Emetics and antiemetics

Emetics and antiemetics

1. PREPARED BY SALMAN HABEEB DRUGS AFFECTING GASTROINTESTINAL SYSTEM

2. COMMONLY DRUGS USED EMETICS ANTIEMETICS PROKINETICS PURGATIVES ANTACIDS ANTIDIARRHOEALS ANTIULCERS CARMINATIVES ANORECTAL PREPARATIONS

3. EMETICS EMESIS =? DRUGS THAT PRODUCE/ INDUCE VOMITING IS CALLED EMETIS

4. MECHANISM OF VOMITING WHAT IS VOMITING?  It 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 1 . vomiting center 2 .chemoreceptor trigger zone(CTZ)

5. H ow this 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 Increasing intracranial pressure by direct stimulation Stimulation of the vestibular receptors in the inner ear

6. • Intense pain fiber stimulation Direct stimulation by various chemicals, including fumes , certain drugs, and debris from cellular death CTZ is stimulated by several different processes and initiates a complex series of responses that first preparet he system for vomiting and then cause a strong backward peristalsis to rid the stomach of its contents.

7. Classification of Emetics 1.Stimulants of CTZ a.Apomorphine b.Morphine 2.Irritants of gastric mucosa a.mustard b.sodium chloride 3.Both CTZ stimulant and irritant effect a.ipecacuanha b.digitalis

8. Apomorphine It is obtained by treating morphine with HCL MECHANISM? Produce vomiting in 5-10 minutes after admn Dose - 2 to 4 mg Route - subcutaneous/IM

9. MUSTARD It is a household remedy to induce vomiting Dose- 1teaspoonful with water

10. Ipecacuanha It is obtained from the dried   rhizome and   roots  of  carapicheae ipecacuanha from which it derives its name . Commonly available as syrup Dose- 15 to 20ml Induce vomiting witin 15 minutes

11. Antiemetics Drugs that prevent vomiting

12. CLASSIFICATION 1.Prokinetics a.metochlorpramide b.domperidone 2.Antimuscarinics a.hyocine b.meclozine 3.Antihistamines a.cyclizine b.promethazine ( phenergan ) 4 .Neuroleptics a.chlorpromazine b.prochlorpromazine 5 . 5-HT3 antagonists a.ondancetron b.granicetron

13. P rokinetics These drugs which promote gastrointestinal motility and quicken gastric emptying Metoclorpramide (REGLAN) It has both central and peripheral effects Central- blocks the dopeminergic receptors peripheral- increased gastric emptying dose- 5- 10 mg

14. Metochlopramide ( reglan ) Dose- 5-10 mg Indications post-operative vomiting, vomiting during induction of anesthesia Side effects: restlessness, drowsiness , dizziness , and or dystonic reactions.

15. Domeperidone Action - Block the dopaminergic receptors in the upper GIT Dose- 10mg,30mg tablets 1mg/ml syrup Side effects: Headache, dizziness, dry mouth, nervousness, flushing, or irritability

16. Antimuscarinics Action- Competitively inhibits action of acetylcholine at muscarinic receptors Hyoscine –very effective in controlling motion sickness Dose -0.4-0.6 mg po 30 min before journey It is a labrynthine sedative

17. Neuroleptics Action- they act by suppressing the CTZ so they antagonize vomiting produced by drugs which stiimulate CTZ Eg ; chlorpromazine dose; PO: 10-25 mg q4-6hr IV/IM : 25-50 mg q4-6hr

18. 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

19. Ondansetron ( Emeset ) Blocks 5HT3 receptors in git and CTZ Specially used In chemotherapy,post op vomiting other drug induced vomiting Dose- 4mg in each ampule 4,8 mg tab

20. Side effects : Headache , constipation, and dizziness are the most commonly reported side effects associated with its use

21. G ranisetron It is 10 to 15 times more potent than ondansetron More effective in chemotherapy Dose – IV 1mg

22. Antihistamines They act by sedating the vomiting centre They are safer for long term use Effective in motion sickness and vomiting due to labrynthine disoders eg . Cyclizine meclozine dose- 50mg/ml inj 50mg tab

23. Nursing Considerations for Patients Receiving an Antiemetic Agent Assess for possible contraindications or cautions history of allergy to antiemetic to avoid potential hypersensitivity reactions; impaired renal or hepatic function ■ Assess the patient’s neurological status, including level of orientation, affect, and reflexes ,

24. ■ Examine the abdomen, including the liver, and auscultate bowel sounds ■ Assess complaints of nausea and evaluate emesis ; note color , amount, and frequency of vomiting episodes

25. Instruct the client to avoid over-the-counter preparations. Instruct the client not to consume alcohol while taking antiemetics . Advise pregnant women to avoid antiemetics during the first trimester.