Effects of Antimuscarinic Drugs on Ejaculation Duration and Refractory Period in Men With Overactive Bladder

Overactive bladder affects quality of life significantly and is managed with antimuscarinic agents that block M2 and M3 muscarinic receptors. M3 receptors mediate direct smooth muscle contraction via Gq protein and phospholipase C-induced calcium release, while M2 receptors modulate M3 activity indirectly via Gi protein and adenylyl cyclase inhibition.

Ejaculation consists of two phases: emission (peristaltic movement of seminal fluid from seminal vesicles and vas deferens into the prostatic urethra) and expulsion (forceful ejection from the urethra). Both M2 and M3 receptors have been identified in smooth muscle and epithelial cells of seminal vesicles in animal studies, suggesting a role in regulating peristaltic contractions during the emission phase.

This study hypothesizes that antimuscarinic drugs may prolong ejaculation duration by inhibiting peristaltic activity in the seminal vesicles and vas deferens via M2/M3 receptor blockade, thereby extending the emission phase.

Male patients aged 20-50 presenting with OAB symptoms and initiated on antimuscarinic therapy will be evaluated using IIEF, PEP, PEDT, and OAB-V8 questionnaires at baseline, 1 month, and 2 months. This is a purely observational study with no modification to standard clinical care.

Inclusion criteria

• Male patients aged 20-50 years
• Diagnosis of overactive bladder (OAB) confirmed clinically
• Sexually active
• Willing to complete questionnaires at all three time points

Exclusion criteria

• Previous use of antimuscarinic or beta-3 agonist medications
• Neurological disorders affecting bladder or sexual function (e.g., multiple sclerosis, Parkinson's disease, spinal cord injury)
• Prior pelvic surgery or radiotherapy
• Use of medications known to affect ejaculatory function (e.g., alpha-blockers, SSRIs, antipsychotics)
• Active urinary tract infection
• Uncontrolled diabetes mellitus
• Unwillingness to participate