Testosterone and erectile physiology

The role of testosterone deficiency in sexual dysfunction is an important aspect of aging, because it affects such a large proportion of men over 50 years old. A number of age-related factors can cause sexual dysfunction (in particular erectile dysfunction) and testosterone deficiency, such as chronic illness and multiple medications, and the causative link between hypogonadism and erectile dysfunction is still debated. However, studies in castrated animals have proven that addition of testosterone, and its conversion to dihydrotestosterone, can restore erectile function. It appears that testosterone achieves this by peripheral mechanisms (endothelial dependent and independent) and central mechanisms. Testosterone replacement therapy is therefore effective for erectile dysfunction in men with hypogonadism, with success rates of 35–40%. Testosterone supplementation is also important in men who fail on phosphodiesterase type-5 inhibitors, because a minimum plasma concentration of testosterone is required for the successful restoration of erectile function with these agents. Testosterone gels are now the preferred formulation for testosterone supplementation and they can be highly beneficial in a proportion of men with erectile dysfunction.     

Vacuum erection device in treatment of organic erectile dysfunction and penile vascular differences between patients with DM type I and DM type II

The aim of this study is to investigate changes in the vascular system and hemodynamics between patients with organic erectile dysfunction (ED) (DM type I and II), as well as to compare the quality of sexual life between those two groups after the treatment with vacuum erection device (VED). Study enrolled 50 males with DM, aged from 35 to 67 years, who have attended the urologic clinic due to inability to attain and maintain an erection of the penis sufficient to permit satisfactory sexual intercourse. Patients were using VED and six months later were assessed for therapy results. The International Index of Erectile Function (IIEF) was used to quantify erectile dysfunction. Alprostadil injection test was also used, with Doppler color flow imaging system, to evaluate the peak systolic velocity (PSV) and diameter of cavernosal artery (DCA). Significantly higher values of PSV were obtained in patients with DM type II. Also, DCA showed significant difference between two groups of patients. There was significant improvement in three items of IIEF after six months of treatment among both groups of examinees. Patients with DM type I had more serious risk for development of arteriogenic ED. VED could be a good alternative therapy for patients who denied peroral therapy.     

Testosterone therapy in erectile dysfunction

Studies in animals have indicated that the nitric oxide erectile pathway is testosterone-dependent. Castration induces erectile dysfunction and a reduction in nitric oxide synthase-stained nerves in erectile tissue. Furthermore, castration adversely affects penile hemodynamics and smooth muscle content, leading to veno-occlusive dysfunction. Testosterone replenishment reverses these physiological, biochemical and structural changes. Several clinical studies have demonstrated the benefits of a combination of testosterone and sildenafil. A recently published, multicenter study evaluated the safety and efficacy of testosterone gel 1% (Testogel®; Schering AG, Germany/AndroGel®; Solvay Pharmaceuticals) vs. placebo gel in conjunction with sildenafil, in producing an erectile response in hypogonadal men who did not respond to treatment with sildenafil alone for erectile dysfunction. The selection criteria required subjects to have had erectile dysfunction for at least 3 months, to be non-responsive to 100 mg sildenafil and to have low testosterone levels (<?400 ng/dl). The primary efficacy measurement was the mean change from baseline in the Erectile Function domain of the International Index of Erectile Function (IIEF). Secondary outcome measures included the mean change from baseline in the other domains and the total sum of the IIEF. Subjects were randomized to receive either testosterone gel + sildenafil, or placebo gel + sildenafil for 12 weeks. Testosterone therapy with testosterone gel improved the erectile response to sildenafil. Therefore, testosterone therapy may be considered for the treatment of erectile dysfunction in men with low to low-normal testosterone levels, who have failed prior treatment with sildenafil alone. Consequently, it is important to screen for hypogonadism in men who fail PDE5 inhibitors.     

Assessment of andropause awareness and erectile dysfunction among married men in Ile-Ife,Nigeria

Andropause (also known as androgen decline in aging males) has implications for the reproductive health and quality of life of older males. Very few studies have, however, been reported among the Nigerian population on andropause-related issues. This study assesses the perspective and level of awareness of married men in Ile-Ife, South-west Nigeria, of andropause. We also assessed their experience of erectile dysfunction, using a questionnaire based on the review of the International Index of Erectile Dysfunction. The study involved 355 married men, aged between 30 and 70 years. Our result shows a high level of misconception about andropause among our respondents, with 38.9% indicating that it is a myth, and another 23.6% attributing it to various causes other than being a natural aging process. We recorded a prevalence of erectile dysfunction of 43.8% (8.0% severe dysfunction and 35.8% moderate dysfunction). The prevalence of erectile dysfunction increased significantly with age, varying from 38.5% for age 31-40 years to 63.9% for the older age group of 61-70 years. The trend in prevalence of erectile dysfunction with age was significant (p < 0.05). An odds ratio of 2.82 (95% confidence interval 1.19-6.76) was recorded for the prevalence of erectile dysfunction at age 61-70 years compared with age 31-40 years. Our findings indicate a need for health education about andropause in Nigeria, and increased attention to the reproductive health concerns of males, and the older population.     

Aging and sexual health: getting to the problem

Erectile dysfunction (ED) is one of the most common disorders in male and is often associated with other age-related comorbidities. The aging process affects the structural organization and function of penile erectile components such as smooth muscle cell and vascular architecture. These modifications affect penile hemodynamics by impairing cavernosal smooth muscle cell relaxation, reducing penile elasticity, compliance and promoting fibrosis. This review aims to identify the mechanisms of ED in the penile aging process in experimental and clinical data. It also highlights areas that are in need of more research. The search strategies yielded total records screened from PubMed. Clarification of the molecular mechanisms that accompanies corpus cavernosum aging and aging-associated ED will aid new perspectives in the development of novel mechanism-based therapeutic approaches. Age is not a limiting factor for ED medical management, and it is never too late to treat. Hypogonadism should be managed regardless of age, and synergistic effects have been found during testosterone (T) replacement therapy when used along with oral phosphodiesterase-5 (PDE-5) inhibitors. Therefore, the clinical management of ED related to aging can be done by therapeutic interventions that include PDE-5 inhibitors, and other pharmacological treatments.     

Erectile dysfunction is strongly linked with decreased libido in diabetic men

Erectile dysfunction frequently occurs with diabetes mellitus. A survey of diabetic men was conducted by anonymous questionnaire to investigate the associations of erectile dysfunction with various predictive factors. A total of 112 diabetic males without an obvious history of erectile dysfunction were available for analyses. The mean age and duration of diabetes were 53.7?±?12.2 years and 10.2?±?8.6 years (mean?±?standard deviation), respectively. The questionnaire included questions on the presence or absence of smoking, hypertension, libido and subjective symptoms of diabetic neuropathy that may be associated with erectile dysfunction. Analysis of the answers to the questionnaire revealed that 40% of the patients complained of erectile dysfunction (erection ‘always insufficient’). Erectile dysfunction was significantly correlated with age (p?=?0.005), but not with duration of diabetes (p?=?0.25), adjusted for age. Erectile dysfunction was also associated with sensory neuropathy and reduced libido, independently of age. The logistic regression analysis revealed that erectile dysfunction was positively associated with reduced libido and age. The odds ratio of erectile dysfunction for reduced compared to unreduced libido was 18.21, suggesting that psychogenic factors have a marked influence on erectile dysfunction. It is concluded that the presence of erectile dysfunction should be considered when symptoms related to diabetic neuropathy are observed; psychological approaches, such as sexual counseling, could be applied for the treatment of erectile dysfunction.     

Endothelial progenitor cells and erectile dysfunction: a brief review on diagnostic significance and summary of our experience

Abstract

The article provides a brief review of the literature concerning the diagnostic use of endothelial progenitor cells in patients with erectile dysfunction. In particular, patients with arterial erectile dysfunction could benefit from the use of this diagnostic marker, which in clinical practice can be used together with more conventional methods such as the penile Doppler. It is very important to acquire diagnostic tools for the diagnosis of sub clinical form of endothelial dysfunction in these patients, in particular when the erectile dysfunction is associated with cardiovascular risk factors.     

Oral testosterone undecanoate (Andriol®) supplement therapy improves the quality of life for men with testosterone deficiency

In a single-blind, placebo-controlled study, the effects of a 3-month oral administration of 160 mg/day testosterone undecanoate (Andriol^®) on the quality of life of men with testosterone deficiency were evaluated. The subjects included ten men with primary hypogonadism and 29 with andropause with sexual dysfunction as the most common problem. The changes in subjective symptoms were evaluated by the PNUH QoL scoring system and the St. Louis University Questionnaire for androgen deficiency in aging males (ADAM). Digital rectal examination (DRE) was performed and serum testosterone, prostate-specific antigen (PSA) and liver profile were monitored. Testosterone undecanoate treatment (n = 33) significantly improved sexual dysfunction and symptom scores of metabolic, cardiopulmonary, musculo-skeletal and gastrointestinal functions compared to baseline and to placebo (n = 6). ADAM score also significantly improved after 3 months of treatment. Serum testosterone was significantly increased compared to pretreatment levels only in the testosterone undecanoate group. In the placebo group, no significant changes compared to baseline were found for testosterone levels and QoL questionnaires. No abnormal findings were detected on DRE or laboratory findings in either group. Adverse events, such as gastrointestinal problems and fatigue, were mild and self-limiting. It is concluded that androgen supplement therapy with oral testosterone undecanoate (Andriol) restores the quality of life through improvement of general body functions in men with testosterone deficiency.     

Pituitary radiographic abnormalities and clinical correlates of hypogonadism in elderly males presenting with erectile dysfunction

The prevalence of erectile dysfunction rises rapidly with age and is a frequent complaint presented in clinical practice. Although the etiology of erectile dysfunction is multifactorial, 10-20% of evaluations demonstrate testosterone deficiency. Testosterone deficiency due to secondary hypogonadism increases with age. Despite a higher prevalence of secondary hypogonadism in the elderly, there are no studies addressing hypothalamic-pituitary structural abnormalities in elderly impotent men with testosterone deficiency. We retrospectively reviewed the records of all elderly men who presented for general outpatient evaluation of erectile dysfunction from 1996 to 1999. To obtain a cohort control population, the records of 300 patients without erectile dysfunction were also reviewed. Amongst the erectile dysfunction patients, 225 were found to be testosterone deficient (testosterone < 300 ng/dl). Of these patients, 29 were additionally diagnosed with secondary hypogonadism based on a luteinizing hormone (LH) < 13 mIU/ml. Magnetic resonance imaging (MRI) or computed tomography (CT) imaging was available and reviewed in all patients diagnosed with secondary hypogonadism. Ten per cent of these patients had hypothalamic-pituitary imaging abnormalities. The prevalence of pituitary tumors within our population was not significantly elevated compared to the previous general population studies. Small-vessel white matter disease, hyperlipidemia and history of compression fractures were significantly increased in both univariate and multivariate analysis in the erectile dysfunction group compared with the control cohort. This study does not suggest that the use of hypothalamic-pituitary imaging in the evaluation of impotence in elderly men, in the absence of clinical characteristics of other hormonal loss or sella compression symptoms, will increase diagnosis of structural hypothalamic-pituitary abnormalities over that of the general population. However, the yield may increase with very low testosterone levels. These data suggest that there is an increase in ischemic white matter disease in elderly men with hypogonadism that may reflect microvascular injury to the hypothalamic-pituitary. Furthermore, these data confirm that low testosterone is associated with hyperlipidemia in the elderly. Future studies are required to assess the role of hypogonadism and hyperlipidemia, and to determine if treatment of the hormone deficiency improves the lipid profile.     

Diagnosing and treating testosterone deficiency in different parts of the world. Results from global market research

Aim. This study analysed variations between different regions of the world in diagnosing and treating testosterone (T) deficiency.

Methods. Physicians were interviewed in Germany, Spain and the United Kingdom, in Brazil, in Saudi Arabia and South Korea. Items in the survey: 1) reasons/motivation to use or not to use T; 2) what category of patients would not receive T on the basis of these concerns; 3) concerns about prostate pathology in the decision not to provide T treatment; 4) phosphodiesterase type 5 (PDE-5) inhibitors are efficacious, but T treatment makes a comeback.

Results. Between 5% and 10% of consulting patients suffered from T deficiency. The fear to induce prostate cancer appeared very powerful. About 68% of physicians associate the use of T more with risks than benefits, more so in Europe than elsewhere. As a result about 35% of hypogonadal men do not receive treatment. The PDE-5 inhibitors are very prominent in the treatment of erectile dysfunction. Of patients suffering from erectile dysfunction, 18% to 29% have T deficiency which is not always diagnosed and treated.

Conclusion. World-wide physicians require more education on diagnosing T deficiency, on the role of T in erectile dysfunction and the relative safety of testosterone treatment.     

Oral testosterone undecanoate reverses erectile dysfunction associated with diabetes mellitus in patients failing on sildenafil citrate therapy alone

Aims: To evaluate the cause of failure of sildenafil citrate (Viagra^®) to restore erections in patients with organic erectile dysfunction (ED) associated with type II diabetes mellitus (DM) and receiving oral antidiabetic drugs. Methods: Diabetic ED patients (n = 120), aged 43-74 years, failing to respond at least three times to 100 mg Viagra were evaluated. After at least 2 weeks' treatment with oral testosterone undecanoate (Andriol^®), 100 mg Viagra was used before coitus. ED was assessed with the International Index of Erectile Function (IIEF). Serum total testosterone, prolactin, thyroid stimulating hormone, lipid profile and prostate-specific antigen (PSA) were determined by standard methods and prostate volume by digital rectal examination. Age-matched diabetic ED patients (n = 100) served as controls for baseline values. Results: Viagra non-responders had, at baseline, significantly lower testosterone and more depressed libido than controls. Andriol restored testosterone to normal levels and increased libido. In 84/120 (70%) Viagra non-responders, combined therapy with Andriol induced satisfactory erections, a significant increase in IIEF scale (question (Q) 3 from 2.0 ± 0.2 to 3.7 ± 0.3, Q4 from 1.9 ± 0.1 to 3.4 ± 0.2, Q12 from 1.0 ± 0.1 to 4.2 ± 0.4) and increased sexual contacts from 0.5 to 3-4 per month. No adverse events were noted, and PSA levels remained below 4 ng/ml. Conclusion: Decreased testosterone levels in patients with ED and type II DM receiving oral antidiabetic agents may be responsible for failure to respond to sildenafil citrate therapy. Combination with oral testosterone undecanoate restores sexual function in these patients.     

A prospective longitudinal survey of erectile function status in symptomatic benign prostatic hyperplasia patients treated with dutasteride

We prospectively evaluated erectile function (EF) using the Sexual Health Inventory for Men (SHIM) and the erectile hardness score (EHS) as well as urinary statuses using the International Prostate Symptom Score (IPSS) and Overactive Bladder Symptom Score (OABSS) before and 3, 6, and 12 months after a daily treatment with 0.5?mg dutasteride (DUT). Significant improvements were observed in IPSS and OABSS in 98 patients with the DUT treatment, and the effects were similar between 28 patients with potency with baseline SHIM of 8 or greater and 70 severe erectile dysfunction (ED) patients at baseline. In the 28 patients with potency, significant decreases were observed in SHIM and EHS after 3, 6, and 12 months of the DUT treatment, with the severity of ED according to SHIM deteriorating in half of these patients after 12 months of the DUT treatment. Eighteen out of 28 patients (64.3%) with potency at baseline had awareness of the occurrence of ED before the DUT treatment, were younger, and had higher SHIM and EHS just before the DUT treatment than their counterparts. Regular assessments of EF may be needed, especially in younger patients and those with higher levels of EF before the administration of DUT.     

Sildenafil: two decades of benefits or risks?

Abstract

Sildenafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE-5). A patent was registered for this drug in 1990, which expired in 2010. Since expiration, the drug has been marketed under various trade names or as generic drugs. Numerous clinical trials have been conducted addressing the effectiveness of the drug for erectile dysfunction (ED) and its safety regarding the presence or absence of specific comorbidities. After over 20 years in the market, we need to ask: has the scientific community reached a general consensus as to the overall efficacy and safety of the drug? Can we firmly state that the benefits of the drug outweigh its risks? This review suggests that sildenafil is an effective and easily manageable treatment for erectile dysfunction, both in the absence and in the presence of comorbidities. After two decades of the emergence of sildenafil as a drug of choice for the treatment of ED (and the numerous studies and clinical trials undertaken during this time span), it is now possible to state that the benefits of the drug do outweigh the risks, and represent an significant improvement in the quality of life in men with ED.     

Epidemiology and risk factors of lower urinary tract symptoms/benign prostatic hyperplasia and erectile dysfunction

Benign prostatic hyperplasia (BPH) is very common in aging men and causes lower urinary tract symptoms (LUTS), which decrease health-related quality of life. A number of evidence suggests that other than ageing, modifiable factors, such as increasing prostate volume, obesity, diet, dyslipidemia, hormonal imbalance, hypertension, metabolic syndrome, alcohol, and smoking, also contribute to the development of BPH and/or LUTS. More recently, erectile dysfunction (ED) has been linked to LUTS/BPH as a part of this syndrome, suggesting that patients with BPH or LUTS easily develop ED, and that LUTS/BPH symptoms often coexist with ED. This article focuses on the epidemiology and risk factors of the combined phenotype LUTS/BPH – ED.     

Our common future: a rapidly growing and rapidly aging humankind

Abstract

Physical inactivity, diabetes, hypertension, dyslipidemia, smoking and obesity were associated with imbalance in oxidative stress, leading to endothelial dysfunction. Such dysfunction is present in both cardiovascular disease (CVD) and erectile dysfunction (ED). ED is the persistent inability to achieve or sustain an erection sufficient for satisfactory sexual performance and is one of the first manifestations of endothelial damage in men with CVD risk factors. The purpose of this article is to review the results of studies involving physical activity, CVD, endothelial dysfunction and ED in order to verify its applicability for improving the health and quality of life of men with such disorders. There is consistent evidence that endothelial damage is intimately linked to ED, and this manifestation seems to be associated with the appearance CVDs. On the other hand, physical activity has been pointed out as an important clinical strategy in the prevention and treatment of CVDs and ED mainly associated with improvement of endothelial function. However, further experimental and clinical prospective investigations are needed to test the role of physical exercises in the modulation of endothelial function and their implications on erectile function and the appearance of CVDs.     

Effects of testosterone replacement therapy withdrawal and re-treatment in hypogonadal elderly men upon obesity,voiding function and prostate safety parameters

Whether testosterone replacement therapy (TRT) is a lifelong treatment for men with hypogonadism remains unknown. We investigated long-term TRT and TRT withdrawal on obesity and prostate-related parameters. Two hundred and sixty-two hypogonadal patients (mean age 59.5) received testosterone undecanoate in 12-week intervals for a maximum of 11 years. One hundred and forty-seven men had TRT interrupted for a mean of 16.9 months and resumed thereafter (Group A). The remaining 115 patients were treated continuously (Group B). Prostate volume, prostate-specific antigen (PSA), residual voiding volume, bladder wall thickness, C-reactive protein (CRP), aging male symptoms (AMS), International Index of erectile function – erectile function (IIEF-EF) and International Prostate Symptoms Scores (IPSS) were measured over the study period with anthropometric parameters of obesity, including weight, body mass index (BMI) and waist circumference. Prior to interruption, TRT resulted in improvements in residual voiding volume, bladder wall thickness, CRP, AMS, IIEF-EF, IPSS and obesity parameters while PSA and prostate volume increased. TRT interruption reduced total testosterone to hypogonadal levels in Group A and resulted in worsening of obesity parameters, AMS, IPSS, residual voiding volume and bladder wall thickness, IIEF-EF and PSA while CRP and prostate volume were unchanged until treatment resumed whereby these effects were reversed. TRT interruption results in worsening of symptoms. Hypogonadism may require lifelong TRT.     

Object relations couple therapy for a married Korean man with sexual dysfunction

This study uses James Donovan's object relations couple therapy to examine the triangle of focus (conflict style, couple characteristics, and family of origin) and triangle of conflict (anxiety, defence mechanisms, and hidden emotions) of a married Korean man with sexual dysfunction (reduced sexual desire, premature ejaculation, and erectile dysfunction). This qualitative study uses thematic analysis to identify, describe, and analyse a family therapy case study. The aim of this study is to examine the couple's interaction patterns and experiences of conflicts related to the husband's erectile dysfunction. The researchers induced patterns or topics by repeatedly reading and comparing the data. Then, they textualised and analysed the relevant data. To ensure the reliability and validity of the data analysis, the researchers conducted shared coding sessions to review and discuss the initial codes and the generated main themes and subthemes, triangulating the qualitative data. Findings show that a newlywed husband's sexual dysfunction is associated with his emotional resistance towards his wife's unilateral pursuit over their sexual relationship and the negative emotions triggered by their dysfunctional interactions. Further, couple characteristics, conflict style (dysfunctional interactions), and family-of-origin factors (transference and patrilocality) influenced their sexual relationship. Therefore, therapists who counsel Korean couples with sexual issues may pay attention to the sociocultural factors, interactional patterns, and psychological factors associated with unresolved issues with their families of origin.     

Testosterone/estradiol ratio,is it useful in the diagnosis of erectile dysfunction and low sexual desire?

Erectile dysfunction and low sexual desire are multifactorial diseases. The decrease in testosterone levels is one of the causes, but the effect of estradiol is not well known. Moreover, study has shown that the testosterone/estradiol ratio has more influence over sexuality than does estradiol alone. The aim of the study was to determine whether the balance between testosterone and estradiol has any relation to some aspects of sexual function. It was an ambispective study of 230 patients with urological problems unrelated to sexuality. They underwent a detailed history and hormone study including total, free, bioavailable testosterone and estradiol. They completed the Sexual Health Inventory for Men and questions 11 and 12 of the IIEF15 were used to assess impairment in sexual desire. The T/E ratio was calculated, and the relationship between the different parameters and erectile function and sexual desire were studied by univariate and multivariate analysis. The mean age was 66.32?±?8.17 years. The percentage of patients with erectile dysfunction was 60.9% (7% severe, 14.3% moderate, 12.6% mild to moderate and 27% mild) and decreased sexual desire was 46.5%. Age, free and biodisponible testosteron were the only variables with a positive linear association with erectile dysfunction and decreased sexual desire. Age was the only independent variable for both, erectile dysfunction and sexual desire, in the multiple linear regression. There was no association between a testosterone/estradiol imbalance and an alteration in erectile function and sexual desire. Consequently, in the clinical study of these patients, it is not necessary to request estradiol in the laboratory analyses.     

Weapons of penile smooth muscle destruction: Androgen deficiency promotes accumulation of adipocytes in the corpus cavernosum

In men with erectile dysfunction, venous leakage is a common condition among non-responders to medical management and is attributed to penile smooth muscle atrophy. Androgens play a role in regulating trabecular smooth muscle growth and function. Further, androgens stimulate differentiation of progenitor cells into smooth muscle cells and inhibit their differentiation into adipocytes. We postulate that androgens exert a direct effect on penile tissue to maintain erectile function, and that androgen deficiency produces metabolic and structural imbalances in the corpus cavernosum, resulting in venous leakage and erectile dysfunction. To date, research efforts on the mechanisms by which androgens regulate penile erectile physiology have mainly focused on investigating the role of the NO/cGMP pathway. However, androgen-dependent mechanisms that regulate tissue remodeling have been poorly defined. Characterization of the molecular and cellular mechanisms by which androgens regulate corpus cavernosum structural and functional integrity would provide significant gains in knowledge and understanding of an important pathogenic process. In this review, we discuss the potential role of androgen in maintaining differentiation of progenitor cells into smooth muscle lineage and inhibition of differentiation into adipocytes. Androgen deficiency promotes differentiation into adipogenic lineage, and accumulation of adipocytes in the corpus cavernosum may contribute to erectile dysfunction.     

Clinical experience with the new long-acting injectable testosterone undecanoate. Report on the educational symposium on the occasion of the 5th World Congress on the Aging Male, 9–12 February 2006, Salzburg,Austria

This symposium report summarizes first extensive clinical findings with injectable testosterone undecanoate (Nebido®) in hypogonadal patients showing clinical symptoms of androgen deficiency with or without erectile dysfunction (ED). This new testosterone formulation (1000 mg testosterone undecanoate in 4 ml castor oil) possesses nearly ideal long-term kinetics, i.e. sustained close mimicking of eugonadal testosterone serum levels without supra- or sub-physiological serum concentrations. The generally accepted administration scheme recommends the second injection 6 weeks after the first one followed by further injections every 12 weeks. Applying this regimen, administration intervals are drastically reduced in comparison to conventional i.m. testosterone preparations (e.g. about 16 injections of testosterone enanthate vs. 4–5 injections of testosterone undecanoate per year). Depending on the testosterone serum levels, individualized therapy is possible by shortening (every 10 weeks) or prolonging (every 14 weeks) the injection intervals. In hypogonadal patients with ED 58% respond to testosterone undecanoate alone. Best results are seen in diabetic hypogonadal patients. The regimen of injectable testosterone undecanoate administration ideally fits recommendations regarding pharmacokinetics, efficacy and safety monitoring.