Update on phosphodiesterase (PDE) isoenzymes as pharmacologic targets in urology: present and future

Diseases of the human urinary tract represent common morbidities characterized by a high prevalence in the population of most westernized countries. The existence of a significant number of affected patients and the recent increase in scientific attention has resulted in various experimental and clinical efforts in order to evaluate the mechanisms controlling the function of urinary tract organs. This review attempts to describe the physiology and pharmacology of phosphodiesterase (PDE) isoenzymes with special regard to their (potential) use in disorders of the human urogenital tract.

The promising clinical data for the orally active phosphodiesterase (PDE) inhibitors sildenafil, vardenafil and tadalafil, used in the treatment of male erectile dysfunction (MED), has boosted research activities on the significance of the cyclic GMP- and cyclic AMP pathway in other genitourinary tract tissues, such as the bladder, prostate, ureter, urethra, as well as female genital tissues. Based on the more extensive understanding of the pathways controlling the function of the male and female urogenital tract, orally administered phosphodiesterase inhibitors are considered a logical and straightforward approach for treating urological diseases. Due to the unending charge to conceive advanced first-line treatments, new therapeutic options taking into consideration the cyclic nucleotide signaling have been introduced or might be launched in the near future. Upcoming strategies will not only focus on the nitric oxide (NO)/cGMP cascade but also on compounds modulating signal transduction mediated by cyclic adenosine monophosphate, as well as combined agents in order to affect multiple peripheral intracellular targets.

The article highlights cGMP- and cAMP-pathways, PDE subtypes and their present or putative future clinical significance in urological practice.