I am often intrigued to connect with clinicians who have various opinions on medications.  In particular to GI motility agents, we often discuss the safety profile of domperidone vs. metoclopramide.  They are both dopamine antagonists; one main difference is that domperidone works peripherally whereas metoclopramide can cross blood brain barriers and exert some central system effects.  The other difference is that domperidone is not commercially available in United States but only via a special access mechanism. As such, there may be more documented clinical evidence and experience with metoclopramide than with domperidone.

Nonetheless,  it isn’t uncommon that some physicians may be terrified to prescribe domperidone because of the concerns with QT prolongation and possible risk of sudden cardiac deaths.  Health Canada did release an alert few years ago, highlighting such possibilities. 

As for metoclopramide, there is a preception that it is a safer agent. But while the risk for QT prolongation may not be as serious (as noted in crediblemed.org), there are other serious side effects that should be noted.  Because metoclopramide is a dopamine antagonist that can cross the blood brain barrier, it may exhibit side effects  similar to other dopamine antagonists (e.g. antipsychotics) including abnormal movement disorders and extrapyramidal side effects. Health Canada also has alerted to such warnings few years ago.   These side effects may not be reversible, even if the medication is discontinued.

So in my opinion, I think metoclopramide is just as “unsafe”, when compared to domperidone.

When it comes to deciding on which agent to try or use in clinical context, here are some of my thoughts:

Indication – GI motility agents have several indications – from gastroparesis to prevention of nausea and vomiting associated with anti-Parkinson’s agent.  I think it is important to assess if an agent has been tried and consider alternate agents as necessary.  My first choice is domperidone and titrate the dose slowly. But if domperidone has been tried and not effective, then it would make sense to consider metoclopramide.   If a motility agent is needed for symptom management in palliative care, then I would prefer metoclopramide, with the option to give the injectable option when the patient develops dysphagia.

Dose:  The cumulative daily dose matters, especially in the context of assessing QT prolongation risk. Can we consider a lower dose? What about doing a baseline ECG to measure the QTc before treatment.

Duration of Use:  The intent of treatment duration also affect my choice or selection. If a patient’s nausea is transient and just needs some temporary relief, I would be more comfortable to recommend metoclopramide, given the risk with extrapyramidal side effect tends to be related to long term use. However if a patient may require indefinite treatment with a GI motility agent, then I would avoid metoclopramide if possible.

These are just some of my random thoughts based on my experience with these two agents. What are your thoughts with domperidone vs. metoclopramide? Which one is worse? Which one is better?

Thank you for reading my post.