2009 update on phosphodiesterase type 5 inhibitor therapy part 1: Recent studies on routine dosing for penile rehabilitation, lower urinary tract symptoms, and other indications (CME).
BACKGROUND
Highly selective inhibitors of phosphodiesterase type 5 (PDE5I) have been commercially available for over a decade. Our knowledge of these drugs continues to expand.


OBJECTIVE
To review developments within the past 18 months on the utilization of PDE5I in preclinical studies and clinical practice. The focus of this article is on updates on regular dosing regimens of PDE5I other than the newly approved daily dose tadalafil.


METHODS
PubMed search utilizing the terms "phosphodiesterase type 5 inhibitor," PDE5 inhibitor,""sildenafil,""vardenafil," and "tadalafil." Articles were screened based on whether or not they addressed issues of routine dosing of PDE5I. Manuscripts on the newly approved daily dose tadalafil for erectile dysfunction (ED) were deferred for analysis in a separate manuscript in this series.


METHODS
Peer reviewed publications on routine dosing of PDE5I published in the medical literature since 2007.


RESULTS
There have been numerous publications in the past 2 years regarding routine dosing of PDE5I for three major urological indications; penile rehabilitation, stuttering priapism, and management of lower urinary tract symptoms (LUTS). Evidence from basic science investigations has indicated that daily dose PDE5I may improve erectile function and exert a number of beneficial tissue effects on the penis. Unfortunately, data from human series of routine dose PDE5I for penile rehabilitation after radical prostatectomy are conflicting, with the two largest studies showing no benefit to daily dose therapy in the post-radical prostatectomy and the general ED populations. PDE5I are generally helpful at reducing symptoms of LUTS, particularly when given in conjunction with alpha blockers. Routine dosing of PDE5I has also been utilized successfully for management of stuttering ischemic priapism and several other medical indications.


CONCLUSIONS
PDE5I given as routine doses have clinical promise. Further research is required to clarify their safety and efficacy for various indications.
Shindel
Alan W
AW
Department of Urology, University of California-San Francisco, 400 Parnassus St., San Francisco, CA 94143-0738, USA. shindela@urology.ucsf.edu
D006801:Humans; D007093:Imidazoles / Q000627:therapeutic use; D018783:Impotence, Vasculogenic / Q000188:drug therapy*; D008297:Male; D010413:Penis / Q000098:blood supply / Q000187:drug effects*; D010726:Phosphodiesterase Inhibitors / Q000627:therapeutic use*; D010879:Piperazines / Q000627:therapeutic use; D011317:Priapism / Q000188:drug therapy*; D011468:Prostatectomy / Q000009:adverse effects; D011687:Purines / Q000627:therapeutic use; D055502:Secondary Prevention; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000627:therapeutic use; D014227:Triazines / Q000627:therapeutic use; D014570:Urologic Diseases / Q000188:drug therapy*; D000069058:Vardenafil Dihydrochloride; D014665:Vasodilator Agents / Q000627:therapeutic use
D007093:Imidazoles; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014227:Triazines; D014665:Vasodilator Agents; D000069058:Vardenafil Dihydrochloride; D000068677:Sildenafil Citrate