Rapid treatment of "wearing off" in Parkinson's disease.

Patients with advanced Parkinson's disease (PD) may develop a variety of motor complications associated with levodopa therapy. Motor fluctuations, such as early morning akinesia and "wearing-off," may respond to individualized medical management with titrated combinations of levodopa, dopamine agonists, COMT inhibitors and amantadine. Often with disease progression, dyskinesias and unpredictable, rapid "off" periods will also emerge. These motor complications are less amenable to traditional anti-parkinson therapy manipulation. This manuscript reviews approaches for "rescue" therapy in PD patients with "wearing off," sudden "offs," early morning akinesia, and variable response to individual doses of oral medications. Strategies for preparing and administering liquid levodopa are discussed within the context of gastric emptying, intestinal absorption, and active transport across the blood brain barrier. In addition other levodopa preparations in early development, including the orally administered levodopa methyl ester and the potential for a subcutaneously administered levodopa ethyl ester are reviewed. Furthermore, practical guidelines regarding the dosing, administration, use of the antiemetic trimethobenzamide (Tigan), time to "on," duration of benefit, and potential side effects associated with subcutaneously injected apomorphine are provided.