Reglan
Meaning of Reglan: Blocking dopamine explains both what this drug does for nausea and the movement problems that limit how long it is given.
Definition of Reglan
Reglan is a brand name for metoclopramide, a medicine that speeds movement through the stomach and the first part of the small intestine while also blocking nausea signals in the brain. It is given for nausea and vomiting and for delayed stomach emptying, by mouth or by injection, and it is one of the older drugs still in regular use.
How does it work?
Metoclopramide blocks dopamine receptors, and dopamine turns out to be doing two separate jobs that both matter here. In the wall of the stomach, dopamine damps down muscular activity, so blocking it strengthens and coordinates contractions and relaxes the outlet, pushing contents onward into the intestine. In a small region of the brainstem that monitors the blood for toxins and triggers vomiting, blocking dopamine interrupts the nausea signal directly. At higher doses the drug also blocks a serotonin receptor involved in vomiting, which adds to the effect.
What is it used for?
The main use is gastroparesis, in which the stomach empties too slowly and produces nausea, bloating and a feeling of fullness after only a few mouthfuls. It is also used for nausea and vomiting from other causes, including some chemotherapy regimens and migraine, where slowed stomach emptying also holds up the absorption of other tablets. In hospital it is used to help advance a feeding tube past the stomach and to empty the stomach before certain procedures.
Why is the length of treatment limited?
| Movement effect | Timing | Course |
|---|---|---|
| Acute muscle spasm of the neck, jaw or eyes | Hours to days after starting, more often in younger people | Settles once the drug is stopped and can be treated |
| Restlessness with an urge to keep moving | Early in treatment | Resolves after the drug is withdrawn |
| Slowness and tremor resembling Parkinson disease | Weeks to months | Usually improves after stopping |
| Tardive dyskinesia, involuntary movements of face and tongue | Months of continued use | May persist after the drug is stopped |
The last of these is the reason the label carries its strongest warning and why courses are kept short. The risk grows with the total amount taken over time and with age, which is a different pattern from a side effect that depends on the size of a single dose.
Also known as
Used in a sentence
Reglan was administered to help control the patient's nausea related to delayed stomach emptying.
Good to know
Reglan acts on dopamine receptors, which separates its side effect profile from anti-nausea drugs working through other pathways and explains why the risk of movement problems grows with the total amount taken over time.