Oxybutynin is an antispasmodic, anticholinergic agent indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency. Oxybutynin relaxes bladder smooth muscle. Oxybutynin exhibits only one-fifth of the anticholinergic activity of atropine on the rabbit detrusor muscle, but four to ten times the antispasmodic activity. Antimuscarinic activity resides predominantly in the R-isomer. Oxybutynin exerts a direct antispasmodic effect on smooth muscle and inhibits the muscarinic action of acetylcholine on smooth muscle. No blocking effects occur at skeletal neuromuscular junctions or autonomic ganglia (antinicotinic effects). By inhibiting particularily the M1 and M2 receptors of the bladder, detrusor activity is markedly decreased.

Esoxybutynin is (S)-enantiomer of oxybutynin. Esoxybutynin exerts antimuscarinic properties. Racemic oxybutynin is used clinically to treat urinary incontinence. Sepracor was developing (S)-oxybutynin, a single-isomer version of Alza's Ditropan (racemic oxybutynin), a muscarinic acetylcholine receptor antagonist, as a potential treatment for urinary incontinence.