A dopamine agonist is an interesting medication that is most useful in early treatment of Parkinson’s disease and in conditions like restless legs syndrome (RLS). Its mechanism of action is to work on dopamine receptors so that they are stimulated. This is different than adding dopamine to the body, which would stimulate the receptors, and it’s also distinct from preventing the body from taking up (reuptake) free dopamine so there is more in use. Instead, it’s something like a substitute for dopamine that can fool dopamine receptors into working, even when the body lacks a good supply of this neurotransmitter.
One of the reasons why dopamine agonist drugs can be of great use in treating diseases like Parkinson’s is due to the diminishing presence of dopamine in this condition. A steadily decreasing supply of this neurotransmitter translates to many of the developing symptoms of the disease. While in late stages, giving medications like straight dopamine or L-dopa might be part of treatment, in early stages, a dopamine agonist may be of most use in preventing symptoms from progressing. In conditions like RLS, a dopamine agonist may not only slow disease progression, but could result in complete cessation of symptoms, while the drug remains in use.
There are a number of dopamine agonist medications that are in use for different conditions. For RLS, drugs like pramiprexole (Mirapex®) and ropinirole (Requip®) are common choices. With Parkinson’s disease cabergoline or bromocriptine might be the best choices. Other medications with dopamine agonist properties exist and might be chosen instead, depending on a patient’s individual circumstances. Medications for RLS may be useful in calming restless sensations and for Parkinson’s may be able to reduce involuntary movements.
Such drugs do have side effects including possibility of increasing involuntary movements, or causing severe mood disturbance, especially in people with mood disorders. Alternately, some people taking these medications may feel overly happy, leading to poor judgment about spending or consuming alcohol. Other side effects reported include tiredness, dizziness, light-headedness, faint feelings, trouble sleeping, changes in weight, hallucinations, and low blood pressure. Any incidence of side effects varies by person, dose adjustment sometimes rids the person of side effects, and switching to a different dopamine agonist may alleviate issues.
One of the more profound reactions to these medications is change in behavior that could include development of compulsive or addictive behaviors like gambling, drug use or sexual addiction. In the first decade of the 2000s, a number of lawsuits have arisen against drug companies for not warning people of these serious effects, which were certainly known earlier. While these drugs may be viewed as important, all people contemplating taking a dopamine agonist should make themselves fully aware of potential side effects. This allows folks to report any side effects early and get medical advice on other treatments that might be more appropriate.