Overactive bladder (OAB) is characterized by urinary urgency with or without urge urinary incontinence, usually with frequency and nocturia, in the absence of urinary tract infection or other obvious pathology. Antimuscarinic agents such as solifenacin are commonly used but may provide incomplete symptom control. Tadalafil (a Phosphodiesterase type 5 inhibitorsinhibitor) has been reported to improve lower urinary tract symptoms and may offer additional benefit in overactive bladder. This randomized controlled trial evaluates the efficacy and tolerability of solifenacin 5 mg plus tadalafil 5 mg versus solifenacin 5 mg alone in females with overactive bladder using the Overactive Bladder Symptom Score (OABSS).

Inclusion Criteria:

• Female patients aged 18 to 60 years.
• Symptoms of overactive bladder for more than 6 months.
• Not receiving current medical treatment for overactive bladder.
• Normal liver function tests.
• Normal kidney function.

Exclusion Criteria:

• Congestive heart failure or history of recent cardiovascular events.
• Currently on medical treatment for overactive bladder.
• Urinary tract infection (eligible only after treatment and resolution).
• Urinary bladder stones.
• Post-void residual urine > 100 cubic centimeter (cm³).
• Closed-angle glaucoma or recent ocular problems.
• Postural hypotension.
• History of neurological disorders (e.g., parkinsonism).
• History of intestinal obstruction.
• Pregnancy or planning pregnancy.
• Myasthenia gravis.
• Severe hepatic impairment.
• History of hypersensitivity to solifenacin or tadalafil.

De-identified individual participant data (IPD) underlying the reported results (including OABSS total and domain scores and adverse event data) and a data dictionary will be made available to qualified researchers upon reasonable request.

Beginning after publication of the primary results (or thesis acceptance) and available for (e.g., 5 years).

Requests should include a brief proposal and analysis plan. Access will be provided after review and approval by the study investigators/department and execution of a data use agreement. Data will be shared in a secure format.