The purpose of this is study is to evaluate the effects of DCCR (diazoxide choline controlled release tablets) in children and adults with Prader-Willi syndrome.
Inclusion Criteria: * Provide voluntary, written informed consent (parent(s) / legal guardian(s) of patient); provide voluntary, written assent (patients, as appropriate) * Genetically-confirmed Prader-Willi syndrome and hyperphagic * In a stable care setting for at least 6 months prior to Visit 1 * Caregiver must have been caring for the patient for at least 6 months prior to Visit 1 Exclusion Criteria: * Have participated in an interventional clinical study (i.e., investigational drug or device, approved drugs or device evaluated for unapproved use) within prior 3 months * Positive urine pregnancy test (in females of child-bearing potential) or females who are pregnant or breastfeeding, and/or plan to become pregnant or to breast-feed during or within 30 days after study participation * Any other known disease and/or condition, which would prevent, in the opinion of the Investigator, the patient from completing all study visits and assessments required by the protocol