Efficacy and Safety of Paroxetine Controlled Release for Major Depressive Disorder in Irritable Bowel Syndrome Patients

This is an open label, randomized, add-on, 8 weeks multicentre study to evaluate the efficacy and safety of paroxetine CR in patients with MDD comorbid IBS. This study is designed with a 1-week screening period, followed by 8 weeks of treatment and 1 week follow up period, 7 visits totally; the calculation of visit date is base on the real date of random date. Study Screening: Visit 1: a screening period for within 7 days to determine eligibility for the study, subjects aged ≥ 18 and ≤ 65 years at the time of screening, must have a diagnosis of IBS and MDD. After giving their informed consent to participate in the study, patients will undergo screening assessments, including demographic data (birth, race, gender, height, weight), medical history, disease history, therapy history, concomitant medication, physical examination, vital signs, 12-lead ECG and laboratory assessments. Treatment Phase: The treatment phase will last for 8 weeks. The visit (except baseline) will have ±3 days. Visit 2 (Day 0, baseline visit): Patients who fulfil all the study inclusion and exclusion criteria will accept baseline assessment (including concomitant medication, vital signs and scale assessment) and be randomised into paroxetine CR plus IBS regular treatment group or IBS regular treatment only group at baseline visit. The day after randomizing (Day 1), patients will receive paroxetine CR 12.5mg/d plus IBS regular treatment or IBS regular treatment only (patients who have received IBS regular treatment before can continue their treatment). On Day 8, following 1 weeks of treatment, paroxetine CR should be titrated to 25mg/d. Visit 3-5 (Day 14, Day 28, Day 42): Efficacy and safety assessments will be performed at these visits, including vital signs and HDRS-17 (Hamilton Depression Rating Scale 17 items), CGI-S (Clinical Global Impression- Severity), CGI-I (Clinical Global Impression- Improvement), WHOQOL (World Health Organization Quality of Life Assessment), IBSSS (The Irritable Bowel Severity Scoring System). From Week 3 to 6, the investigator can titrate the subject's dose upwards according to clinical response and tolerability, at a maximum rate of paroxetine CR 12.5mg every 14 days. For example, if CGI-I is ≥3 based on the assessment at scheduled clinic visit, and the patient is able to tolerate an increased dose, the dose increment to the next dose level shall be considered. The highest dose that may be administered is paroxetine CR 50 mg and dose titration may only occur at scheduled visits. Visit 6 (Day 56): Efficacy and safety assessments will be performed at these visits, including vital signs, physical examination, laboratory assessments and HDRS-17, CGI-S, CGI-I, WHOQOL, IBSSS. If the patient experiences an adverse event (AE) and the investigator deems that a reduction in dose is required then the patient may be administered a dose one level (paroxetine CR 12.5 mg) lower than they were taking previously. Upon resolution of the AE, the investigator may return to patient's pre-AE dose level. Follow-Up: After treatment phase, the investigator should communicate with all the subjects about the follow-up choice: reduce or continuing paroxetine CR treatment/ other antidepressants treatment/ transferring to psychiatric clinics. It is not recommend to reduce drug dosage during the treatment period of MDD. For those subjects who decide to discontinue paroxetine CR treatment: a gradual reduction in the dose rather than abrupt cessation is recommended whenever possible. The dosage should be reduced weekly, the daily dose reduction is 12.5mg per week, and once a week. If intolerable symptoms occur following a decrease in the dose or upon discontinuation of treatment, then resuming the previously prescribed dose may be considered. Subsequently, the physician may continue decreasing the dose but at a more gradual rate. Visit 7 (Day 63): the investigator should conduct safety follow up by phone call to all participants to investigate the medication situation and safety related information. Withdraw: Patients withdrawn from the study prior to Visit 6 (Week 8) will have all end-of-study procedures performed. Patients withdrawn from the study for any reason are to attend an early withdrawal visit on withdrawal from the study. In addition, patients have to taper the study drug if they end the study on a dose level higher than dose level 1 (paroxetine CR 12.5 mg). The dosage should be reduced weekly, the daily dose reduction is 12.5mg per week, and once a week.