Antiemetic drugs in animals

Antiemetic drugs in animals are agents that are used to control emesis. Species like the horses, rabbits and rodents are unable to vomit.

Protracted vomiting is undesirable in dogs, cats and other species. Vomiting usually occurs secondary to another disease process. If the primary cause is treated then vomiting disappears.

Antiemetics are useful in motion sickness, uremia, liver disease, endotoxemia, canine parvovial gastroenteritis and in cancer chemotherapy.

Use of antiemetics may mask the primary disease. Prolonged vomiting leads to electrolyte and acid base imbalances and dehydration. Antiemetics may also be locally acting or centrally acting.

Classification of antiemetics

Antiemetic drugs in animals are classified in these types-

1. Anticholinergic drugs– Hyoscine, Dicyclomine
2. Antihistamine (H₁ Antagonist)- Promethazine, Diphenhydramine, Dimenhydrinate, Doxylamine, Meclozine (Meclizine), Cinnarizine
3. Neuroleptics– Chlorpromazine, Haloperidol
4. Prokinetics– Metoclopramide, Domperidone, Cisapride, Mosapride
5. 5-HT₃ Antagonists– Ondansetron, Granisetron
6. NK₁ Antagonist– Aprepitant, Fosaprepitant
7. Adjuvant antiemetics– Demulcents, Gastric antacids, dexamethasone, benzodiazepines

Hyoscine

hyoscine or scopolamine is effective for motion sickness (Suitable for short brisk journey) and have poor efficacy in vomiting of other etiology.

Dicyclomine

Dicyclomine is used for prophylaxis of motion sickness and for morning sickness (Morning sickness is very common in pregnant womens)

Meclizine

Meclizine is used in sea sickness problem. it used in small animals and have relatively long action.

Cinnarazine

Cinnarazine is a Antivertigo drug and also used for motion sickness.

Doxylamine

Doxylamine is used for prevent vomiting in early pregnancy.

Chlorpromazine

Chlorpromazine is more effective in cats then dogs.

Metoclopramide

Metoclopramide is have prominent effect on upper gastro intestinal tract, increase peristalsis. it is a Gastric hurrying agent. Metoclopramide is used in all types of emesis condition but not in motion sickness (also used in ruminal atony, gastric esophageal reflux disease)

Domperidone

Domperidone cross blood brain barrier very poorly. it absorbed orally, bioavailability is about 15% due to first pass metabolism.

Cisapride

Cisapride restore and facilitate motility throughout the Gastro intestinal tract including colon but it banned in 2011.

Ondansetron

Ondansetron used for refractory vomiting, chemotherapy and radiation induced vomition. this used successfully in puppies with parvo viral that vomit profusely despite therapy with metoclopramide.

Ondansetron have 8 to 12 hours duration of action and have minimal toxicity, it used in clinics very widely.

Granisetron

Granisetron is 10 times more potent then ondansetron

Adjuvant antiemetics

Adjuvant antiemetics such as Gastric antacids, local anesthetics also used for vomition inhibition.