Carbidopa-levodopa (CD-LD) is the mainstay of treatment for Parkinson's disease (PD), yet most patients with advanced PD develop motor fluctuations with time when treated with CD-LD. Development of longer-acting CD-LD formulations is a major goal for reducing motor fluctuations in advanced PD. IPX066 is a new formulation of CD-LD that contains both an immediate-release and a sustained-release levodopa component, which is currently under review by the US FDA. Recent clinical trials have demonstrated improved effectiveness of IPX066 compared with other CD-LD formulations in advanced PD, with a reduction in 'off' time of approximately 37%. While it has also been shown to be effective in early PD compared with placebo, its role in early PD compared with other available medications for PD is unclear at this time.