Buspirone Treatment of Iatrogenic Dyskinesias in Advanced Parkinson' Disease. Multicenter, International, Placebo-controlled, Randomised, Double Blind Trial

Parkinson's disease (PD) is one of the most common neurodegenerative diseases, with a higher prevalence in the elderly. Levodopa induced dyskinesias (LID) are a major motor complications that impair quality of life for patients with PD. The mechanisms of these dyskinesias remain unclear, but several hypotheses have been put forward: non continuous, pulsatile stimulation of dopaminergic receptors, or alterations of other neurotransmitters within the motor striatum such as glutamate and serotonin.

Few strategies are now available to treat severe LID:

• Medications: reduction of dopaminergic treatment, addition of amantadine,
• Functional neurosurgery. The purpose of this study is to investigate the efficacy of buspirone in PD patients suffering from dyskinesias. The role of serotonin in the occurrence of LID was recently demonstrated in transplant PD patients and a test double-blind, single dose was achieved. Following administration of 10 mg oral buspirone, a 5HT1A agonist, LID were clearly improved. A antidyskinetic effect of buspirone had already been reported in 1991 and 1994, but identification of buspirone as a serotonin receptor agonist has been reported more recently.

This trial is aimed at (1) validate the serotoninergic hypothesis of hyperkinetic levodopa induced dyskinesias (LID) in Pakinson's disease patients, (2) evaluate, in a phase 3 trial, the motor efficacy of buspirone to improve LID vs placebo, (3) look at a possible dose/effect relationship and (4) check the hypothesis of a better therapeutic ratio using the association of buspirone and amantadine instead than a single drug.