Lisdexamfetamine and Urinary Retention

Mechanism of Action

Lisdexamfetamine is a prodrug that converts to dextroamphetamine in the body, which acts as a sympathomimetic agent stimulating alpha-adrenergic receptors throughout the lower urinary tract, according to the American Journal of Obstetrics and Gynecology 1
Stimulation of alpha-adrenergic receptors in the bladder neck and urethra causes smooth muscle contraction and increased outlet resistance, potentially leading to urinary retention, as reported by The Journal of Urology 2
The high concentration of alpha-adrenergic receptors at the bladder neck and throughout the urethra makes these areas particularly susceptible to the effects of sympathomimetic drugs like amphetamines, as noted by The Journal of Urology 2

Patients taking lisdexamfetamine may experience sensation of incomplete bladder emptying, increased post-void residual urine volume, as reported by The Journal of Urology 2

Male gender is a risk factor for urinary retention due to anatomical differences in urethral length and presence of prostate, according to The Journal of Urology 3
Pre-existing lower urinary tract symptoms and concurrent use of other medications with anticholinergic properties increase the risk of urinary retention, as reported by The Journal of Urology 3 and 4
Benign prostatic hyperplasia in older males is also a risk factor, as noted by The Journal of Urology 3 and 5

For patients experiencing urinary symptoms while on lisdexamfetamine, dose reduction may be considered if symptoms are mild, as suggested by the American Journal of Obstetrics and Gynecology 1
Alpha-blockers, such as tamsulosin, may be considered to counteract the alpha-adrenergic stimulation caused by lisdexamfetamine, as reported by The Journal of Urology 2 and 3

Patients starting lisdexamfetamine should be monitored for development of new urinary symptoms, increased post-void residual urine volume, and changes in urinary flow patterns, as recommended by The Journal of Urology 2

Urinary symptoms may be misattributed to other causes, especially in older males with BPH, as noted by The Journal of Urology 3 and 5
Concurrent use of other medications affecting urinary function can exacerbate urinary retention, as reported by The Journal of Urology 4
Patients may not spontaneously report mild urinary symptoms, making direct questioning important, as suggested by The Journal of Urology 2