PD-LIDs refers to the involuntary movements or so-called dyskinesias that arise as a side effect of the necessary treatment with levodopa. Dyskinesias has been a medical need ever since the introduction of levodopa in the 1970s. The reason why patients develop LIDs is likely multifactorial, but recent years of research have pointed to a specific receptor receptor for dopamine (D3) being of great importance for the occurrence of this treatment complication.

About 30% of PD patients develop LIDs
Parkinson’s disease levodopa-induced dyskinesia (PD-LIDs) involves either a part of the body such as a leg or an arm, or the entire body, causing the twisting and turning often associated with PD patients. It often arises after a period of treatment with levodopa, which is standard treatment for the core symptoms of the disease. After five years of levodopa treatment, about 30% of PD patients develop LIDs and it is increasing to about 60% after 10 years of treatment.

Only one approved treatment with limits
At present, there is no approved drug in Europe for the treatment of PD-LIDs. The drug amantadine has long been used to control PD-LIDs, even if it is not approved specifically for this problem. Amantadine does not decrease the positive effects of levodopa and can function well for certain patients. It is, however, associated with side effects (e.g. psyciatric effects), has a rather mild effect, and it has been questioned whether the drug works for periods longer than 6–12 months. Amantadine ER, a slow-acting formulation of amantadine for the treatment of PD-LIDs, was registered in the US in August 2017. When none of these treatment methods work, surgical methods such as Duodopa/Duopa or deep brain stimulation (DBS) are considered for certain patients, though only for the most severe cases owing to the side effects and high costs of the treatments.

There is a big need for therapies that can control LIDs in PD to allow greater sustainability of levodopa treatment. The only treatments available today come with serious side effects that negatively affects patients’ quality of life.