The second Princeton consensus on sexual dysfunction and cardiac risk: new guidelines for sexual medicine

Erectile Dysfunction: Monitoring Response to Treatment in Clinical Practice—Recommendations of an International Study Panel

INTRODUCTION

Clinical practice guidelines for management of erectile dysfunction (ED) provide limited direction in defining appropriate treatment goals with phosphodiesterase type 5 (PDE5) inhibitor therapy.

AIM

To establish an evidence-based position on treatment goals in ED, including the role of erection hardness, with the potential to improve self-esteem, confidence, and overall sexual and relationship satisfaction.

MAIN OUTCOME MEASURE

The target of ED therapy is optimization of a rigid erectile response, as assessed by the 4-point Erection Hardness Score (EHS). Methods. An international panel of experts in urology, psychology, and primary care convened to evaluate retrospective data from worldwide phase 2, 3, and 4 clinical trials, involving over 10,000 men with ED, as well as data from recent prospective studies, concerning the role of erection hardness in defining the response to treatment with PDE5 therapy.

RESULTS

Significant positive correlations were found between EHS and the Quality of Erection Questionnaire and the International Index of Erectile Function (IIEF) erectile function domain score and other IIEF measures. Significant positive correlations were also found between erection hardness and psychosocial measures such as self-esteem, confidence, and relationship satisfaction (assessed by the Self-Esteem And Relationship questionnaire), and satisfaction with medical treatment (assessed by the Erectile Dysfunction Inventory of Treatment Satisfaction). A shift in most frequent erection from EHS 3 (hard enough for penetration but not fully hard) at baseline to EHS 4 (completely hard and fully rigid) at the end of treatment was accompanied by significant improvements in intercourse and relationship satisfaction, psychosocial benefits, and satisfaction with ED treatment.

CONCLUSIONS

Support is found for monitoring and treating patients with ED to their full erectile potential. Quantitative assessment of erection hardness in clinical practice will lead to improved outcomes in overall sexual experience and optimal treatment satisfaction.

hMaxi-K Gene Transfer in Males with Erectile Dysfunction: Results of the First Human Trial

Eleven patients with moderate to severe erectile dysfunction (ED) were given a single-dose corpus cavernosum injection of hMaxi-K, a "naked" DNA plasmid carrying the human cDNA encoding hSlo (for human slow-poke), the gene for the alpha, or pore-forming, subunit of the human smooth muscle Maxi-K channel. Three patients each were given 500, 1000, and 5000 microg, and two patients were given 7500 microg, of hMaxi-K and monitored for 24 weeks. The primary objectives of this phase I study were safety and tolerability of escalating hMaxi-K doses as assessed by clinical evaluations and laboratory tests. Secondary efficacy objectives were measured primarily by use of the International Index of Erectile Function (IIEF) scale. Patient responses were validated by partner responses. There were no serious adverse events and no dose-related adverse events attributed to gene transfer for any patient at any dose or study visit. No clinically significant changes from baseline were seen in physical evaluations (general and genitourinary), hematology, chemistry, and hormone analyses, or in cardiac events evaluated by repeated electrocardiograms. Importantly, no plasmid was detected in the semen of patients at any time after the injections. Patients given the two highest doses of hMaxi-K had apparent sustained improvements in erectile function (EF) as indicated by improved IIEF-EF domain scores over the length of the study. One patient given 5000 microg and one given 7500 microg reported EF category improvements that were highly clinically significant and were also maintained through the 24 weeks of study. Efficacy conclusions cannot be drawn from results of a phase I trial with no control group. However, the promising primary safety outcomes of the study and preliminary indications of effectiveness provide evidence that hMaxi-K gene transfer is a viable approach to the treatment of ED and that further studies investigating the efficacy of hMaxi-K in patients with ED should be performed.

Overexpression of arginase in the aged mouse penis impairs erectile function and decreases eNOS activity: influence of in vivo gene therapy of anti-arginase

Since both increased nitric oxide (NO) synthase (NOS) abundance and diminished NO signaling have been reported in the aging penis, the role of NO in the adaptations of aging remains controversial. Here we tested the hypothesis that arginase, an enzyme that competes with NOS for the substrate l-arginine, contributes to erectile dysfunction with advanced age in the B6/129 mouse strain. Arginase protein abundance, mRNA expression, and enzyme activity were elevated in aged compared with young penile endothelial cells. In addition, endothelial NOS (NOS3) protein abundance was greater in aged versus young penile endothelial cells, whereas NOS activity and cGMP levels were reduced. Calcium-dependent l-arginine-to-l-citrulline conversion and cGMP formation increased significantly in aged mouse penes in the presence of the arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH). However, there was no effect on l-arginine-to-l-citrulline conversion or cGMP accumulation in the endothelium from young mouse penes. To assess the functional role of arginase in the inhibition of NOS pathway responsiveness in the penis, we evaluated the effects of ABH and an adeno-associated virus encoding an antisense sequence to arginase I (AAVanti-arginase) on erectile function in vivo. ABH and AAVanti-arginase enhanced endothelium-dependent erectile responses in the aged mice without altering endothelium-independent responses. Paralleling our in vitro observations, ABH or AAVanti-arginase did not affect vascular responses in the young mice. Inhibition of the arginase pathway improves endothelial function in the aging penile circulation, suggesting that the arginase pathway may be exploited to improve erectile dysfunction associated with aging.