha contains emetine commonly available as syrup to induce emesis at a dose of: adults-15-20ml children- 10-15ml infant-5ml takes 15 min or more for the effect.

8. Emetics-contraindication ALL EMETICS CONTRAINDICATED IN: corrosive(alkali, acid) poisoning CNS stimulant drug poisoning kerosine(petroleum) poisoning unconscious patient

9. Antiemetics antiemetics are drugs that can prevent vomiting/emesis.

10. CLASSIFICATION prokinetics metochlorpramide domperidone antimuscarinic hyoscine meclozine antihistamine cyclizine promethazine(Phenergan)

11. 4. Neuroleptics Cyclizine Promethazine(Phenergan) 5. 5-HT3 antagonists Ondansetron granicetron

12. prokinetics these drugs which promote gastrointestinal motility and quicken gastric emptying drug available: metochlorpramide domperidone mechanism of action of prokinetic drug D2 antagonist 5-HT4 agonism 5HT3 antagonism

13. metoclopramide introduced in early 1970s as a “gastric hurrying agent” widely used antiemetic it has both central and peripheral effect: central-block the dopaminergic receptor peripheral- increased gastric emptying at a dose of-5-10mg

14. Interaction: hastens absorption of many drugs: Aspirin diazepam etc. facilitate the gastric emptying reduced absorption of digoxin adverse effect: sedations, dizziness, diarrhea, muscle dystonia long term use can cause parkinsonism, galactorrhea and gynecomastia

15. domperidone D2 antagonist chemically related to haloperidol but pharmacologically related to metoclopramide has lower ceiling antiemetic and prokinetic action poorly crosses BBB rare extra pyramidal side effect given with lavodo or bromocriptine to counteract their dose limiting emetic action absorbed orally, but bioavailability is only 15% due to first pass metabolism

16. completely metabolized and excreted in urine t1/2 I 7.5hr side effect are less than with metoclopramide: dry mouth loose stool headache rashes galactorrhea cardiac arrhythmias on rapid I.V injection

17. ANTIMUSCARINIC competitively inhibit action of acetylcholine at muscarinic receptor hyoscine: most effective in controlling motion sickness 0.2-0.4 mg oral, I.M brief duration of action transdermal patch 1.5mg applied behind thee pinna to be delivered over 3 days-suppresses motion sickness while producing only mild side effect

18. Neuroleptics they act by suppressing the CTZ so they antagonize vomiting produced by drug which stimulate CTZ. act by block d1 receptors in the CTZ antiemetic dose is much lower than antipsychotic doses these agents should not be administered until the cause of vomiting has been diagnosed

19. broad spectrum antiemetic, effective in: drug induced and post anesthetic nausea and vomiting disease induced vomiting chemotherapy induced morning sickness: should not be used except in hyperemesis gravidarum

20. 5-HT3 Antagonists (5-HT3) receptor antagonists block the vomiting reflex by inhibiting 5-HT3 receptors in the vomiting center, the chemoreceptor trigger zone and in the small intestine. high first pass metabolism Excreted by the liver and kidney given once or twice daily-orally or intravenously. even though 5 HT3 receptors are present in vomiting center and CTZ, the antiemetic action is restricted to emesis caused by vagal stimulation.

21. Granicetron it is 10 to 15 times more potent than ondansetron more effective in chemotherapy dose- iv 1mg Ondansetron(emeset): block 5 HT3 receptors in GIT and CTZ specially used in the chemotherapy, dose- 4mg in each ampule, 4,8 mg tablet

22. Antihistamine they act by sedating the vomiting center they are safer for long term use effective in motion sickness and vomiting due to labyrinthine disorder all antimotion drugs are more effective when taken ½-1 hr. before commencing journey once sickness has started, it is more difficult to control