Antiemetics

Antiemetics
are the Drugs which prevents or control the Vomiting/Nausea.

Classification

5HT3 Antagonists – Ondansetron, Granisetron, Dolasetron.

Prokinetics / Dopamine Antagonists – Domperidone, Olanzapine, Metoclopramide

Antihistamines – Cyclizine, Diphenhydramine,
Meclozine, Promethazine, Hydroxyzine.

Anticholinergics – HydroxyzineHyoscine &
Dicyclomine.

Mechanism of action

5HT3 Antagonists They block serotonin receptors in
CNS and Gastrointestinal tract so they can be used to treat post-operative
cytotoxic (Chemotherapy) drugs nausea/ vomiting.

Prokinetics (Dopamine Antagonists): They block The Dopamin neurotransmitter
also they promote gastrointestinal motility & quicken gastric emptying.

Antihistamines: They block the histamine
neurotransmitter and they act by an effect on vomiting center and by producing
sedative effect.

Anticholinergics: An Anticholinergic agent block the neurotransmitter
Acetyl choline in central and peripheral nervous system.

Durgs and
their Dosage

1 Hyoscine –
200-600mg (SC)

2 Diclomine –
40mg 6hourly

3 Cyclizine
– 50mg 4-6 hour

4 Meclizine
– 25mg/day

5
Metoclopramide – 10mg

6
Domperidone – 10-20 mg 4-6hours

7
Ondansetron – 8-16mg

Indications / Uses

5HT3
antagonists are used in management of nausea vomiting associated with
chemotherapy.

Antihistamine
such as diphen hydramine is used for motion sickness and morning sickness.

Metoclopramide
is used for gastric emptying in patient’s receiving tube feeding.

Anticholinergic
such as hyoscine, Dicyclomine are useful in travel sickness.

Contraindication / Precautions

Diphenhydramine
is contraindicated in hypertensive patients.

Metoclopramide
is contraindicated in suspected gastrointestinal problem.

Use
cautiously and reduced dose in renal impairment conditions.

Adverse effects

Hypotension.

Constipation.

Dryness of
mouth.

Blurred
vision.

Pain in IM
injection site.

Drowsiness.

Rectal
irritation.

Photo
sensitivity reaction.

Drug interactions

Use
antihistamine, other CNS depressants including opioids and sedative -hypnotic drugs
causes additive CNS depression.

Metoclopramide
affects GI motility and alter GI absorption of other drugs such as salicylates,
levodopa, diazepam, lithium, and tetracycline.

Antiemetics Drugs Notes PDF