Tolerability, Pharmacokinetics, and Efficacy of APD371 in Participants With Crohn's Disease Experiencing Abdominal Pain

Key Inclusion Criteria: * A clinical diagnosis of Crohn's disease for at least 3 months prior to screening corroborated by prior endoscopic and histopathologic documentation consistent with Crohn's disease. * Quiescent to mildly active inflammatory Crohn's disease defined with a total of simple endoscopy score for Crohn's disease (SES-CD) score of \< 10 or fecal calprotectin \< 500 mcg/g within 4 weeks before Screening. * Moderate to severe abdominal pain as defined by average abdominal pain score (AAPS) of \>/= 4points on 7 consecutive days of the screening period up to Day -2. AAPS will be based on the 11-point numeric rating scale where 0 (no abdominal pain) to 10 (worst possible abdominal pain). Key Exclusion Criteria: * Female participants who are lactating or have a positive serum pregnancy test during the screening period or a positive urine pregnancy test on Day 1 prior to study drug administration. * Recent history (within 6 months of screening visit) of cerebrovascular disease, Acute Coronary Syndrome, Cerebrovascular accident, Transient ischemic attack, Myocardial infarction, unstable angina. * Other significant chronic pain conditions that in the opinion of the Investigator may influence the abdominal pain score. * History of extensive colonic resection, subtotal or total colectomy. * History of \>3 small bowel resections or diagnosis of short bowel syndrome or who have undergone bowel resection within 6 months prior to randomization. * Chronic active hepatitis B within the last year (unless shown at the time of study entry to be hepatitis B antigen negative) or any history of hepatitis C. * Evidence of current gastro-intestinal infection (bacterial or parasitic) or significant infection within 45 days of screening. Note: other protocol defined Inclusion/Exclusion criteria may apply.