This is a Phase 2, open-label study to investigate the effects of ARD-101 in subjects with Prader-Willi Syndrome. This study has a planned enrollment of 12 subjects and will be conducted in a single center in the United States.The study will consist of a Screening Period (up to 28 days), a Treatment Period (28 days), and a Follow-up Period (End-of-Study Visit within 14 days after receiving the last dose of ARD-101). The screening procedures will be initiated upon completion of the informed consent process. Following completion of screening procedures and confirmation of eligibility, subjects will be enrolled to receive ARD-101 in an outpatient setting and will be instructed to visit the clinical center periodically for safety and efficacy assessments.