26 Week Efficacy and Safety Trial for Patients With Chronic Idiopathic Constipation

Inclusion Criteria: * Body mass index (BMI) ≥18.5 but \<35.0 kg/m\^2 * Male or female ≥18 years of age * Reports \<3 spontaneous Bowel movements (BM) per week and reports one or more of the following symptoms for the last 3 months with symptom onset at least 6 months before the Screening Visit or before starting chronic therapy with any laxative: 1. Straining during at least 25% of defecations 2. Lumpy or hard stools during at least 25% of defecations 3. Sensation of incomplete evacuation during at least 25% of defecations * Is ambulatory and community dwelling * An initial colonoscopy is required if recommended by national guidelines Exclusion Criteria: * Reports loose (mushy) or watery stools in the absence of any laxative intake in the form of a tablet, a suppository or an enema, or prohibited medicine for \>25% of BMs * The patient reports a BSFS of 6 or 7 during the Pretreatment Period * Has irritable bowel syndrome (IBS) with pain/discomfort as predominant symptoms * Has a structural abnormality of the GI tract or a disease or condition that can affect Gastrointestinal (GI) motility * Has a history of diverticulitis, chronic pancreatitis, active peptic ulcer disease (PUD) not adequately treated, ischaemic colitis, inflammatory bowel disease, laxative abuse, faecal impaction that required hospitalization or emergency treatment, pseudo-obstruction, megacolon, megarectum, bowel obstruction, descending perineum syndrome, ovarian cysts, endometriosis, solitary rectal ulcer syndrome, systemic sclerosis, pre-malignant colonic disease (e.g., familial adenomatous polyposis or hereditary non-polyposis colorectal cancer) or other forms of familial colorectal cancer. * Has unexplained and clinically significant GI alarm signals (e.g., lower GI bleeding or heme-positive stool in the absence of known internal or external haemorrhoids, iron-deficiency anaemia, unexplained weight loss) or systemic signs of infection or colitis * Has a potential central nervous system (CNS) cause of constipation (e.g., Parkinson's disease, spinal cord injury, multiple sclerosis) * Has intestinal/rectal prolapse or other known pelvic floor dysfunction * Commonly uses digital manoeuvres (perianal pressure or digital disimpaction) or vaginal splinting to facilitate the passage of a bowel movement * Has a history of diabetic neuropathy * Has a history of bariatric surgery for treatment of obesity; surgery to remove a segment of the GI tract; or surgery of the abdomen, pelvic or retroperitoneal area during the 6 months prior to Screening; or appendectomy or cholecystectomy 3 months prior to screening; or other major surgery 1 month prior to Screening * Has a history of cancer with last date of proven disease activity/presence of malignancy within 5 years, except for adequately treated basal cell carcinoma of the skin, cervical dysplasia, or carcinoma in situ of the skin or the cervix * Known human immunodeficiency virus (HIV) or Hepatitis B/C (HBV/HCV) infection * Has a history of hospitalization for any psychiatric disorder, or any suicide attempt in the 2 years prior to Screening * Is actively abusing alcohol or drugs or has a history of alcohol or drug abuse during the 6 months prior to Screening * Is being treated for hypothyroidism, but the dose of medication has not been stable for at least 3 months at the time of Screening * Is a pregnant, breast-feeding, or lactating woman