Anti-emetic drugs, classification, mnemonic || ONI
Anti-emetic drugs, classification, mnemonic || ONI

What are the antiemetic drugs

Antiemetic are the drugs use to prevent vomiting and suppress the vomiting. 

Vomiting occur due to stimulation in vomiting center. It is also related to other etiology like irritation in gastrointestinal tract. 

    Ondansetron which is an example of antiemetic drugs is considered as a best antiemetic drugs because it is class of 5HT3 which blocks the serotonin. 

    Antiemetic drugs are safe in adults and also child if you take it according to the instructions of your doctor and it not cause any side effect in your body. 

    Antiemetic drugs are found both in tablets and injection Ondansetron, promethazine, dicyclomine etc. 


    Classification of antiemetic drugs

    (1) Anti-cholinergic drugs

    • Hyoscine
    • Dicyclomine
    • Hydrobromide

    (2) Antihistamine drugs 

    • Promethazine
    • Meclizine
    • Cyclizine

    (3) Pro-kinetic drugs

    • Metoclopramide
    • Domperidone

    (4) Neuroleptic drugs

    • Haloperidol
    • Prochlorperazine

    (5) 5HT3 Antagonist

    • Ondansetron
    • Granisetron

    (6) Other

    • Benzodiazepine 

    (1) Anti-cholinergic drugs :-

    Anti-cholinergic drugs are the class of drug of antiemetic drugs are inhibit the conduction of emetic sensation bind with neurotransmitter acetylcholine and inhibit the muscarinic receptor. 

    muscarinic receptor are found on the nerve ending of smooth muscles and secretory cell. 

    (A) Dicyclomine :- It is orderless, water soluble and Cristal form drugs which are used as a antiemetic drugs and also known as anti-cholinergic or antispasmodic drugs. 

    DOSE :- 20 mg oral and 10 to 20 mg IM

    (B) Hyoscine :- Hyoscine is most effective antiemetic drugs of motion sickness. Transdermal patch applied behind pinna which delivered Hyoscine for 3 days. It blocking the conduction of drugs impulse is non effective in vomiting of other etiology. 

    (2) Antihistamine drugs :-

    Antihistamine drugs are the drugs which prevent the histamine. These type of antiemetic drugs are used for symptomatic treatment of allergic disorder. 

    The antihistamine have been divided into H1 and H2 blocker. It is receptor act on GIT. 

    Promethazine :- It is a class of antihistamine drugs which is used to treat vomiting. It is water soluble drug. This drugs not prevent from release of histamine but act by blocking the H1 and H2 receptor in gastrointestinal tract. 

    DOSE :- 10 to 25 mg oral, IM

    (3) Pro-kinetic drugs :-

    Pro-kinetic drugs is a type of antiemetic drugs which enhance gastrointestinal mortality by increase the frequency and decrease the rhythm. 

    (4) Neuroleptic :-

    These type of antiemetic drugs are suppress the nerve impulse of the CTZ vomiting center. 

    (5) 5HT3 Antagonist :-

    Ondansetron :- Ondansetron block the action to of CTZ and prevent the nausea and vomiting. 

    After the use of Ondansetron headache, dry mouth, dizziness are commonly seen. 

    Ondansetron are effective in nausea and vomiting if it is related to use of any medication.


    Mnemonic for remembering antiemetic drugs

    The best and easy mnemonic for antiemetic drugs is given by usmlematerials website which helps you to easily remember the classification of antiemetic drugs if you want to this mnemonic then click here


    Mechanism of action of antiemetic drugs

    (1) Mechanism of action of anticholinergic drugs


    Administer anticholinergic drugs like dicyclomine
    ⇓
    Bind with neurotransmitter acetylcholine
    ⇓
    Blocks transmission of nerve impulses
    ⇓
    Inhibit conduction of emetic sensation
    ⇓
    Stop vomiting

    (2) Mechanism of action of antihistamine drugs


    If vomiting occur due to the allergic condition administer drug like promethazine
    ⇓
    Block H1 and H2 receptor (present on nerve endings) 
    ⇓
    Prevent from bounding of histamine 
    ⇓
    Inhibit histamine action in CTZ vomiting center
    ⇓
    Stop vomiting

    (3) Mechanism of action of pro-kinetic drugs


    If vomiting occur due to gastrointestinal tract irritation administer drug like domperidone
    ⇓
    Increase frequency and decrease rhythm
    ⇓
    Enhance GIT mortality
    ⇓
    Stomach empty fastly
    ⇓
    Stop vomiting

    (4) Mechanism of action of neuroleptic drugs


    Administer drug like prochlorperazine
    ⇓
    Block the action of neurotransmitter like acetylcholine 
    ⇓
    Suppress the nerve impulses to the CTZ vomiting center
    ⇓
    Stop vomiting

    (5) Mechanism of action of 5HT3 Antagonist

    If vomiting occur due to chemotherapy and radiation therapy Administer drug like ondansetron

     ⇓

    Block the serotonin 

    ⇓

    Inhibit nerve impulses to the CTZ vomiting center

    ⇓

    Stop vomiting

     


    Uses of antiemetic drugs

    (1) Uses of anticholinergic drugs

    • Motion sickness
    • Morning sickness
    • Dysmenorrhoea
    • Irritable bowl disease

    (2) Uses of antihistamine drugs

    • Allergic conditions
    • Motion sickness

    (3) Uses of pro-kinetic drugs

    • Vomiting due to chemotherapy and radiation
    • Vomiting due to food poisoning
    • Post-operative-vomiting
    • Nausea

    (4) Uses of neuroleptic drugs

    • Vomiting
    • Nausea
    • Migrain
    • Schizophrenia
    • Psychotic problem

    (5) Uses of 5HT3 Antagonist

    • Nausea and vomiting due to chemotherapy


    Side effect of antiemetic drugs

    (1) Side effect of anticholinergic drugs

    • Dry mouth
    • Headache
    • Loss of sleep
    • Anxiety
    • Tachycardia
    • Heart burn

    (2) Side effect of antihistamine drugs

    • Tachycardia
    • Dry mouth
    • Hypotension

    (3) Side effect of pro-kinetic drugs

    • Diarrhoea
    • Abdominal cramps
    • Blurred vision
    • Upset stomach
    • Drowsiness

    (4) Side effect of neuroleptic drugs

    • Constipation
    • Dry mouth
    • Sedation
    • Sexual problem due to hormonal changes
    • Akathisia

    (5) Side effect of 5HT3 Antagonist

    • Diarrhoea
    • Headache
    • Dizziness
    • Constipation

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