Anti- Emetic

 Anti- Emetic

VOMITING (EMESIS);

It is protective reflex mechanism for eliminating irritant or harmful  substance from upper GIT. 

Control of Vomiting:

Vomiting is controlled by vomiting center located in the reticular formation of medulla, that coordinates act of emesis on receiving stimuli from

1. Chemoreceptors trigger zone ( CTZ)

2. Vestibular system

3. Periphery e.g in distension or irritation of gut, Myocardial infarction, Biliary or renal calculus

4. Corticle centers

CAUSES OF VOMITING

1.       Pregnancy

2.       Motion sickness

3.       GI obstruction

4.       Peptic ulcer

5.       Drug toxicity

6.       Myocardial infarction

7.       Renal failure

8.       Hepatitis

DRUG CLASSIFICATION

CENTRAL ANTI-EMETICS

1. Dopamine D2-Receptors Antagonists: Droperidol, Haloperidol

2. Sedative–Hypnotics: Barbiturates, Benzodiazepines

3. Neurokinin  Receptors Antagonists: Aprepitant

4. Cannabinoids: Dronabinol, Nabilone

CENTRAL & PERIPHERAL ANTI-EMETICS

1. D2- Receptors Antagonists

a) Substituted Benzamides: Metoclopramide, Trimethobenzamide

b) Phenothiazines: Chorpromazine, Prochlorperaine, Promethazine

2. Serotonine 5HT3- Receptors Antagonists: ondannsteron, Granisteron. Dolasterone

3. Antimuscarinics: Scopolamine, Atropine

4. H2- Receptors Antagonists: Cyclizine, Cinnarizine, Meclizine, Diphenhydramine

PERIPHERAL ANTI- EMETICS

1. Demulcents: Gum acacia, Gum tragacanth

2. Adsorbents: Aluminium hydroxide, kaolin

3. Gastric Mucosal anesthetics: chloretone, dilute hydrocyanic acid

METACLOPRAMIDE

MECHANISM OF ACTION

1. Central

Block dopamine D2- receptors in CTZ

2. Peripheral

Enhances action of ac etylcholine at muscarinic nerveending in gut- this causes

a) Inc. tone of lower esophageal sphinter

b) Relaxation of pyloric antrum & duodenal cap.

c) Inc. peristalsis & emptying of upper gut

CLINICAL USES

1. Nausea and vomiting associated with

a) GI disorders

b) Post surgical conditions

c) Cytotoxic drugs

d) Radiotherapy

2. To empty stomach

a) Before emergency anesthesia

b) In labor

c) In diabetic gastroparesis

d) After vagotomy

e) In gastroesophageal reflex

ADVERSE EFFECTS

1. CNS: Restlessness, facial spasm, trimus, 

2. GIT: Diarrhea

3. Endocrine: Gynecomastia, laction

Precautions

1. Pregnancy & lactation

2. Renal or hepatic impairment

CONTRAINDICATIONS

1. Recent gastrointestinal surgery

2. Prolactin- depedent breast carcinoma

3. Pheochromocytoma

Dosage

10mg TDS orally IM or IV

DRUG TREATMENT OF SPECIFIC VOMITING

A. Motion sickness

1. Cinnarizine

2. Cyclizine 

3. Dimenhydrinate

4. Scopolamine

5. Promethazine

B. Vomiting due to cytotoxic drugs

1. Dexamethasone

2. Lorazepam

3. Metachlopromide

4. Ondansetron

C. Vomiting in pregnancy

1. Promethazine

2. Thiethylperazine

3. Vit. B6

4. Vit. B6 plus meclizine

D. Vertigo 

1. Scopolamine 

2. Phenothiazines

3. Cyclizine 

4. Betahistine 

5. Cinnarizine

GENERIC & TRADE NAMES

A. D2- Receptors Antagonists

• Haloperidol: Haldol, Serenace

• Metachlorpramide: Digestine, Fimet, Gastrolon, Maxolon, Metoclon, Metomide, Plasil, Regelan

• Domperidone: Costi, Motilium, Pelton,Peridone

• Chlorpomazine: Largactil, sedectil

• Prochlorperazine: Dometil, Stabil, Stemetil

• Promethazine: Avomine, Phenergan, phenerzine

• Thiethylperazine: Torecan

• Acepromazine: Acozine

B. 5-HT3-Receptors Antagonists

• Oandansetron: Ondison, Steron, Zofran

• Tropestron: Navoban

C. H1-Receptors Antagonists

• Cyclizine: Marzine, Migril

• Cinnarizine: Cerebrin, Stugeron

• Dimenhydrinate: Devinate, Dimenic, Gravinate

• Meclizine: Navidoxine, Sevidoxine

• Promethazine: miprozine, o-zine, phenegran, promazine, semozine