Reglan - Side Effects and Withdrawal Symptoms
Reglan, one of the trade names for a drug the medical term for which is metoclopramide, is classified as a dopamine antagonist. In order to understand how the side effects of this drug, it is helpful to know something about how the brain and nervous system work together in order to control bodily functions and the role of dopamine.
The Body's Internet
Think of your brain as a server and your nervous system as the Internet. In this case, your "Internet terminals" are the individual cells. The brain issues instructions to these cells via your nervous system. Just as sending data over the Internet requires electrical energy however, so too do brain signals require something to convey its instructions along the neural pathways. The transmitter in this case is a nerochemical called dopamine.
In order to receive these instructions, however it is necessary for them to be translated into a form that the cells can understand. Just as your personal computer has a modem in order to translate electrical data into information your browser can read, so too do your cells have dopamine receptors, which receive and translate instructions from the brain.
There are several different kinds of dopamine and dopamine receptors, each of which deal with specific bodily and/or neural functions. Drugs that are dopamine antagonists block these signals for specific dopamine receptors.
Anti-Psychotics and Others
Dopamine antagonists were originally developed in the 1950s and '60s in order to treat psychiatric patients. These drugs targeted a specific dopamine receptor known as D2, which is responsible for the control of certain muscle operations and neural feedback mechanisms.
Metoclopramide was initially developed for this purpose, but was found to be less effective than many other antipsychotic drugs then in use. However, it was effective in controlling certain gastrointestinal disorders; by blocking dopamine receptors of the digestive system, a number of different symptoms – such as heartburn, acid reflux, gastroparesis (partial or complete paralysis of the stomach) could effectively be controlled.
Problems Become Apparent
Metoclopramide became popular in the late 1990s after its predecessor, Cisapride, was found to cause serious side effects. However, the former was found to have its own dangers. A study published in 2004 found that like many other dopamine antagonists, metoclopramide could cause a movement disorder known as tardive dyskinesia, which is characterized by uncontrollable movements in the muscles of the face, jaw and extremities. These symptoms were more likely to occur in older female patients who had taken the drug for an extended period of time, but could appear in anyone. This ultimately led to action by the Food and Drug Administration, requiring a "black box" warning on all packages of Reglan.
Other Side Effects
Although tardive dyskinesia is one of the more visible side effects of Reglan, there are several others, some of which are life-threatening and can result from withdrawal once the patient is taken off the medication after an extended period of time.
Nor is tardive dyskinesia the only movement disorder that may result from Reglan use: symptoms associated with Parkinson's Disease, which is in many ways the opposite of tardive dyskinesia (instead of uncontrollable movements, the patient may have difficulties in initiating movement) can occur as well. Occasionally, use of Reglan has been known to trigger seizures or convulsions. Patients with epilepsy may be especially susceptible.
Some patients have reported undefined feelings of anxiety, restlessness, agitation and sleep difficulties. In extreme cases, patients have been known to become suicidal.
More obvious side effects can include dryness of the mouth and ironically, gastrointestinal disorders that include constipation as well as diarrhea. Some patients experience loss of bladder control (incontinence); Reglan can also act as a diuretic, increasing the production of urine. Rarely, patients may suffer from fever, sore throat and/or chills as well as symptoms associated with liver disease, including nausea and vomiting and dark urine as well as jaundice (yellowing of the eyes and skin).
Dizziness and changes in vision can occur in a number of patients.
Sexual Dysfunction and Heart Problems?
Excessive breast tenderness and menstrual changes have been noticed in certain female patients: males may experience gynecomastia (development of male "breasts") and impotence.
Extended Reglan use is also associated with a potentially life-threatening heart condition called tachycardia, or abnormally fast heart rate; arrhythmia, or uneven heart rate is not unknown. Reglan can aggravate hypertension or cause hypotension (low blood pressure) as well.
Neuroleptic Malignant Syndrome
Reglan patients suffering from fever, muscular stiffness, movement difficulties, delirium, or movement difficulties should call a physician right away, as these may be symptoms of neuroleptic malignant syndrome, a condition associated with dysfunction of the D2 dopamine receptor. It is potentially life-threatening if not treated right away.
© 2010 TardiveDyskinesia.com Last Modified Monday, July 27th, 2009
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