Anti-Emetics Flashcards
Mention some aetiologies of vomiting
Alcohol intoxication
Radiation exposure
Medications
GI tract disorders
Pregnancy
Myocardial infarction
Mention some drugs that cause vomiting
Metformin
Anti-parkinsonians, e.g., bromcryptine, L-DOPA
Anti-convulsants, e.g., phenytoin, carbamazepine
Anti-hypertensives
Theophylline
Anesthetic agents
Oral contraceptives
Cancer chemotherapy
Parts of the vomiting pathway and their receptors
CTZ - D2 R and 5-HT R, Opioid receptors
Vomiting centre - AChM, 5-HT, H1
Vestibular nuclei - AChM, H1
Pharynx and GIT - 5-HT
Examples of emetic drugs
Ipecacuanha (emetine and cephaeline), Apomorphine
Pharmacological action of apomorphine
It is a dopamine agonist acting on the CTZ
Pharmacological action of apomorphine
It is a dopamine agonist acting on the CTZ
Pharmacological action of ipecacuanha
Gastric irritation
Classes of anti-emetics
Serotonin 5 HT3 Antagonists
Dopamine D2 Antagonist
Anticholinergics
H1 Antihistaminics
Cannabinoids
Classes of anti-emetics
Serotonin 5 HT3 Antagonists
Dopamine D2 Antagonist
Anticholinergics
H1 Antihistaminics
Cannabinoids
Pharmacological action of 5 HT3 Antagonists
Primarily antagonizes serotonin release by the enterochromaffin cells of the small intestine, which is usually released in response to chemotherapeutic agents and stimulates vagal afferents (via 5HT3 receptors) to initiate the vomiting reflex. It may also antagonize it in the CTZ and vomiting centre.
RODA for Serotonin 5-HT3 Antagonist
Oral, IV
What are the 5HT3 antagonists?
Ondansetron
Granisetron
Dolasetron
What are the dopamine D2 antagonists?
Metoclopramide
Domperidone
What is the MOA of dopamine D2 antagonists?
They antagonise D2 receptors in CTZ, reducing NT release
Which D2 antagonist causes Parkinsonism-like effects? Why?
Metoclopromide; it crosses the BBB
Other classes of drugs displaying D2 antagonism
Phenothiazines & Butyrophenones
Examples of Phenothiazines
Prochlorperazine
Promethazine (H1 antagonist)
Chlorpromazine
Pharmacological actions of Phenothiazines
They are are antipsychotics with potent antiemetic property due to D2 antagonism
Droperidol is a ___ with a side effect that includes ___
Butyrophenone, prolonged QR interval (bradycardia)
Examples of antihistamines
Meclizine
Cyclizine
Dimenhydrinate
Diphenydramine
Promethazine
What is the rationale for antihistamine use in motion sickness?
H1 receptors in the vestibular nuclei
Examples of cannabinoids
Dronabinol and Nabilone
Therapeutic use of cannabinoids
Treats vomiting caused by cytotoxic anticancer drugs
Adverse effects of cannabinoids
Drowsiness, dizziness, dry mouth mood changes, hallucinations
Example of anti-emetic steroid
Dexamethasone
