A commonly missed symptom in Parkinson's patients is constipation. Constipation can be difficult to treat with current medications available and many are ineffective. Levodopa and dopamine agonists drugs are useful for motor symptoms in Parkinson's Disease but have no effect on constipation. Laxatives and enemas provide limited relief with bothersome side effects. Even fewer drugs have been studied targeting the constipation problem specifically in the Parkinson's Disease population. Lubiprostone (AMITIZA) is a new medication that has been studied in the general population for the treatment of chronic constipation. It has been shown to be a safe and effective medication with few side effects. Lubiprostone has not yet been studied in the Parkinson's Disease population. We hope to show that this medication can be safe and effective for constipation in PD patients as well.