Safety and Tolerability of Oral Polyethylene Glycol (PEG 3350) Solution in Participants With Constipation (MK-8114-003)

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