Vardenafil Effect on Ureteric Smooth Muscle: In Vitro Study in Porcine Model

Inhibition of PDE-4 isoenzyme attenuates frequency and overall contractility of agonist-evoked ureteral phasic contractions

The aim of this study was to investigate the functional role of phosphodiesterase enzymes (PDE) in the isolated porcine ureter. Distal ureteral strips were mounted in organ baths and pre-contracted with 5-HT (100 μM). Upon generation of stable phasic contractions, PDE-4 and PDE-5 inhibitors were added cumulatively to separate tissues. PDE-4 inhibitors, such as rolipram (10 nM and greater) and roflumilast (100 nM and greater), resulted in significant attenuation of ureteral contractile responses, while a higher concentration of piclamilast (1 μM and greater) was required to induce a significant depressant effect. The attenuation effect by rolipram was abolished by SQ22536 (100 μM). PDE-5 inhibitors, such as sildenafil and tadalafil, were not nearly as effective and were only able to suppress the 5-HT-induced contractions at higher concentrations of 1 μM. Rolipram significantly enhanced the depressant effect of forskolin, while sodium nitroprusside-induced attenuation of contractile responses remained unchanged in the presence of tadalafil. In summary, our study demonstrates that PDE-4 inhibitors are effective in attenuating 5-HT-induced contractility in porcine distal ureteral tissues, while PDE-5 inhibitors are less effective. These findings suggest that PDE-4 inhibitors, such as rolipram, may hold promise as potential therapeutic agents for the treatment of ureteral disorders attributable to increased intra-ureteral pressure.

Efficacy of phosphodiesterase type 5 inhibitors for the treatment of distal ureteral calculi: A systematic review and meta-analysis

PURPOSE

To determine the efficacy of phosphodiesterase type 5 inhibitors (PDE5i) as medical expulsive therapy (MET) for the treatment of distal ureteral calculi.

MATERIALS AND METHODS

A search strategy was conducted in the MEDLINE, CENTRAL, and Embase databases. Searches were also conducted in other databases and unpublished literature. Clinical trials were included without language restrictions. The risk of bias was evaluated with the Cochrane Collaboration's tool. An analysis of random effects due to statistical heterogeneity was conducted. The primary outcome was the expulsion rate of the distal ureteral calculus in 28 days. The secondary outcomes were the time to expulsion, side effects of treatment, and amount (mg) of nonopioid analgesia. The measure of the effect was the risk difference (RD) with a 95% confidence interval (CI). The planned interventions were PDE5i vs. placebo, tadalafil vs. placebo, and tadalafil vs. tamsulosin.

RESULTS

Four articles were included in the qualitative and quantitative analysis. Records of 580 patients were found among the four studies. A low risk of bias was shown for the majority of the study items. The calculi expulsion rate had an RD of 0.26 (95% CI, 0.15-0.37) and a less prolonged expulsion as a secondary outcome with a mean difference of -4.39 days (95% CI, -6.69 to -2.09) in favor of PDE5i compared with the placebo. No significant difference was found for these outcomes when comparing tadalafil with tamsulosin.

CONCLUSIONS

Compared with a placebo, PDE5i could be effective as MET for the treatment of distal ureter calculi.

In vitro Evaluation of Ureteral Contractility: A Comparative Assessment of Human, Porcine and Sheep Ureteral Response to Vardenafil

Objectives: Basic science studies of ureteral physiology and pathophysiology are commonly performed on animal ureters due to several limitations associated with human ureteral sampling. In this work we question whether animal ureters are good replicas of human ureteral behavior for pharmacological studies. Materials and Methods: Ureteral rings from human, porcine and ovine ureters underwent the same organ bath protocol. After stimulation with KCl, ureters were subjected to different doses of vardenafil. Basic contractility and ureteral response to vardenafil were analyzed. Results: A different pattern of basic contractility was evidenced between species. Vardenafil administration induced a dose-dependent reduction in KCl-induced amplitude increase in human ureters and a dose-dependent reduction in autonomic contractile rhythm of porcine and ovine ureters. Although animal ureters could predict the relaxant response of human samples to vardenafil, its effect would have been overestimated using only animal models. Conclusions: Human ureteral investigations cannot entirely be replaced by existing animal models since results of the latter will vary significantly according to the tested pharmaceutical agent.