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
