Study of Carbetocin Nasal Spray for the Treatment of Hyperphagia in Prader-Willi Syndrome

Inclusion Criteria * Male or female and 5 through 30 years of age * Prader-Willi syndrome with a documented disease-causing mutation * Increased appetite with decreased satiety accompanied by food seeking (consistent with PWS Nutritional Phase 3) * HQ-CT total score of ≥13 at Screening and Baseline * CGI-S score for hyperphagia in PWS of ≥4 at Screening and Baseline * Lives with a caregiver who understands and is willing and able to adhere to study-related procedures and is willing to participate in all study visits Exclusion Criteria * Genetically diagnosed with Schaaf-Yang syndrome or another genetic, hormonal, or chromosomal cognitive impairment besides PWS * An active upper respiratory infection at the Screening visit or the Baseline visit * Any clinically significant cardiovascular disorder, renal, hepatic, gastrointestinal, or respiratory disease, including severe asthma * History of, or current, cerebrovascular disease, brain trauma, epilepsy, or frequent migraines. A history of febrile seizures is not exclusionary * Nasal surgery within 1 month of Screening visit or planning to have nasal surgery during the study. * Unwilling to abstain from nasal saline, other nasal irrigation, and other intranasal medications during the Screening period and through the treatment period of the study * Clinically significant irritability or agitation, requiring initiation of or increase in the dose of antipsychotic medication, within the 6 months prior to the Screening visit * Used prostaglandins, prostaglandin analogues, or prostaglandin agonists in the 3 months prior to the Baseline visit. Inhibitors of prostaglandin synthesis, such as nonsteroidal anti-inflammatory drugs, are not exclusionary. * Started a glucagon-like peptide 1 (GLP-1) agonist within the 6 months prior to the Screening visit. Treatment with GLP-1 agonist is allowed if the subject has been taking it for more than 6 months prior to Screening. * Used oxytocin, desmopressin (DDAVP), tesofensine, diazoxide choline, melanocortin-4 receptor (MC4R) agonists (e.g., setmelanotide), or any medication approved to treat hyperphagia within 6 months prior to the Baseline visit * Active psychotic symptoms, a history of psychotic symptoms, or a psychotic disorder * History of suicide attempt or inpatient psychiatric hospitalization * New food-related interventions, including environment or dietary restrictions, within 1 month prior to the Screening visit or during the Screening period (i.e., before the Baseline visit) Additional inclusion/exclusion criteria apply. Subjects will be evaluated at screening to ensure that all criteria for study participation are met.