Comparison of the effects of various spasmolytic drugs on isolated human and porcine detrusor smooth muscle.

The spasmolytic activity of flavoxate (CAS 15301-69-6), anticholinergic agents oxybutynin (CAS 5633-20-5), and trospium chloride (CAS 10405-02-4), drugs commonly utilized in the therapy of hyperactive bladder, and phosphodiesterase (PDE) inhibitors papaverine (CAS 58-74-2) and vinpocetine (CAS 42971-09-5) on muscarinic contractions of detrusor smooth muscle strips isolated from human and porcine urinary bladder was studied in vitro using the organ bath technique. Trospium chloride was most effective in relaxing contractions elicited by muscarinic stimulation, while flavoxate was significantly less effective than all other drugs tested. The relaxing potency of oxybutynin was greater than those of PDE-inhibitors papaverine and vinpocetine but 3,000 fold less significant than those of trospium chloride. The effects of the individual drugs on muscarinic tension of both human and porcine detrusor muscle strips were nearly equal. The present results suggest that the pig might be an appropriate animal model for the study of effects of spasmolytic substances on the contractility of urinary bladder smooth muscle in vitro.