some medications cause urinary retention, either by inhibiting bladder contractility or by increasing bladder outlet resistance, namely anticholinergics and sympathomimetic agents. medications that cause retention by inhibiting bladder contractility include antispasmodic agents (oxybutynin chloride, belladonna, and opioid suppositories) and tricyclic antidepressant medications (imipramine, doxepin). Medications that cause urine retention by increasing bladder outlet resistance include alpha-adrenergic agents (ephedrine sulfate, pseudoephedrine), beta-adrenergic blockers (pro-pranolol), and estrogens.