Restless Legs Syndrome – approved indication for Adartrel and Sifrol
Adartrel and Sifrol were recently approved for use in Restless Legs Syndrome.
Efficacy has mainly been evaluated by means of the International Restless Legs Society (ILRS) scale or by Periodic Leg Movements (PLM) during sleep (PLMS) or wakefulness (PLMW). The subjective but thoroughly validated IRLS-scale is probably a better measure of the patients’ benefit from treatment than the objective measure of PLM, PLMS and PLMW. Consensus regarding which parameter to use in clinical trials is needed. No studies compare the two substances directly.
In the Adartrel trials a limit on 6 point on the IRLS scale was used when determining the population size. The difference between placebo and Adartrel treatment was 2.5-3.7 points. The difference reached 4 points in a selected group of patients. A difference of 4.3 points on the IRLS-scale was found between placebo and Sifrol treatment.
There are several possible reasons for the disappointing difference between placebo and active treatment. In one study, a correlation between the severity of the disorder and the efficacy of treatment was shown. The authors therefore stated that the small difference was caused by the included patients not being affected enough. The small difference could, however, also be a consequence of the actual effect of the products.
When measuring PLM, Adartrel resulted in a 75 % reduction in the number of nightly involuntary leg movements per hour compared to a 7 % reduction with placebo. Treatment with Sifrol resulted in a 74-98 % reduction compared to a 3-12 % reduction with placebo.
Medical treatment is only to be used in patients with daily symptoms, when lifestyle changes have had no effect.
Institute for Rational Pharmacotherapy, 5 September 2006