This is a single-center trial that enrolls 20 18 to 85-year-old patients with moderate to severe FC to study the efficacy of Vibrabot capsule (dosage: 5 capsules/week) and polyethylene glycol, as well as the mechanism of action of the Vibrabot capsule.

This study is a prospective, parallel controlled clinical trial. Subjects are considered eligible for this study if they meet the inclusion criteria and do not meet any of the exclusion criteria. They must sign an Ethics Committee (EC)-approved Informed Consent Form (ICF) and be randomly assigned to trial group 1, trial group 2 and control group for the respective treatment.

Subjects in Trial Group 1 received polyethylene glycol combined with Vibrabot capsules for 2 weeks and then Vibrabot capsules for 4 weeks; Subjects in Trial Group 2 received Vibrabot capsules for 12 consecutive weeks; Subjects in the control group received polyethylene glycol for 6 weeks, and subjects with poor efficacy could voluntarily choose to continue to receive Vibrabot capsules for 6 weeks. During the treatment period, the dosage of Vibrabot capsule is 1 capsule/time, 5 times/week, and that of polyethylene glycol is 10g/time, twice/day. The subjects who receive Vibrabot capsules will undergo a colonic transit study, a radionuclide imaging-based gastrointestinal transit assessment, an anorectal manometry, a neurotransmitter test, and a fecal flora test before and after the treatment. After completion of treatment, subjects in each group entered a follow-up period, which was observed until the patient regained symptoms of constipation, i.e., when laxatives or other bowel-promoting treatments were used. If the subject never recovered from constipation, a minimum of 8 weeks of questionnaire completion was required, depending on the patient's compliance status. During the study period, the subjects are required to keep an e-diary recording daily bowel movements (BMs), medication intake, and discomforts, and complete the Patient Assessment of Constipation-Symptoms (PAC-SYM) and the Patient Assessment of Constipation Quality of Life (PAC-QOL) questionnaires every two weeks.

This study consists of a screening/baseline period, a treatment period and a follow-up period. During the study, subjects are required not to change their diet and lifestyle. The washout or follow-up period will end once the subject uses rescue medication. If subjects have no BM for three or more consecutive days, they are permitted to take bisacodyl as rescue medication. If they cannot tolerate bisacodyl, an enema may be used instead. They should avoid antibiotics, probiotics, prebiotics, and proton pump inhibitors throughout their participation in the study.

Inclusion Criteria:

1. People with moderate to severe functional constipation according to Rome IV criteria.
2. People who agree to use appropriate medical methods of contraception from the time they sign the ICF until the end of the treatment period (excluding women in a medical sterilization status).
3. People who had a colonoscopy within three years before screening and negative results, or their colonoscopy results are judged by the investigator as mild anomalies, but the cause of their constipation cannot be explained. If the colonoscopy report is unavailable, the study physician will determine if a colonoscopy is needed. If the subjects undergo a colonoscopy after signing the ICF, they will not enter the treatment period until their BMs return to the baseline level.
4. People had colonic polyps and a polypectomy (except for endoscopic submucosal dissection (ESD)): Those with a polyp ≤1 cm can be enrolled one month after the polypectomy; Those with a polyp >1 cm can be enrolled three months after the polypectomy.
5. People who consent to participate in this trial and can communicate with the investigator and can understand and comply with the relevant procedures and requirements during the study (including completing study questionnaires on time, being treated and visited as scheduled, and undergoing relevant examinations), and voluntarily sign the ICF.

Exclusion Criteria:

1. People who are not eligible for surgery or refuse to undergo any abdominal surgery.
2. People with known or suspected gastrointestinal obstruction, stenosis, diverticulum, bleeding, malformation, and fistula.
3. People allergic to polymeric materials.
4. People implanted with cardiac pacemakers and using gastrointestinal pacemakers.
5. People with abdominal aortic aneurysms, gastrointestinal vascular lesions, ulcers, and lesions with bleeding tendencies.
6. People with dysphagia.
7. Pregnant women or women with pregnancy plans in the next year.
8. People with severe depression and anxiety and severe acute gastrointestinal lesions.
9. People who had gastrointestinal surgery or a history of surgery that changed the structure of the gastrointestinal tract (except for appendectomy) or people who underwent gastrointestinal ESD in the past three months.
10. People with severe hemorrhoids (patients with grade III-IV hemorrhoids according to the Clinical Practice Guidelines for the Management of Hemorrhoids of the American Society of Colon and Rectal Surgeons).
11. People who plan to undergo MRI in the near future.
12. People with other conditions, so the investigator considers them not eligible for this study.