Vardenafil for the Treatment of Erectile Dysfunction: A Critical Review of the Literature Based on Personal Clinical Experience

Phosphodiesterase type 5 inhibition reverts prostate fibroblast-to-myofibroblast trans-differentiation

Phosphodiesterase type 5 (PDE5) inhibitors have been demonstrated to improve lower urinary tract symptoms secondary to benign prostatic hyperplasia (BPH). Because BPH is primarily driven by fibroblast-to-myofibroblast trans-differentiation, this study aimed to evaluate the potential of the PDE5 inhibitor vardenafil to inhibit and reverse trans-differentiation of primary human prostatic stromal cells (PrSC). Vardenafil, sodium nitroprusside, lentiviral-delivered short hairpin RNA-mediated PDE5 knockdown, sodium orthovanadate, and inhibitors of MAPK kinase, protein kinase G, Ras homolog family member (Rho) A, RhoA/Rho kinase, phosphatidylinositol 3 kinase and protein kinase B (AKT) were applied to PrSC treated with basic fibroblast growth factor (fibroblasts) or TGFβ1 (myofibroblasts) in vitro, in chicken chorioallantoic membrane xenografts in vivo, and to prostatic organoids ex vivo. Fibroblast-to-myofibroblast trans-differentiation was monitored by smooth muscle cell actin and IGF binding protein 3 mRNA and protein levels. Vardenafil significantly attenuated TGFβ1-induced PrSC trans-differentiation in vitro and in chorioallantoic membrane xenografts. Enhancement of nitric oxide/cyclic guanosine monophosphate signaling by vardenafil, sodium nitroprusside, or PDE5 knockdown reduced smooth muscle cell actin and IGF binding protein 3 mRNA and protein levels and restored fibroblast-like morphology in trans-differentiated myofibroblast. This reversal of trans-differentiation was not affected by MAPK kinase, protein kinase G, RhoA, or RhoA/Rho kinase inhibition, but vardenafil attenuated phospho-AKT levels in myofibroblasts. Consistently, phosphatidylinositol 3 kinase or AKT inhibition induced reversal of trans-differentiation, whereas the tyrosine phosphatase inhibitor sodium orthovanadate abrogated the effect of vardenafil. Treatment of prostatic organoids with vardenafil ex vivo reduced expression of myofibroblast markers, indicating reverse remodeling of stroma towards a desired higher fibroblast/myofibroblast ratio. Thus, enhancement of the nitric oxide/cyclic guanosine monophosphate signaling pathway by vardenafil attenuates and reverts fibroblast-to-myofibroblast trans-differentiation, hypothesizing that BPH patients might benefit from long-term therapy with PDE5 inhibitors.

The role of initial success rates and other factors in determining reliability of outcomes of phosphodiesterase inhibitor therapy for erectile dysfunction: a pooled analysis of 17 placebo-controlled trials of tadalafil for use as needed

INTRODUCTION

Reliability of successful outcomes in men with erectile dysfunction (ED) on phosphodiesterase type 5 inhibitors is an important aspect of patient management.

AIMS

We examined reliability of successful outcomes in a large integrated dataset of randomized tadalafil trials.

MAIN OUTCOME MEASURES

Success rates, time to success, subsequent success after first success, and probability of success were analyzed based on Sexual Encounter Profile questions 2 and 3.

METHODS

Data from 3,254 ED patients treated with tadalafil 10 mg (N = 510), 20 mg (N = 1,772), or placebo (N = 972) were pooled from 17 placebo-controlled studies.

RESULTS

Tadalafil patients had significantly higher first-attempt success rates vs. placebo. This effect was consistent across most subgroups; however, patients with severe ED experienced a greater response to tadalafil than patients with mild-moderate ED. Approximately 80% of patients achieved successful penile insertion within two attempts with either tadalafil dose and successful intercourse within eight attempts for tadalafil 10 mg and four attempts for tadalafil 20 mg. However, approximately 70% of tadalafil-treated patients achieved successful intercourse even by the second attempt. Subsequent success rates were higher for patients with first-attempt success (81.5% for 10 mg and 86.1% for 20 mg vs. 66.2% for placebo, P < 0.001) vs. patients with later initial success (53.2% for 10 mg and 56.4% for 20 mg vs. 39.9% for placebo, P < 0.001). Among patients treated with tadalafil, intercourse success rates at early attempts were similar to rates at later attempts (i.e., attempts 5 and 10 vs. 25), although insertion success rates were significantly lower earlier in treatment.

CONCLUSIONS

The findings affirm the reliability of successful outcomes with tadalafil treatment and that first-attempt success is a critical factor affecting subsequent outcomes. The results further show that even among men who did not succeed on first attempt, a substantial proportion will have successful outcomes if treatment is maintained.

Vardenafil for the treatment of erectile dysfunction: an overview of the clinical evidence

Many men with erectile dysfunction (ED) also have associated underlying cardiovascular and metabolic conditions, for which they are likely to be taking medication. Therefore, cardiovascular safety and potential drug interactions are two of the major concerns when using PDE-5 inhibitors in these patients. The PDE-5 inhibitor, vardenafil, is characterized by a rapid onset of action, increased duration of erection, high rates of first-dose success and reliable efficacy that can be maintained with continued use. In both clinical trials and real-life observational studies, vardenafil has demonstrated a favorable efficacy and safety profile in men with ED, including those with associated underlying conditions such as diabetes, hypertension and dyslipidemia. Importantly, the concomitant use of medication for these conditions is not associated with any noteworthy changes in the efficacy and safety of vardenafil. The evidence presented in this review supports the use of vardenafil as a first-line treatment for men with ED, including those with underlying conditions.

Cavernous neurotomy in the rat is associated with the onset of an overt condition of hypogonadism

BACKGROUND

Most men following radical retropubic prostatectomy (RRP) are afflicted by erectile dysfunction (ED). RRP-related ED occurs as a result of surgically elicited neuropraxia, leading to histological changes in the penis, including collagenization of smooth muscle and endothelial damage.

AIM

To verify whether hypogonadism could contribute to the pathogenesis of RRP-ED.

METHODS

Effects of testosterone (T), alone or in association with long-term tadalafil (Tad) treatment in a rat model of bilateral cavernous neurotomy (BCN).

MAIN OUTCOME MEASURES

Penile tissues from rats were harvested for vasoreactivity studies 3 months post-BCN. Penile oxygenation was evaluated by hypoxyprobe immunostaining. Phosphodiesterase type 5 (PDE5), endothelial nitric oxide synthase (eNOS), and neuronal nitric oxide synthase (nNOS) mRNA expression were quantified by Real Time quantitative reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS

In BCN rats, we observed the onset of an overt condition of hypogonadism, characterized by reduced T plasma level, reduced ventral prostate weight, reduced testis function (including testis weight and number of Leydig cells), with an inadequate compensatory increase of luteinizing hormone. BCN induced massive penile hypoxia, decreased muscle/fiber ratio, nNOS, eNOS, PDE5 expression, increased sensitivity to the nitric oxide donor, sodium nitroprusside (SNP), and reduced the relaxant response to acetylcholine (Ach), as well as unresponsiveness to acute Tad dosing. In BCN rats, chronic Tad-administration normalizes penile oxygenation, smooth muscle loss, PDE5 expression, SNP sensitivity, and the responsiveness to the acute Tad administration. Chronic Tad treatment was ineffective in counteracting the reduction of nNOS and eNOS expression, along with Ach responsiveness. T supplementation, in combination with Tad, reverted some of the aforementioned alterations, restoring smooth muscle content, eNOS expression, as well as the relaxant response of penile strips to Ach, but not nNOS expression.

CONCLUSION

BCN was associated with hypogonadism, probably of central origin. T supplementation in hypogonadal BCN rats ameliorates some aspects of BCN-induced ED, including collagenization of penile smooth muscle and endothelial dysfunction, except surgically induced altered nNOS expression.

Acceptance of and Discontinuation Rate from Erectile Dysfunction Oral Treatment in Patients following Bilateral Nerve-Sparing Radical Prostatectomy

OBJECTIVES

Assess acceptance of and discontinuation rate from erectile dysfunction (ED) treatment in patients after bilateral nerve-sparing radical retropubic prostatectomy (BNSRRP).

METHODS

We analyzed acceptance and discontinuation data of 100 consecutive, age-comparable, preoperatively self-reported potent BNSRRP patients who at the discharge from the hospital received a phosphodiesterase type 5 inhibitor (PDE5-I) prescription. Patients were informed of the pharmacokinetic properties of the available compounds and the option of on-demand versus rehabilitative therapy. Thereafter, patients did not receive any specific counseling throughout the entire follow-up period and freely decided to use or not use any ED therapy. Complete preoperative data were obtained on hospital admission and included a medical and sexual history and the International Index of Erectile Function (IIEF). The IIEF was completed every 6 mo postoperatively, and patients participated in a semi-structured interview about the treatment adherence at the 18-mo follow-up.

RESULTS

Forty-nine (49%) patients freely decided not to start any ED therapy (group 1). Of the remaining patients, 36 (36%) opted for an as-needed PDE5-I (group 2), whereas 15 (15%) decided to use a daily PDE5-I (group 3). At the 18-mo follow-up, the overall discontinuation rate from both treatment modalities was 72.6% (eg, 72.2% vs. 73.3% in group 2 vs. group 3; p=0.79). Treatment effect below expectations was the main reason for treatment discontinuation, followed by loss of interest in sex due to partner's causes.

CONCLUSIONS

Almost 50% of BNSRRP patients freely decided not to start any ED treatment postoperatively. Roughly 73% of patients who started therapy eventually discontinued it.

Daily vardenafil for 6 months has no detrimental effects on semen characteristics or reproductive hormones in men with normal baseline levels

PURPOSE

Phosphodiesterase type 5 inhibitors are the first choice therapy in the treatment of erectile dysfunction. Many men in their reproductive years are now using phosphodiesterase type 5 inhibitors. The purpose of this study was to determine the effects of 6 months of treatment with 20 mg vardenafil, compared with 100 mg sildenafil and placebo, on semen characteristics and reproductive hormones in men with and without erectile dysfunction.

MATERIALS AND METHODS

This was a randomized, double-blind, placebo controlled, parallel group, multicenter study. A total of 200 men with or without erectile dysfunction, able to produce semen samples without erectile dysfunction therapy, 25 to 64 years old, were randomized to daily treatment with vardenafil, sildenafil or placebo for 6 months. The primary variable was the percentage of vardenafil treated individuals with a 50% or greater decrease in mean sperm concentration from baseline to 6-month last observation carried forward, compared with placebo treated individuals.

RESULTS

The between group difference (vardenafil minus placebo) in the percentage of patients with 50% or greater decrease in sperm concentration (baseline to 6 months last observation carried forward) was 0.07% (95% CI, -8.53% to 8.39%). Vardenafil also had no clinically significant effects on any other semen parameters, or on levels of reproductive hormones, when compared with placebo. Similar data were observed with sildenafil.

CONCLUSIONS

This study demonstrated that vardenafil had no adverse effects on sperm concentration, compared with sildenafil and placebo, when administered daily at the maximum recommended dose for 6 months. Specifically, use of vardenafil for 6 months does not impair sperm concentration, total sperm count per ejaculate, or sperm morphology and motility. Levels of reproductive hormones were also unaffected.

Giving patients with erectile dysfunction the opportunity to try all three available phosphodiesterase type 5 inhibitors contributes to better long-term treatment compliance

INTRODUCTION

There are three phosphodiesterase type 5 (PDE5) inhibitors marketed, sildenafil, Vardenafil, and tadalafil for oral treatment of erectile dysfunction (ED). Although the treatment is simple and mostly effective, around 50% has ceased to use the medication within 2 years. One recently described way to improve the compliance is to let the patient try all the three PDE5 inhibitors and to prescribe the drug(s) he and his partner desires.

AIM

To study long-term compliance among patients who were treated according to this "three-drug regime."

MAIN OUTCOME MEASURES

Compliance and reasons for discontinuation after >2 years.

METHODS

The men who, during 2003, were enrolled in a treatment regime, where they had the opportunity to test all the three drugs and to chose the one(s) they preferred, were interviewed in 2006 by telephone concerning their ongoing ED treatment and the reason for discontinuation.

RESULTS

Of the 138 men, mean age 60 years (36-79 years), who had been enrolled and successfully treated with the three-drug regime, 127 (92%) could be reached. The mean follow-up time was 27 months (23-34 months). Of the 127 men, as many as 109 (86%) were still using PDE5 inhibitors. A few (8%) used more than two tablets per week. The majority (44%) used one to two tablets per week or one to two per month (43%), the others (5%) less often. The causes for discontinuation were varying. The most common reason (N = 7) was return of a satisfactory non-assisted erection. Seventy-five percent of the men used only one drug; the others switched between a short- and long-acting drug depending on the situation. It was not uncommon (25%) that the preference had changed during the 3 years of PDE5 inhibitor use.

CONCLUSION

To let patients with ED test the three available PDE5 inhibitors results in an unusually high compliance even under an extended period of time (>2 years).

Improvement in erectile function on vardenafil treatment correlates with treatment satisfaction in both patients and their partners

OBJECTIVE

To evaluate the effect of vardenafil on both erectile function (EF) and treatment satisfaction (an aspect of quality of life) in men and their partners, as erectile dysfunction (ED) has a profound effect on patients' quality of life and that of their partners, and treatment for ED tends to be focused on improving functional measures of EF.

PATIENTS, SUBJECTS AND METHODS

For this randomized, double-blind, placebo-controlled trial, men with ED for >6 months, according to the USA National Institutes of Health Consensus Statement, were recruited. In all, 611 patients were randomized to treatment with either vardenafil (10 mg for 4 weeks, titrated to preferred dose, 5, 10 or 20 mg, during the next 8 weeks, and maintained at preferred dose for the following 14 weeks), or placebo.

RESULTS

At 18 weeks (primary endpoint), the mean improvement in the EF domain of International Index of EF (IIEF-EF) vs baseline was significantly greater with vardenafil than placebo (12.70 vs 1.69, P < 0.001). This was accompanied by significant benefits at 26 weeks and in various secondary variables relating to sexual satisfaction. Qualitative assessment of the treatment effect revealed three categories of importance to patients: effectiveness, confidence and quality of life. There were significant linear correlations between patients' EF and treatment satisfaction, and between patients' EF and their partners' treatment satisfaction.

CONCLUSIONS

Functional improvements in response to vardenafil treatment are significantly correlated with treatment satisfaction for both patients with ED and their partners. These findings apply to patients with a wide range of baseline characteristics.

How long do patients with erectile dysfunction continue to use sildenafil citrate? Dropout rate from treatment course as outcome in real life

OBJECTIVES

To study the dropout rate for use of sildenafil after initial prescription and during successful treatment to clarify their risk factors.

METHODS

A total of 1036 patients with erectile dysfunction who were treated with sildenafil were analyzed. The dropout rate during successful treatment and its risk factors were assessed using the Kaplan-Meier method and Cox proportional hazards model, respectively.

RESULTS

Thirty-one percent (n = 322) of the patients dropped out after the initial prescription. The cumulative dropout rate during successful treatment at 3 years after starting usage was 48%. A lower International Index of Erectile Function (IIEF-5) score before treatment was a significant risk factor for dropout during a successful treatment course (P < 0.029 by the Cox proportional hazards model).

CONCLUSIONS

Approximately 30% and 50% of the patients dropped out of treatment after the first prescription and at 3-year follow-up, respectively. Adequate initial instruction and long-term follow-up are required even for patients with successful treatment.

The COUPLES-project: a pooled analysis of patient and partner treatment satisfaction scale (TSS) outcomes following vardenafil treatment

OBJECTIVE

To assess the influence of vardenafil on treatment satisfaction in men with erectile dysfunction (ED) and their female partners.

PATIENTS AND METHODS

This was a pooled analysis of three randomized, double-blind, placebo-controlled, 12-week studies of flexible-dose vardenafil vs placebo, in men with ED for >/=6 months (n = 788) and their untreated female partners. Measures of efficacy included the Treatment Satisfaction Scale (TSS), International Index of Erectile Function, Erectile Function domain (IIEF-EF), and Sexual Encounter Profile (SEP) questions 2 and 3 (SEP-2, 'Were you able to insert your penis into your partner's vagina?'; and SEP-3, 'Did your erection last long enough for you to have sexual intercourse?'). In addition to the overall analysis, there was a subgroup analysis for potential moderators of response, e.g. whether patients who had undergone previous phosphodiesterase type 5 (PDE-5) treatment.

RESULTS

At baseline, least-squares (LS) mean scores for all TSS domains were similar in the vardenafil and placebo groups. After 12 weeks of treatment, vardenafil significantly improved the LS mean score for all domains compared with placebo, among both patients and their female partners (P < 0.0001, 'last'-observation-carried- forward analysis). Absolute between- group differences in LS mean TSS scores (vardenafil - placebo) were: ease of erection (patients 23.4, partners 24.9), erectile function satisfaction (36.7 and 32.9), pleasure from sexual activity (23.0, 23.7), satisfaction with orgasm (27.6, 21.8), confidence to complete sexual activity (28.2, 32.5), and satisfaction with medication (37.4, 35.6). The benefits of vardenafil were greater in men who had undergone previous PDE-5-inhibitor treatment and men aged <45 years, while the overall pattern of benefit was similar in all examined subgroups. There were significant benefits with vardenafil in all other variables (IIEF-EF scores and positive response rates to SEP-2 and SEP-3).

CONCLUSIONS

Vardenafil significantly improved treatment satisfaction in men with ED, and in their partners. The results provide further evidence of the validity of the TSS.

Post-marketing surveillance study of the efficacy and safety of vardenafil among patients with erectile dysfunction in primary care

To evaluate the safety and efficacy of vardenafil in primary care, we undertook a post-marketing surveillance study in 384 men with erectile dysfunction (ED), enrolled by 22 family physicians in Korea, from July 2004 to August 2005. Of the 384 patients enrolled, 343 (89.3%) returned for efficacy assessment and safety evaluation. Among the latter, 279 patients (81.3%) reported that their erectile function improved, 292 (92.1%) showed enhanced IIEF (International Index of Erectile Function)-5 scores and 265 (77.9%) responded that they were 'very satisfied' or 'satisfied' with vardenafil treatment. The most frequent reason for patient satisfaction with vardenafil was erectile potency (62.4%), followed by safety (42.4%), rapid onset (35.3%), adequate duration of efficacy (28.5%) and easy administration (25.9%). A total of 23 adverse events were observed in 18 patients, with the most frequent being hot flushes (3.2%), followed by headache (1.2%), nasal congestion (0.6%), color vision disturbance (0.3%), dizziness (0.3%), dry mouth (0.3%), dyspepsia (0.3%), nausea (0.3%) and diarrhea (0.3%). Only one patient discontinued vardenafil as a direct result of an adverse event. These results suggest that vardenafil prescribed by primary care physicians improved erectile function and was well tolerated by patients with ED.

Predictors of Tadalafil Efficacy in Men with Erectile Dysfunction: The SURE Study Comparing Two Dosing Regimens

INTRODUCTION

The efficacy of phosphodiesterase-5 inhibitors in the treatment of erectile dysfunction may depend on patient characteristics.

AIM

To determine whether patient characteristics influence the efficacy of two tadalafil dosage regimens and to identify prognostic factors predictive of tadalafil efficacy.

METHODS

This was a multicenter, open-label study in which men with erectile dysfunction were randomized to tadalafil 20 mg either on demand or three times per week for a period of 5-6 weeks. After a 1-week washout period, patients were crossed over to the alternate regimen for another 5-6 weeks.

MAIN OUTCOME MEASURES

Score of the Erectile Function (EF) domain of the International Index of Erectile Function Questionnaire (IIEF) and percentage of positive responses to questions 3 and 5 of the Sexual Encounter Profile (SEP) diary.

RESULTS

A total of 4,262 patients were randomized. A normal EF domain score (> or =26) at the end of on-demand and three-times-per-week treatment was reported by 60.2% and 62.3% of patients, respectively. The percentage of patients who achieved a normal EF domain score and the percentages reporting positive responses to SEP3 and SEP5 depended on the severity of erectile dysfunction and the presence of certain comorbidities, irrespective of the tadalafil dosage regimen. On regression analysis, the two best predictors of tadalafil efficacy were the baseline score of the IIEF-EF domain and the baseline percentage of "Yes" responses to SEP2.

CONCLUSIONS

On-demand and three-times-per-week dosage regimens of tadalafil 20 mg were equally efficacious in men with erectile dysfunction. Among the possible prognostic factors tested in this study, baseline disease severity scores were the strongest predictors of efficacy endpoint scores.

Extended Duration of Efficacy of Vardenafil When Taken 8 Hours Before Intercourse: A Randomized, Double-Blind, Placebo-Controlled Study

OBJECTIVES

This study explored the efficacy of vardenafil in men with erectile dysfunction (ED) when taken 8 hours before sexual intercourse.

METHODS

A 10-week, randomized, double-blind, placebo-controlled, parallel-group, flexible-dose study of vardenafil (5, 10 or 20mg) was conducted in men with ED for >6 months who failed >or=50% of intercourse attempts during a 4-week treatment-free run-in period. Sexual Encounter Profile Question 3 (SEP3) was the primary efficacy measure; secondary measures included SEP2, International Index of Erectile Function-Erectile Function (IIEF-EF) domain score, Global Assessment Question (GAQ), Global Confidence Question (GCQ) and Erection Quality Scale (EQS). Adverse-event and safety monitoring were conducted throughout.

RESULTS

383 patients were randomized to vardenafil (n=194) or placebo (n=189). Patients treated with vardenafil 8 hours before sexual activity achieved clinically meaningful (>or=18%) and statistically significantly greater least-squares mean per-patient SEP3 and SEP2 success rates over weeks 2-10, compared with patients receiving placebo (SEP3 69% vs 34%; SEP2 81% vs 51%; both p<0.001). SEP3 and SEP2 measures demonstrated the significant superiority of vardenafil over placebo from week 2 onwards (p<0.001). Measurements of IIEF-EF domain score, GAQ, GCQ and EQS showed that vardenafil led to significantly greater improvements in erectile function, compared with placebo (all p<0.001). Vardenafil was generally well tolerated.

CONCLUSIONS

The extended duration of efficacy of vardenafil up to 8 hours postdose may provide couples with more flexibility in their sexual life than anticipated.

Phosphodiesterase type 5 inhibitors: the day after

OBJECTIVE

Review the literature on phosphodiesterase type 5 inhibitors (PDE5-Is), addressing critical issues in their current and future use, assessing unanswered questions, and identifying research needs.

METHODS

A MEDLINE search was conducted on PDE5-Is, with emphasis on clinical trials and experience, for interpretation and analysis of their present and future role.

RESULTS

Although approximately 40 million patients with erectile dysfunction have been treated successfully worldwide with the three available PDE5-Is, inappropriate instructions, lack of follow-up, and lack of patient-centered care models are the main reasons for "non-response," leading to drop-out rates of >50%. Patients with severe neurologic damage, diabetes mellitus, or severe vascular disease may be resistant to PDE5-Is. Preservation of corporal smooth muscle with chronic administration of PDE5-Is has been reported and substantial evidence indicates that these drugs have beneficial effects on endothelium and cardiovascular function; sildenafil has been approved for the treatment of idiopathic pulmonary hypertension. Improvement of lower urinary tract symptoms in men with benign prostatic hyperplasia after PDE5-I administration has been also suggested.

CONCLUSIONS

The data indicate the necessity for (1) exploration of the pharmacologic characteristics of the three PDE5-Is; (2) research on their pharmacologic differences because some actions seems to be drug-specific; (3) development of alternative management strategies, such as chronic, low, everyday doses of PDE5-Is, if the monthly cost is affordable; and (4) clinical trials on use of PDE5-Is to treat other chronic conditions. The door for innovative therapeutic approaches will open, specifically for cross-risk factor treatment with PDE5-Is or their use in combination treatments or new multimodal pills that take advantage of drugs that exert pleiotropic vascular actions.

Testosterone and erectile function in hypogonadal men unresponsive to tadalafil: results from an open-label uncontrolled study

The study was aimed at investigating the efficacy of tadalafil (Cialis) in combination with transdermal testosterone (Testogel) for the treatment of tadalafil-refractory erectile dysfunction in hypogonadal patients. In an open-label, retrospective trial, 69 hypogonadal nonresponders to tadalafil monotherapy (mean age: 59 years, total testosterone < or =3.4 ng ml(-1)) were randomly divided into two homogeneous groups. Group I (n = 35) received Testogel (5 g containing 50 mg testosterone, daily) for 4 weeks, followed by concurrent therapy with tadalafil (20 mg, twice a week). Group II (n = 34) was assigned to treatment with Testogel (5 g containing 50 mg testosterone, daily) for a duration of 10 weeks before adjunctive therapy with tadalafil was initiated. Total testosterone levels were measured at baseline, week 4 and week 10. Sexual function was assessed employing the International Index of Erectile Function (IIEF). As an additional measure of efficacy, a questionnaire completed by the patients' partner was used. Mean testosterone levels were observed to increase from baseline to study end. Following 4 weeks of therapy, an improvement in Erectile Function (EF) from baseline was observed, which was greater in group I than in group II. The assessment after week 10 showed that EF had further increased and was quite similar now in both groups. Partners found that erectile capacity had greatly improved from baseline to study end. No adverse effects have been observed. These data suggest that combination therapy with testosterone and tadalafil is an effective means in a subset of hypogonadal patients who did not respond to tadalafil alone. We assume that testosterone-induced remodelling of penile tissue structure is one underlying reason for the observed improvement of erectile function. The results imply that this process may require a longer period of testosterone administration than 4 weeks.

JNJ-10280205 and JNJ-10287069: novel PDE5 inhibitors as clinical candidates for erectile dysfunction

Phosphodiesterase 5 (PDE5) inhibitors are efficacious in treating patients with erectile dysfunction. New PDE5 inhibitors with different selectivity and pharmacokinetic profiles have been vigorously pursued. Here we report two novel, potent, and selective PDE5 inhibitors, JNJ-10280205 and JNJ-10287069, with Ki values of 0.05 and 0.12 nM, respectively. Both compounds displayed superior selectivity against PDE1-4 and -6 when compared to sildenafil. In the anesthetized dogs, JNJ-10280205 and JNJ-10287069 exhibited similar efficacy as sildenafil in enhancing erectile functions, with no significant effect on cardiovascular parameters. Pharmacokinetic studies showed that JNJ-10287069 had better oral bioavailability than JNJ-10280205 in several animal species. In vitro study suggested that cytochrome P450 (CYP) 3A4 played a major role in the metabolism of both compounds. The compounds inhibited some of the CYP450 enzymes and the human ether-a-go-go (HERG) channel at much higher concentrations than that required to inhibit PDE5, thus, no cross inhibition would be expected at therapeutic doses. Both compounds are suitable clinical candidates.

Prescribing all phosphodiesterase 5 inhibitors to a patient with erectile dysfunction--a realistic and feasible option in everyday clinical practice--outcomes of a simple treatment regime

OBJECTIVE

In clinical practice, to apply and evaluate outcomes of a treatment regime, in which the patient had the opportunity to try all the available phosphodiesterase 5 (PDE5) inhibitors.

METHODS

Patients eligible for treatment with PDE5 inhibitors were prescribed 8 tablets with a shorter-acting substance (four tablets sildenafil 100mg and four tablets vardenafil 20mg) and eight tablets with a long-acting substance (tadalafil 20mg). Outcomes of the regime were recorded.

RESULTS

Of the 186 patients, 64 (34%) had not been treated previously (naïve), and 122 (66%) were undergoing treatment for their erectile dysfunction. The overall treatment response was 89% (165 of 186 patients); 78% (n=145 of 186 patients) tested all three substances. No significant difference in choice between long- and shorter-acting medications in the overall material was observed. Two thirds of the naïve patients (n=64) preferred a shorter-acting substance (p<0.01). Every fifth man requested both a shorter- and a long-acting medication to accommodate his need.

CONCLUSION

If patients are given the opportunity in clinical practice to try all three available PDE5 inhibitors, the overall response rate is very high, almost 90%. No significant difference in patient preference between long- and shorter-acting drugs was observed. Treatment choice was based mainly on efficacy or duration of effect.

Phosphodiesterase 11: a brief review of structure, expression and function

Phosphodiesterase 11 (PDE11) is the latest isoform of the phosphodiesterase family to be identified. Interest in PDE11 has increased recently because tadalafil, an oral phosphodiesterase 5 inhibitor, cross reacts with PDE11. The function of PDE11 remains largely unknown, but growing evidence points to a possible role in male reproduction. The published literature on PDE11 structure, function and expression is reviewed.