Antiemetics

الناقل : elmasry | الكاتب الأصلى : H5N1 | المصدر : sayadla.com

 
Antiemetics

 
They are the drugs that is effective against vomiting and nausea

They are typically used to treat

Motion sickness

 
The side effects of opioid analgesics and chemotherapy
directed against cancer

 
And postoperative emesis


 
Main classes of antiemetics


Dopamine D2 antagonists


Metoclopramide

Domperidone

 
 
Metopimazine





 
5 HT3 receptor antagonists

Granisetron

Ondansetron

Dolasetron

Tropisetron




Antihistamines

Diphenhydramine

Dimenhydrinate

Meclizine

Cyclizine



 
(1)

 
Dopamine D2 receptor antagonists


 
(1)
Metoclopramide






 
Mode of action
is a potent dopamine D2 receptor antagonist used for its antiemetic and prokinetic properties

 
Thus it is primarily used to treat nausea and vomiting, and to facilitate gastric emptying in patients with gastric stasis

 
The anti-emetic action of metoclopramide is due to its antagonist activity at D2 receptors in the CTZ

 
At higher doses, 5-HT3 antagonist activity may also contribute to the anti-emetic effect


 
The prokinetic activity of metoclopramide is mediated by mascarinic activity, D2 receptor antagonist activity
The prokinetic itself may also contribute to the anti-emetic effect



 
Clinical uses

 
(1)
Antiemetic use

used to treat emesis associated with conditions including: emetogenic drugs, radiation sickness, malignancy, labour, and
 
 


 
considered ineffective in post-operative nausea and vomiting
and ineffective for motion sickness



 
also used by itself or in combination with paracetamol for the relief of migraine

 
as in








 
(2)
Prokinetic use

Metoclopramide
increases
peristalsis
increases tone and amplitude of gastric contractions
relaxes the
 
 

so
it is useful in the treamtent of
gastric stasis e.g. after gastric surgery
also used in
 
 



(3)
 
Other indications

 
By inhibiting the action of prolactin inhibiting hormone (i.e. dopamine), metoclopramide has sometimes been used to stimulate lactation


Contraindications
It should be used with caution in
 
 
Parkinson's disease since, as a dopamine antagonist, it may worsen symptoms

Obstruction, perforation, or hemorrhage of the stomach or small bowel

 
Not given in the first trimester of pregnancy

Metoclopramide hydrochloride is not recommended for patients under 18 years of age

Adverse effects
restlessness, drowsiness, dizziness, and headache
Extrapyramidal side effects as parkinsonism like symptoms

Dose
The usual dose is 10 milligrams 30 minutes before each meal and at bedtime


Trade names


 



 



 



 
(2)
Domperidone



 
Mode of action
Related to that of metoclopramide


 
Uses

 
(1)
Antiemetic use
used in the treatment of nausea and vomiting

It is useful in patients with
Parkinson's disease because, unlike metoclopramide , domperidone does not cross the BBB

 
(2)
Lactation
Domperidone, by acting as an anti-dopaminergic, results in increased prolactin secretion, and thus promotes lactation


 
Adverse effects
no extrapyramidal side effects as it does not cross BBB


 
Dose
The usual dose is 10 milligrams 30 minutes before each meal and at bedtime


 
Trade names

(2)
 
5 HT3 receptor antagonists



 
(1)
Granisetron

 

 
Mode of action
Granisetron is a serotonin5-HT3 receptor antagonist used to treat nausea and vomiting following chemotherapy

 
It does not have much effect on vomiting due to motion sickness


 
Clinical uses
chemotherapy induced nausea and vomiting

 
Post-operative and post-radiation nausea and vomiting


 
Adverse effects
Headache, dizziness, and constipations are the most commonly reported side effects associated with its use


 
Dose
Given intravenously about 30 minutes before beginning therapy


 
Trade names



 
(2)
Ondansetron

 



 
Mode of action

 
Clinical uses

 
Adverse effects

 
As Granisetron


 
Dose
The drug is administered 1–3 times daily, depending on the severity of nausea and/or vomiting
The normal dose for adults and children over the age of 12, is 8 mg initially, followed by a second dose of 8 mg, eight hours later. The drug is then administered once every 12 hours, usually not for more than 2-3 days


 
Trade names

 



 
(3)
Dolasetron

 


 
Mode of action

 
Clinical uses

 
Adverse effects

 
Dose

 
As Granisetron



 
(4)
Tropisetron


 
Mode of action


 
Clinical uses

 
Adverse effects

 
Dose

 
As Granisetron


 
 
Trade names