It is available as an immediate release formulation (Requip) or as an extended release formulation (Requip XL).
How Requip works
Parkinson’s disease is a neurodegenerative disorder in which nerve cells in the brain that produce dopamine — a chemical messenger that sends signals between brain cells — slowly die. Dopamine is essential to sending messages to coordinate movement, and decreasing levels result in a progressive loss of control over movement and various other symptoms.
Requip is a dopamine agonist. It is a substance that has similar properties to dopamine and can mimic some of the functions of dopamine in the brain. Therefore, it can act as a substitute for the decreasing amounts of dopamine in the brains of Parkinson’s patients.
It is often prescribed alongside levodopa, a chemical that is converted to dopamine in the brain, to extend the period that levodopa is active and reduce motor symptoms in the patient.
Requip in clinical trials
The original immediate-release oral tablets were approved by the U.S. Food and Drug Administration (FDA) in 1997. This approval was based on three key clinical trials that demonstrated the safety and effectiveness of the tablets.
The three trials were randomized, double-blinded and placebo controlled. The effect is compared to the placebo was assessed using the Unified Parkinson’s Disease Rating Scale (UPDRS) to check for changes in how the motor and non-motor symptoms of Parkinson’s disease affected daily activities, the overall motor ability of the patient, and whether the medication is safe. Phase 1 and 2 trials were carried out in early-stage Parkinson’s disease patients who had not received levodopa, and a Phase 3 trial enrolled patients who received Requip with levodopa.
The Phase 1 trial assessed the most effective dose and showed a significant difference in improvement (classed as a 30 percent decrease in the UPDRS motor score) compared to the placebo.
A Phase 2 trial 2 assessed Requip dosage and how early-stage Parkinson’s disease patients responded to Requip over a six-month period. The UPDRS motor score of patients treated with a placebo or with Requip was assessed at the start and end of the study. The Requip treatment group showed an improvement in UPDRS score (a 22 percent decrease), whereas the placebo showed a worsening of symptoms (a 4 percent increase in the UPDRS score). This difference was significant.
The Phase 3 clinical assessed how Requip interacted with levodopa in advanced-stage Parkinson’s disease patients. By the end of a six-month period, patients treated with Requip and levodopa experienced 90 minutes less “off” time (between doses of levodopa when symptoms re-emerge) compared to the placebo, corresponding to a 0.9 hours reduction.
Approval of Requip XL, in 2008, was supported by two additional clinical trials. Trial 4 was carried out on advanced Parkinson’s patients receiving levodopa and Trial 5 assessed the effectiveness in early-stage Parkinson’s disease patients prior to levodopa treatment.
Trial 4 demonstrated that it could reduce the “off” time between levodopa doses by 2.1 hours, compared to a reduction of 0.4 hours seen in the placebo group.
Trial 5 assessed whether it had any benefit over the immediate release tablets in early-stage Parkinson’s disease patients. There was no significant difference seen between the two formulations.
The most common side effects experienced by patients are fainting, dizziness, drowsiness, dyskinesia (involuntary movements), fatigue, nausea, and viral infections.
Both Requip and Requip XL are available as a oral tablet.
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