Using Metoclopramide Instead Of Ondansetron And Dimenhydrinate

In our latest question and answer, the pharmacist discusses using various anti-nausea medication such as metoclopramide, ondansetron and dimenhydrinate.

Mar 28, 2018

Dr. Sam asked

Can we give metoclopramide as antiemetic instead of dimenhydrinate and ondansterone for non specified cause of vomiting? Like in cholera or for vomiting and diarrhea ..

Answer

It isn’t clear from the question, but the asker phrases it as, “Can we give metoclopramide…”, which sounds to me like the person is part of a healthcare team/staff. If this is the case, ondansetron and metoclopramide have comparable efficacy for N/V from most causes and if one is not effective, the other should be tried if not contraindicated.

Both can be given together for difficult cases where the cause has yet to be identified and addressed and the symptoms are intolerable.

Reglan (Metoclopramide)

Metoclopramide is near the top of the list of drugs for nausea and vomiting for just about any cause/etiology. It is highly effective, although not without side effects and downsides.

Metoclopramide CAN be safely used for treating nausea/vomiting of unknown cause if prescribed by a physician or other healthcare professional.

Caution and monitoring for dystonic reactions/akithesia is needed if using in patients with Parkinson’s or Restless Legs Syndrome. Metoclopramide is also preferred if the patient is pregnant (Category B in the US). In addition the drug is contraindicated in patients with pheochromocytoma, epilepsy, or bowel obstruction, and is not recommended for patients taking antipsychotic medications.

Finally, this drug will increase movement of material through the digestive tract, which may exacerbate existing diarrheal symptoms.

Zofran (Ondansetron)

Ondansetron can be a very effective anti-emetic and has a different mechanism of action that other anti-emetics. It has the most evidence for benefit in those with chemotherapy associated nausea and vomiting.

Ondansetron should be avoided in patients with a prolonged Q-T interval and can slow movement of material through the GI tract and lead to constipation. 

Dimenhydrinate

Dimenhydrinate is frequently stocked as a mild antiemetic, but this is usually only effective if the nausea stems from vertigo. If this is the case, repositioning exercises are usually the appropriate treatment, along with a less sedating medication like meclizine.

I would advise against using it otherwise…the sedating side effects are significant, and if both metoclopramide and ondansetron have failed to relieve symptoms, dimenhydrinate is not likely to help.

Additional Information

Any drug administration needs to be in the context of an ongoing clinical workup and diagnostic plan to determine why the patient is vomiting. The issues you listed are extremely different, but if a patient is suspected or confirmed to have a V. cholerae (cholera) infection, immediate medical attention is required to reduce the risk of fatal dehydration.

This is a life-threatening disease and can kill within a day. Cholera, which is rare in “first-world countries,” is characterized by production of very large volumes of liquid diarrhea that has a characteristic gray “rice water” appearance. Untreated patients may produce as much as 3-5 gallons of this liquid in a day, rapidly causing death in half of infected patients from dehydration and electrolyte losses. Mortality drops to less than 1% if treated quickly and properly. These drugs are not really used or likely to be particularly effective in cholera patients, and may cause more harm than good.

Whether the asker is a member of a healthcare team, a caregiver, or relative asking for a patient, I want to emphasize the importance of using this medication only as directed and prescribed by a physician who has examined the patient. I strongly advise against using or giving it in any other capacity. For example, if you had an old metoclopramide prescription you didn’t finish, giving someone else those pills to take for any reason is not OK. Be smart, and be safe.

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