Last updated Aug. 3, 2022, by Teresa Carvalho, MS
Fact-checked by Ana de Barros, PhD
What is Mirapex for Parkinson’s disease?
How does Mirapex work?
Patients with Parkinson’s disease have a lack of dopamine, a neurotransmitter or chemical messenger that sends signals between nerve cells in the brain. This is caused by the death of nerve cells producing dopamine. One of the processes regulated by dopamine signaling is movement. The reduction of dopamine in the brain results in a progressive loss of control over movement as well as other nonmotor symptoms.
Mirapex is part of a class of drugs called “dopamine agonists.” It is a substance that mimics the effect of dopamine by binding to dopamine receptors.
The therapy has similar properties to dopamine and is thought to act as a substitute for it in the brains of Parkinson’s patients to relieve some of the motor symptoms caused by low dopamine levels.
Mirapex is frequently taken alongside levodopa, a chemical converted to dopamine by the body. Levodopa is the main treatment used for Parkinson’s once the disease has progressed. However, with extended use, many patients experience significant “off” periods — when the symptoms of the disease return before another dose of levodopa can be taken. Mirapex not only can extend the length of time levodopa is active but can also reduce daily levodopa dosage for Parkinson’s patients.
Who can take Mirapex?
Mirapex IR was approved by the U.S. Food and Drug Administration (FDA) in June 1997 and by the European Commission in March 1998 for the treatment of Parkinson’s disease.
In 2006, Mirapex was approved in the U.S and Europe for the treatment of restless legs syndrome, a neurological condition.
The ER formulation of Mirapex was approved by the FDA in February 2010 for the treatment of both early and advanced Parkinson’s. It was previously approved in Europe for the same indication in October 2009.
Who should not take Mirapex?
Because Mirapex is eliminated through the kidneys, caution should be taken when prescribing the therapy to those with kidney impairment.
Pregnant women should take Mirapex only if the potential benefit justifies the potential risk to the fetus.
Inhibition of lactation is expected since Mirapex inhibits the secretion of prolactin, the hormone responsible for the production of breast milk. Nursing mothers should carefully consider the health benefits of breastfeeding versus the potential adverse effects on the breastfed infant.
How is Mirapex administered?
Mirapex is taken orally, with or without food, either as IR or ER tablets.
- Mirapex IR tablets have a starting dose of 0.125 mg three times a day, which can be increased every five to seven days up to a maximum daily dose of 4.5 mg, given as 1.5 mg three times a day.
- ER tablets are taken once daily, with a starting dose of 0.375 mg, which can be increased gradually every five to seven days up to a maximum recommended dose of 4.5 mg per day.
Mirapex in trials for Parkinson’s disease
Trials for Mirapex IR
A range of clinical studies was conducted prior to approval, but there were three key Phase 3 trials that resulted in the therapy being approved. Two of these were conducted in early-stage Parkinson’s patients, and the third in advanced Parkinson’s patients.
The primary objective of the trials was the change in score on the four-part Unified Parkinson’s Disease Rating Scale (UPDRS) over the course of the treatment. UPDRS is a questionnaire that evaluates both motor and nonmotor symptoms related to Parkinson’s.
One trial in early-stage patients was a placebo-controlled study that enrolled 335 patients with little to no exposure to levodopa but could be on other Parkinson’s medications. The study’s goal was to assess the effect of a six-month period of Mirapex treatment compared to a placebo after a seven-week dose escalation period.
Another trial included 264 early-stage patients who were not on levodopa but could also be on other Parkinson’s medication. Patients were randomized to take one of four doses of Mirapex or a placebo.
Both studies showed a higher efficacy of Mirapex as there was a significant improvement in UPDRS scores in patients treated with this therapy.
In advanced Parkinson’s patients, a Phase 3 trial was conducted in the U.S. and Canada. The study involved 360 patients who received Mirapex for six months (following a seven-week dose escalation). Results showed a significant two-hour reduction in “off” time per day, compared to the placebo group.
Trials for Mirapex ER
The approval for Mirapex ER followed two clinical studies that showed a benefit of Mirapex ER in both early and advanced stages of Parkinson’s disease.
One study (NCT00479401) was a placebo-controlled trial in early-stage patients who had not received levodopa treatment previously. Participants received either Mirapex ER, Mirapex IR, or a placebo for a total of 33 weeks. Levodopa was allowed during the trial period if the symptoms became too severe, which occurred for 21% of patients treated with placebo but only 7% of those on Mirapex ER. A significant improvement was seen in UPDRS scores in patients treated with Mirapex ER compared to those given a placebo.
A randomized, double-blind, placebo-controlled trial also was conducted in patients with advanced disease. Patients experienced motor fluctuations on levodopa therapy and received either Mirapex ER, Mirapex IR, or a placebo for a seven-week dose titration period followed by a 26-week maintenance period. After 33 weeks, there was a significant improvement in UPDRS scores in patients treated with Mirapex ER compared to those given a placebo.
Common side effects of Mirapex
The following side effects are commonly seen in early Parkinson’s patients treated with Mirapex who are not taking levodopa:
- somnolence (sudden episodes of falling asleep)
- asthenia (loss of strength)
- peripheral edema (swelling of the hands or feet)
In advanced disease patients, who are on levodopa, common side effects include:
- dyskinesia (impaired voluntary movements)
- postural hypotension
- dry mouth
- urinary frequency
Dopamine antagonists, which are used to turn down dopamine activity, may reduce the effectiveness of Mirapex. Among those are neuroleptics, also known as antipsychotic treatments, that are used to treat many psychiatric conditions.
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