Efficacy and Safety of Lubiprostone in the Treatment of Slow Transit Constipation

Inclusion Criteria: 1. Patients voluntarily participated in the study and provided signed informed consent; 2. Met the Rome IV diagnostic criteria for functional constipation; 3. Had fewer than 3 spontaneous bowel movements (SBMs) per week; 4. More than 20% the radio-paque markers localized in the colon after 72 hours based on colonic transit studies; 5. Were able to complete the bowel movement diary and study questionnaires as required by the study protocol; 6. Agreed to use effective contraception from the time of signing the informed consent form until 3 months after the last dose of the study drug; 7. Aged 18 years or older, both males and females. Exclusion Criteria: 1. Pregnant or lactating women. 2. Patients with severe outlet obstruction constipation (e.g. Oxford Grade IV or above for rectal prolapse, rectocele \> 3.1 cm, puborectalis syndrome). 3. Patients with hyperthyroidism or hypothyroidism. 4. Patients with opioid-induced constipation. 5. Patients with megacolon or megarectum. 6. Patients with apparent mechanical intestinal obstruction. 7. Patients with inflammatory bowel disease (e.g. Crohn's disease or ulcerative colitis). 8. Patients with malignant tumors of the digestive system. 9. Patients with a history of colorectal surgery. 10. Patients with a previous history of taking lubiprostone. 11. Patients with severe symptoms of depression or anxiety. 12. Patients with known or suspected hypersensitivity to lubiprostone/polyethylene glycol 4000 or any excipients. 13. Patients requiring medications for Parkinson's disease, antipsychotics, antimanic agents, or psychostimulants. 14. Patients with severe cardiovascular, respiratory, renal, hepatic, gastrointestinal, hematologic, neurological, or psychiatric diseases. 15. Other patients deemed by the investigator as unsuitable for participation in this trial.