The anticholinergic activity of agents indicated for urinary incontinence is an important property for effective...

The anticholinergic, antispasmodic and local anesthetic properties of agents indicated for the treatment of neurogenic bladder disorders were compared with known reference drugs in vitro and in cystometric studies in vivo in the guinea pig. Highly significant correlations (P = .0001) were found among the potencies of drugs to inhibit carbachol-induced isolated guinea pig detrusor muscle contraction in vitro and peak intravesical bladder pressure in vivo in the guinea pig cystometrogram, a test that provides the integrated micturition response in the intact animal. In contrast, there was no significant correlation (P greater than .5) among the potencies of the drugs to depress bladder contractile responses (in vitro and in vivo in the cystometrogram) and their potencies as antispasmodic or local anesthetic agents. Based on these correlations, we suggest that the anticholinergic component of the drugs' action is important in current effective therapies of bladder dysfunction. However, the possibility that other ancillary activities may also contribute to the specific mechanism of action of these agents in the urinary bladder is not ruled out.