The goal of this double-blind, randomized, placebo-controlled study is to evaluate whether oxybutynin chloride extended-release tablets can improve early continence recovery after robot-assisted radical prostatectomy (RARP) in patients with localized prostate cancer.

The main questions it aims to answer are:

[Does oxybutynin chloride improve continence recovery after RARP compared to a placebo?] [What are the predictors of continence recovery?]

Researchers will compare the treatment group (oxybutynin chloride 10 mg/day) with the control group (placebo) to assess differences in continence outcomes.

Participants will:

[Take the assigned medication (oxybutynin chloride or placebo) daily for 1-3 months until continence recovery.] [Complete surveys (e.g., IPSS, IIEF, ICIQ) at several time points post-surgery, including before surgery, 10 days after Foley catheter removal, and up to 12 months.] [Record any adverse events or concomitant medication use.]

Safety and tolerability will be monitored, and statistical analyses will determine the efficacy and predictors of continence. The study adheres to ethical principles, local regulations, and GCP guidelines.

Extended Description of the Protocol This study is a double-blind, randomized, placebo-controlled clinical trial designed to evaluate the efficacy of oxybutynin chloride extended-release tablets (Oxbu) in improving early continence recovery following robot-assisted radical prostatectomy (RARP) in patients with localized prostate cancer.

Study Design and Structure

The study involves 135 patients, with 120 expected to complete all study procedures. Participants will be randomly assigned to one of two groups:

Treatment group: Receives 10 mg/day of oxybutynin chloride extended-release tablets.

Control group: Receives a placebo (identical in appearance to active drug). The treatment period lasts from 1 to 3 months, or until participants achieve complete continence, defined as no need for urinary pads and less than one episode of incontinence per week.

Intervention and Administration Dosage: Two tablets (5 mg each) taken orally once daily for both treatment and control groups.

Concomitant medications:

Prohibited: α-receptor blockers, cholinergics, and anticholinergics, among others.

Permitted: Acetaminophen and antacids, provided they are documented and do not interfere with the study objectives.

Data Collection and Efficacy Evaluation

Participants' continence outcomes will be assessed through standardized tools, including:

International Prostate Symptom Score (IPSS) International Index of Erectile Function (IIEF) International Consultation on Incontinence Questionnaire (ICIQ) Measurements will occur at baseline (pre-surgery), 10 days post-Foley catheter removal, and at intervals up to 12 months post-surgery.

Safety Monitoring All adverse events (AEs) will be recorded, with severity and relationship to the study medication assessed. AEs will be documented in Case Report Forms (CRFs) and reviewed for safety monitoring.

Statistical Analysis

Statistical analysis will involve:

Continuous variables: Assessed using independent t-tests or Mann-Whitney U tests.

Categorical variables: Compared via chi-squared, Fisher's exact tests, or linear-by-linear association tests.

Predictor analysis: Logistic regression (univariate and multivariate). Significance: p-values < 0.05. Ethical Considerations The study complies with the Declaration of Helsinki, Good Clinical Practice (GCP), and local regulations. Ethical committee approval is required before enrolling participants, and all patients must provide written informed consent prior to participation.

Timeline Enrollment period: 12 months. Treatment duration: 1-3 months. Study completion: Approximately 42 months. This extended protocol description highlights key technical aspects, intervention methods, and analytical strategies while avoiding duplication of eligibility and outcome measures previously outlined.

Inclusion Criteria:

• Diagnosis: Patients with localized prostate cancer who are scheduled to undergo robot-assisted radical prostatectomy (RARP).
• Age: Participants must be 18 years or older, with no upper age limit.
• Consent: Participants must provide written informed consent before undergoing any study procedures.
• Ability to Follow Protocol: Participants must be able to follow the protocol procedures throughout the study.

Exclusion Criteria:

• Surgical Complications: Participants who experience surgical complications during or after RARP requiring extraordinary medical or surgical treatment.
• Other Urinary Conditions: Participants with other diseases causing lower urinary tract symptoms (LUTS) or bladder pain, including:
• - Benign prostatic hyperplasia (BPH), chronic prostatitis, interstitial cystitis, painful bladder syndrome, or urinary tract infection.
• - Overactive bladder or any other condition affecting bladder function.
• Chronic Medication: Participants with long-term use of medications such as:
• - Alpha-blockers, antimuscarinics, or anticholinergics.
• Glaucoma: Participants with narrow-angle glaucoma.
• Urinary Retention: Participants with a history of urinary retention.
• Gastrointestinal Motility Issues: Participants with severe conditions affecting gastrointestinal motility.
• Concurrent Medications: Participants who are taking medications that are prohibited by the study protocol (e.g., cholinergic drugs, azole antifungals, smooth muscle relaxants).

In this study, study coordinators and data analysts are also masked to ensure that there is no bias in the data collection and analysis process. This further ensures that the evaluation of outcomes, such as the effectiveness of the treatment and the assessment of adverse events, is unbiased and objective.