Eligibility Criteria:
Inclusion Criteria:
* ambulatory male or female with no history or current evidence of other conditions or abnormalities that would affect study results or interfere with participation for full duration of study
* meets diagnostic criteria for functional constipation. This includes loose stools that are rarely present without the use of laxatives and 2 or more of the following: straining during at least 25% of defecations; lumpy or hard stools in at least 25% of defecations; sensation of incomplete evacuation for at least 25% of defecations; sensation of anorectal obstruction/blockage for at least 25% of defecations; manual maneuvers to facilitate at least 25% of defecations \[e.g., digital evacuation, support of the pelvic floor\]; and fewer than 3 defecations per week. Criteria for functional constipation must be fulfilled for last 3 months, with symptom onset at least 6 months prior to diagnosis.
* continuous or recurrent symptoms for at least 3 months of: abdominal pain or discomfort, relieved with defecation, or associated with a change in frequency or consistency of stool, and an irregular pattern of defecation at least 25% of the time with 3 or more of the following: altered stool frequency, altered stool form (hard or loose/watery), altered stool passage (straining or urgency, feeling of incomplete evacuation), passage of mucus, and bloating or abdominal distension
* agrees to not use laxatives other than study medication for the duration of the study period
* agrees to not use disallowed concomitant medications for the duration of the study
* agrees to maintain a similar diet and level of activity from the period of the Screening Visit through End of Study
* individuals of reproductive potential must agree to remain abstinent or use (or have their partner use) 2 acceptable methods of birth control and until 2 weeks after the last dose of study drug in the last treatment period. Acceptable methods of birth control include: intrauterine device (IUD), diaphragm with spermicide, contraceptive sponge, condom, or vasectomy.
Exclusion Criteria:
* abnormal baseline endoscopy and/or an oral exam
* baseline oral exam showing evidence of oral lesions, such as herpes labialis or aphthous stomatitis, or known self-reported history or current periodontal gum disease
* history of impaired swallowing or difficulties swallowing foods and liquids
* known, history of, or suspected gastrointenstinal disease, including bowel perforation, obstruction, fecal impaction; irritable bowel syndrome (IBS), delayed gastric emptying, gastroparesis, gastroesophageal reflux disease (GERD), gastritis or peptic ulcer disease (PUD), dehydration, inflammatory bowel disease, bowel resection, anal fistulas/fissures, colostomy, etc.
* severe or unexplained abdominal pain
* history of or current alcohol or drug abuse
* history of malignancy ≤5 years prior to signing the informed consent, except for adequately treated basal cell and/or squamous cell skin cancer or in situ cervical cancer
* history of psychiatric illness requiring medications or hospitalization within the previous 12 months
* history of concurrent illness that required hospitalization within 4 weeks prior to Day -1 of the study
* allergies or allergic reactions or intolerance to any of the products used in study
* any degree of renal impairment
* major surgery or clinically significant illness within 4 weeks prior to Day -1 of Visit 1
* current or recent (within the past 30 days of signing informed consent) participation in a study with an investigational compound or device
* refusal to agree not to donate eggs or sperm upon the first study drug administration and thereafter through 90 days after the last study drug administration
* individual is an employee or family member of an employee of the sponsor or clinical unit where study will be conducted