Mechanical blinding (encapsulation) was used to ensure the double-blind nature of the study. Because the patients enrolled in the trial received levodopa/benserazide in different doses, over-encapsulation of tablets permitted blinding of most oral dosage forms: ½ tablet, several small tablets, capsules of different sizes or colors. Each capsule was then be placed in a narrow opaque tube and identified as "Treatment 1" and "Treatment 2" before administration to the patient. The patient, the investigator, Medical Monitor and Clinical Monitor remained blinded, whereas the site pharmacist and a nurse who administered study medication were not blind throughout this part of the study.