['chronic constipation']
['linaclotide', 'placebo']

        Inclusion Criteria:

          -  Patients with SBM frequency for < 3 times/week, since ≥ 6 months prior to preliminary
             enrollment

          -  Patients with one or more related symptoms for ≥ 6 months prior to preliminary
             enrollment

          -  Patients at whom loose (mushy) or watery stools are rarely present without the use of
             laxatives for ≥ 6 months prior to preliminary enrollment

          -  Patients who underwent pancolonoscopy or contrast enema after development of the CC
             symptoms and within 5 years prior to preliminary enrollment, and in whom no organic
             change was observed which dose not influence on CC symptoms

          -  Female patients must be either:

        If of non-childbearing potential:

          -  Post-menopausal at the preliminary enrollment, or documented surgically sterile Or, if
             of childbearing potential,

          -  Agree not to try to become pregnant during the study and for 28 days after the final
             study drug administration

          -  And have a negative urine pregnancy test at screening

          -  And, if heterosexually active, agree to consistently use two forms of highly effective
             birth control throughout the study period and for 28 days after the final study drug
             administration

               -  Female patients must agree not to breastfeed throughout the study period and for
                  28 days after the final study drug administration

               -  Female patients must not donate ova starting throughout the study period and for
                  28 days after the final study drug administration

               -  Male subject and their female spouse/partners who are of childbearing potential
                  must be using two forms of highly effective form of birth control starting at
                  Screening and continue throughout the study period, and for 28 days after the
                  final study drug administration

               -  Male subject must not donate sperm starting at Screening and throughout the study
                  period and, for 28 days after the final study drug administration

        Exclusion Criteria:

          -  Patients who have met the Rome III diagnostic criteria for IBS; with recurrent
             abdominal pain or discomfort for ≥ 3 days/month in the last 3 months prior to
             preliminary enrollment, associated with ≥ 2 of the 3 characteristics described below
             and with the symptoms (IBS symptoms) described above for ≥ 6 months prior to
             preliminary enrollment

               1. Improvement with defecation

               2. Onset associated with a change in frequency of stool

               3. Onset associated with a change in form (appearance) of stool

          -  Patients with a history of surgical resection of the stomach, gallbladder, small
             intestine, or large intestine

          -  Patients with a history or current evidence of inflammatory bowel disease or ischemic
             colitis

          -  Patients with concurrent infectious enteritis, hyperthyroidism or hypothyroidism,
             constipation due to anorectal dysfunction, drug-induced constipation, constipation due
             to other organic diseases or active peptic ulcer

          -  Patients with apparent mechanical obstruction

          -  Patients with megacolon or megarectum

          -  For female patients, patients with concurrent endometriosis or adenomyosis

          -  Patients who are considered to have severe depression or a severe anxiety disorder
             that can affect the efficacy evaluation of the study drug

          -  Patients with a history of abuse of drugs or alcohol, or current abuse of drugs or
             alcohol

          -  Patients who used/underwent or are scheduled to use/undergo prohibited concomitant
             drugs or therapies, or in whom prohibited examinations were conducted or are scheduled
             to be conducted 3 days prior to the start of the bowel habit observation period

          -  Patients with a history or current evidence of malignant tumors

          -  Patients with concurrent serious cardiovascular diseases, respiratory diseases, renal
             diseases, hepatic diseases, gastrointestinal disorders, blood diseases, or
             neurological/psychiatric diseases

          -  Patients with a history of drug allergies

          -  Patients who have participated in the clinical trial of ASP0456 or have been
             administered ASP0456

          -  Patients who have participated or are participating in another clinical trial or
             post-marketing clinical study of other ethical drugs or medical devices within 12
             weeks prior to obtaining informed consent
      