Testosterone replacement therapy: current trends and future directions

Current and future testosterone delivery systems for treatment of the hypogonadal male

BACKGROUND

Hypogonadism is manifest in all age groups, and a growing elderly population is requiring treatment for testosterone deficiency, presenting new safety challenges, as many of these individuals present with comorbidities and significant risk profiles.

OBJECTIVE

To discuss testosterone replacement modalities, their advantages and disadvantages, and provide a discussion of safety issues.

METHODS

We reviewed the literature regarding testosterone replacement therapy and have provided a summary of our most outstanding findings.

CONCLUSION

Potential benefits of testosterone replacement therapy include increased lean body mass, heightened libido, increased bone density and elevation of mood. Some disadvantages are clearly defined, while others require further investigation. Patient and physician must cooperate to agree on an individual patient's most appropriate and tolerable route of administration.

Androgen deficiency as a predictor of metabolic syndrome in aging men: an opportunity for intervention?

The prevalence of metabolic syndrome is increasing globally and is an important risk factor for the development of cardiovascular disease. Longitudinal population studies have found that low testosterone status in men is a risk factor for the later development of metabolic syndrome. Men with metabolic syndrome and type 2 diabetes mellitus have a higher incidence of hypotestosteronaemia. Furthermore, in men, testosterone levels are inversely associated with the degree of carotid and aortic atherosclerosis. Early interventional, short-term studies have shown that testosterone replacement therapy has a beneficial effect on visceral obesity, insulin sensitivity, glycaemic control and lipid profiles in men with diagnosed hypogonadism with and without diabetes. The effect of testosterone therapy on atherogenesis in men is unknown; however, animal studies have shown that testosterone is atheroprotective and can ameliorate the degree of atherosclerosis. Testosterone is an arterial vasodilator and has been shown to improve myocardial ischaemia in men with coronary artery disease. This review discusses the role that testosterone may play in the pathogenesis of metabolic syndrome in men and also examines the potential role of testosterone replacement therapy in this condition.

Persistence of androgenic effects on the production of proinflammatory cytokines by circulating antigen-presenting cells after withdrawal of testosterone treatment in aging type 2 diabetic men with partial androgen deficiency

OBJECTIVE

To test the hypothesis that T treatment withdrawal could be associated with an enhancement of proinflammatory cytokine production by peripheral blood monocytes and dendritic cells.

DESIGN

A prospective intervention study.

SETTING

Tertiary university hospital.

PATIENT(S)

Thirteen type 2 diabetic men aged >55 years with partial androgen deficiency and eight age-matched healthy men (controls).

INTERVENTION(S)

Analyses were performed before and 12 months after T replacement therapy and the results compared with those obtained for the same patients after a 3-month T withdrawal period.

MAIN OUTCOME MEASURE(S)

Distribution of circulating T, B, and natural killer lymphocytes, monocytes, and CD33(hi) myeloid, CD16+, and plasmacytoid dendritic cell subsets. Spontaneous and stimulated ex vivo production of inflammatory cytokines (interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha) by circulating monocytes and dendritic cells, which represent the most potent antigen-presenting cells.

RESULT(S)

The reduction or complete abrogation of spontaneous ex vivo production of proinflammatory cytokines by monocytes and dendritic cells observed after 12 months of T replacement therapy was maintained 3 months after T withdrawal.

CONCLUSION(S)

These are the first results showing that exogenous T treatment deprivation is not associated with an immunologic enhancement of proinflammatory cytokine production by antigen-presenting cells.

Comparison of a new long-acting testosterone undecanoate formulation vs testosterone enanthate for intramuscular androgen therapy in male hypogonadism

OBJECTIVE

To assess the efficacy and safety of a novel long-acting im testosterone undecanoate (TU) formulation in comparison with testosterone enanthate (TE).

SUBJECTS AND METHODS

An open-label, randomized, prospective clinical trial in 40 hypogonadal men (baseline serum testosterone levels <5 nmol/l), randomly assigned to 250 mg TE/3 weeks (no.=20) or 1000 mg TU im every 6 to 9 weeks for 30 weeks (no.=20). Subsequently, 32/40 men continued the study for another 114 weeks, now receiving TU 1000 mg/12 weeks.

RESULTS

TU and TE produced no statistically significant improvements in grip strength over the first 30 weeks, which only occurred after approximately 90 weeks when all subjects received TU. There were no changes in body mass index with TU and TE, neither in the follow-up period when all patients received TU. But ratios of waist to hip circumferences declined in the longer term. Total serum cholesterol, LDL cholesterol, and triglycerides declined over the first 30 weeks, while plasma HDL also declined. Plasma LDL decreased further under long-term TU therapy, while HDL then increased. Hemoglobin and hematocrit values significantly increased over the first 30 weeks in both treatment groups and then no further increase was observed. Levels did not exceed the upper limit of normal. In both treatment groups, serum prostate specific antigen levels rose slightly after 30 weeks, with no further increase over the first 12 months, remaining stable within the normal range. Plasma T before the following TU injection was above the lower limit of reference values. Four injections per year are adequate.

CONCLUSIONS

Administration of TU every 12 weeks is at least as safe and efficacious for treatment of hypogonadal men as TE, with a substantially lower frequency of administration. Follow-up over 114 weeks, when all subjects received TU, showed an excellent profile of efficacy and safety.

Testosterone for the aging male; current evidence and recommended practice

An international consensus document was recently published and provides guidance on the diagnosis, treatment and monitoring of late-onset hypogonadism (LOH) in men. The diagnosis of LOH requires biochemical and clinical components. Controversy in defining the clinical syndrome continues due to the high prevalence of hypogonadal symptoms in the aging male population and the non-specific nature of these symptoms. Further controversy surrounds setting a lower limit of normal testosterone, the limitations of the commonly available total testosterone result in assessing some patients and the unavailability of reliable measures of bioavailable or free testosterone for general clinical use. As with any clinical intervention testosterone treatment should be judged on a balance of risk versus benefit. The traditional benefits of testosterone on sexual function, mood, strength and quality of life remain the primary goals of treatment but possible beneficial effects on other parameters such as bone density, obesity, insulin resistance and angina are emerging and will be reviewed. Potential concerns regarding the effects of testosterone on prostate disease, aggression and polycythaemia will also be addressed. The options available for treatment have increased in recent years with the availability of a number of testosterone preparations which can reliably produce physiological serum concentrations.

Advances in male contraception

Despite significant advances in contraceptive options for women over the last 50 yr, world population continues to grow rapidly. Scientists and activists alike point to the devastating environmental impacts that population pressures have caused, including global warming from the developed world and hunger and disease in less developed areas. Moreover, almost half of all pregnancies are still unwanted or unplanned. Clearly, there is a need for expanded, reversible, contraceptive options. Multicultural surveys demonstrate the willingness of men to participate in contraception and their female partners to trust them to do so. Notwithstanding their paucity of options, male methods including vasectomy and condoms account for almost one third of contraceptive use in the United States and other countries. Recent international clinical research efforts have demonstrated high efficacy rates (90-95%) for hormonally based male contraceptives. Current barriers to expanded use include limited delivery methods and perceived regulatory obstacles, which stymie introduction to the marketplace. However, advances in oral and injectable androgen delivery are cause for optimism that these hurdles may be overcome. Nonhormonal methods, such as compounds that target sperm motility, are attractive in their theoretical promise of specificity for the reproductive tract. Gene and protein array technologies continue to identify potential targets for this approach. Such nonhormonal agents will likely reach clinical trials in the near future. Great strides have been made in understanding male reproductive physiology; the combined efforts of scientists, clinicians, industry and governmental funding agencies could make an effective, reversible, male contraceptive an option for family planning over the next decade.

Risk factors for post-treatment hypogonadism in testicular cancer patients

OBJECTIVES

Testicular germ-cell cancer (TGCC) patients are at risk of developing hypogonadism but no risk factors have yet been defined.

METHODS

Blood was collected from 143 TGCC patients (after orchidectomy, prior to further therapy (T0) and 6, 12, 24, 36 and 60 months (T6, T12, T24, T36 and T60) after therapy). Biological hypogonadism (BH) was defined as: serum testosterone below 10 nmol/l and/or LH >10 IU/l; odds ratios (ORs) for BH with BH at T0, age, stage of disease, testicular characteristics, and androgen receptor polymorphism as predictors were calculated as well as the OR for developing BH post-treatment (one to two cycles of adjuvant chemotherapy (ACT) versus three to four cycles of higher dose chemotherapy (HCT) versus adjuvant radiotherapy (RT)).

RESULTS

HCT increased the OR for BH at T6 (OR 22, 95% confidence interval (CI) 4.4-118) and T12 (OR 5.8, 95% CI 1.5-22). RT increased the OR at T6 (OR 10, 95% CI 2.1-47) and at T12 (OR 3.9, 95% CI 1.1-14). Microlithiasis predicted BH at T0 (OR 11, 95% CI 1.2-112), T12 (OR 3.9, 95% CI 1.1-13), T24 (OR 3.0, 95% CI 1.0-8.8), T36 (OR 5.4, 95% CI 1.7-17) and T60 (OR 4.4, 95% CI 1.2-16). BH at T0 was a risk for BH at T6 (OR 53, 95% CI 19-145), T12 (OR 125, 95% CI 37-430), T24 (OR 88, 95% CI 26-300) and T36 (OR 121, 95% CI 32-460).

CONCLUSIONS

It is clinically relevant that BH at T0 and testicular microlithiasis were predictive factors for post-treatment BH. HCT and RT gave temporary BH.

Testosterone replacement therapy

Hypgonadism has important adverse effects on the health and quality of life of affected men, but remains underdiagnosed in clinical practice. This article reviews the physiology, causes and diagnosis of hypogonadism and the potential benefits of treatment with testosterone replacement therapy.

The burden of testosterone deficiency syndrome in adult men: economic and quality-of-life impact

INTRODUCTION

Testosterone deficiency syndrome (TDS) causes a wide range of symptoms that can lead to significant morbidity. Preliminary evidence has also linked TDS with premature mortality and with a number of comorbid diseases including diabetes and metabolic syndrome. Such associations can lead to substantial economic and quality-of-life implications, the magnitude of which remains largely unknown.

AIM

To review the economic and quality-of-life consequences of a largely untreated condition and to consider the likely health economic benefits of testosterone treatment.

METHODS

A systematic review of four main areas: epidemiological evidence of the magnitude of TDS, estimates of cost of illness, impact on quality-of-life, and cost-effectiveness of testosterone treatment.

MAIN OUTCOME MEASURE

Review of peer-reviewed literature.

RESULTS

The lack of clear universally accepted diagnostic criteria and the uncertainty surrounding the link between TDS and some of its consequences complicate the estimation of the burden of illness of TDS. Consequences of TDS that potentially lead to increased economic burden include depression, sexual dysfunction, mild cognitive impairment, osteoporosis, cardiovascular disease, and mortality. However, although good evidence exists demonstrating an association between TDS and sexual dysfunction and cognitive impairment, evidence is less strong for depression, the incidence of fractures and mortality, and highly controversial for cardiovascular disease. The consequences that are likely to impact on patients' quality of life include sexual function, energy levels, body composition, mood, and cognitive function.

CONCLUSION

Understanding the burden is only the first step decision makers need to take to decide whether to allocate scarce resources to treat the condition. To make informed decisions on when and who to treat information is also needed on the cost-effectiveness of available treatments. Such data would highlight the benefits of treatment of TDS to physicians, patients, and to society as a whole.

Androgen receptor gene CAG repeat length and body mass index modulate the safety of long-term intramuscular testosterone undecanoate therapy in hypogonadal men

CONTEXT

A reliable form of androgen substitution therapy regarding kinetics, tolerance, and restoration of androgenicity is paramount in hypogonadal men. Intramuscular injection of the long-acting ester testosterone undecanoate (TU) offers a new modality.

OBJECTIVE

The objective of the study was to assess the safety of TU regarding metabolic and pharmacogenetic confounders.

DESIGN

This was a longitudinal one-arm open observation trial. A minimum of five individual assessments was a prerequisite. Putative modulators of safety parameters entering regression models were nadir and/or delta total testosterone concentrations, body mass index, androgen receptor (AR) gene CAG repeat length, and age.

SETTING

The study was conducted at an andrological outpatient clinic.

PATIENTS

Patients included 66 hypogonadal men (mean age 38 +/- 9.9 yr).

MAIN OUTCOME MEASURES

A total of 515 data time points each related to prostate, erythropoiesis, lipoproteins, and circulation during 118 treatment-years with 1000 mg TU at 10- to 14-wk intervals.

RESULTS

Testosterone substitution resulted in significant decrements of serum levels of low-density lipoprotein-cholesterol, resting diastolic and systolic blood pressure, and heart rate. Erythropoiesis was stimulated and concentrations of high-density lipoproteincholesterol increased. Parameters remained stable after four injections. No adverse effects regarding the prostate were observed. Significantly increased hematocrit greater than 50% was predicted by enhanced androgen action (shorter AR CAG repeats per higher testosterone levels). However, insufficient androgen action (longer AR CAG repeats per lower testosterone levels) caused pathological safety parameters (high blood pressure, adverse lipid profiles). In addition, a body mass index 30 kg/m(2) or greater represents a clinically relevant factor for the occurrence of all pathological safety parameters. Risk calculations for obese patients and nonlinear pharmacogenetic models to tailor androgen substitution are presented.

CONCLUSIONS

Testosterone substitution with im TU is generally well tolerated. Modifications of androgen action are due to both AR CAG repeats and testosterone levels. Adverse observations are mostly seen in obese patients.

Testosterone treatment to mimic hormone physiology in androgen replacement therapy. A view on testosterone gel and other preparations available

There is still considerable controversy concerning the issue of testosterone replacement therapy. This is because testosterone replacement therapy is not a 'risk-free' treatment and a randomized controlled trial to evaluate safety of prolonged testosterone replacement therapy is not available, nor is it likely to be in the near future. However, recent testosterone delivery systems, such as the 1% gel (Testogel, Androgel and Testim), have proven to have a good physiologic profile, allowing constant monitoring of the possible complications and prompt discontinuation in the event of adverse effects. The aim of this paper is to provide a comprehensive review of the available testosterone preparations to treat male hypogonadism, with special interest in the treatment of ageing men and late-onset hypogonadism. In addition, the experimental and clinical data on the effect of testosterone on sexual function domains is reviewed along with the indication for the combination therapy of androgens with pro-erectile drugs, for example, type 5 phosphodiesterase inhibitors.

Hypopituitarism

Incidence and prevalence of hypopituitarism are estimated to be 4.2 per 100,000 per year and 45.5 per 100,000, respectively. Although the clinical symptoms of this disorder are usually unspecific, it can cause life-threatening events and lead to increased mortality. Current research has refined the diagnosis of hypopituitarism. Identification of growth hormone and corticotropin deficiency generally requires a stimulation test, whereas other deficiencies can be detected by basal hormones in combination with clinical judgment. Newly developed formulations of replacement hormones are convenient and physiological. Work has shown that many patients with brain damage--such as traumatic brain injury or aneurysmal subarachnoid haemorrhage--are at high risk of (sometimes unrecognised) hypopituitarism. Thus, a much increased true prevalence of this disorder needs to be assumed. As a result, hypopituitarism is not a rare disease and should be recognised by the general practitioner.

Clinical and biochemical assessment of hypogonadism in men with type 2 diabetes: correlations with bioavailable testosterone and visceral adiposity

OBJECTIVE

The aim of our study was to assess the prevalence of clinical hypogonadism, based on both symptoms and biochemical available measures of testosterone deficiency, in men with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In a cross-sectional study of 355 type 2 diabetic men aged >30 years, total and bioavailable testosterone, sex hormone-binding globulin, BMI, and waist circumference were measured and free testosterone was calculated. Overt hypogonadism was defined as the presence of clinical symptoms of hypogonadism and low testosterone level (total testosterone <8 nmol/l and/or bioavailable testosterone <2.5 nmol/l). Borderline hypogonadism was defined as the presence of symptoms and total testosterone of 8-12 nmol/l or bioavailable testosterone of 2.5-4 nmol/l.

RESULTS

A low blood testosterone level was common in diabetic men, and a significant proportion of these men had symptoms of hypogonadism. Overt hypogonadism was seen in 17% of men with total testosterone <8 nmol/l and 14% with bioavailable testosterone <2.5 nmol/l. Borderline hypogonadism was found in 25% of men with total testosterone 8-12 nmol/l and bioavailable testosterone between 2.5 and 4 nmol/l; 42% of the men had free testosterone <0.255 nmol/l. BMI and waist circumference were both significantly negatively correlated with testosterone levels in men, with the association being stronger for waist circumference.

CONCLUSIONS

Testosterone levels are frequently low in men with type 2 diabetes, and the majority of these men have symptoms of hypogonadism. Obesity is associated with low testosterone levels in diabetic men.

Anterior pituitary hormone replacement therapy--a clinical review

This clinical review summarizes current approaches to diagnosis and treatment of anterior pituitary hormone deficiency. The diagnostic value of endocrine function tests and replacement strategies for hydrocortisone, thyroxine, sex steroids, and growth hormone replacement are reviewed. Female androgen deficiency syndrome and the current role of DHEA and testosterone replacement in women are also discussed.

Association of specific symptoms and metabolic risks with serum testosterone in older men

CONTEXT

Although attention and concern about health disorders in aging men have been growing, the structure of psychological and somatic complaints of actual patients, not population-based cohorts, has not been elucidated in relation to sex hormone patterns and metabolism.

OBJECTIVE

The objective of the study was investigation of factors influencing complaint structures in aging male patients.

DESIGN

This was a cross-sectional cohort study.

SETTING

The study was conducted in an andrological outpatient department.

PATIENTS

Subjects included 434 consecutive male patients aged 50-86 yr.

MAIN OUTCOME MEASURES

The following hypotheses were measured: 1) psychosomatic complaints and metabolic factors in aging male patients are related to sex hormone levels in a symptom-specific manner, and 2) patients form subcohorts.

RESULTS

A clear-cut threshold for late-onset hypogonadism was not found; rather, prevalence of psychosomatic symptoms and metabolic risk factors accumulated with decreasing androgen levels. For example, androgen-induced prevalence of loss of libido or vigor increased below testosterone concentrations of 15 nmol/liter (P < 0.001), whereas depression and diabetes mellitus type 2 (also in nonobese men) were significantly more present in men with testosterone concentrations below 10 nmol/liter (P < 0.001). Erectile dysfunction was identified as a composite pathology of metabolic risk factors, smoking, and depressivity, whereas only testosterone concentrations below 8 nmol/liter contributed to that symptom (P = 0.003). Cluster analysis revealed aging men to present within three independent groups characterized by psychosomatic complaints, metabolic disorders, and sexual health problems. These subgroups of patients exhibit distinct features in terms of androgen levels, age, and body mass index.

CONCLUSIONS

There is no evidence that a uniform structure of testosterone concentrations and complaints exists within the cohort of elderly male patients. Rather, in aging male patients, psychosomatic complaints and metabolic risk relate to testosterone in a symptom-specific manner.

Testosterone treatment comes of age: new options for hypogonadal men

Male hypogonadism is one of the most frequent, but also most underdiagnosed, endocrinopathies. However, the required testosterone treatment is simple and very effective if properly administered. Although testosterone has been available for clinical use for seven decades, until quite recently the treatment modalities were far from ideal. Subdermal testosterone pellets require minor surgery for insertion and often cause local problems. The injectable testosterone enanthate, for a long period the most frequently used mode of administration, lasts for two to four weeks, but produces supraphysiological levels initially and low levels before the next injection. The oral testosterone undecanoate has to be taken three times daily, has an uncertain absorption pattern and results in peaks and valleys of serum testosterone levels throughout the day. With the advent of transdermal testosterone preparations, the desired physiological serum levels could be achieved for the first time. Scrotal testosterone patches were the first to fulfil this requirement. These were followed by nonscrotal skin patches, which, however, cause considerable skin reactions including erythema and blisters. Recently introduced, invisible transdermal testosterone gels increased the intervals of application and are now slowly replacing other modalities. A mucoadhesive buccal testosterone tablet with sustained release is also a recent competing modality. Finally, injectable testosterone undecanoate in castor oil was made into a real depot preparation requiring only four injections per year for replacement therapy. These new preparations with a desired pharmacokinetic testosterone profile give the patient a real choice and make treatment easier. Based on pharmacogenetic considerations taking the androgen receptor polymorphism into account, treatment may be individualized for each patient in the future.

The testosterone mimetic properties of icariin

AIM

To evaluate the testosterone mimetic properties of icariin.

METHODS

Forty-eight healthy male Sprague-Dawley rats at the age of 15 months were randomly divided into four groups with 12 rats each: the control group (C), the model group (M), the icariin group (ICA) and the testosterone group (T). The reproductive system was damaged by cyclophosphamide (intraperitoneal injection, 20 mg/kg x day) for 5 consecutive days for groups M, ICA and T, at the sixth day, ICA (gastric gavage, 200 mg/kg x day) for the ICA group and sterandryl (subcutaneous injection, 5 mg/rat . day) for the T group for 7 consecutive days, respectively. The levels of serum testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH), serum bone Gla-protein (BGP) and tartrate-resistant acid phosphatase activity in serum (StrACP) were determined. The histological changes of the testis and the penis were observed by microscope with hematoxylin-eosin (HE) staining and terminal deoxynucleotidyl transferase biotin-dUTP-X nick end labeling (TUNEL), respectively.

RESULTS

(1) Icariin improved the condition of reproductive organs and increased the circulating levels of testosterone. (2) Icariin treatment also improved the steady-state serum BGP and might have promoted bone formation. At the same time, it decreased the serum levels of StrACP and might have reduced the bone resorption. (3) Icarrin suppressed the extent of apoptosis of penile cavernosal smooth muscle cells.

CONCLUSION

Icariin has testosterone mimetic properties and has therapeutic potential in the management of hypoandrogenism.

Testosterone replacement therapy in male hypogonadism is not associated with increase of endothelin-1 levels

Differences in endothelin-1 (ET-1) blood plasma levels were established between healthy men and women. Little is known about vascular effects of testosterone and the interactions between sex hormones and endothelin. In order to study the relationship between ET-1 and testosterone in more detail, we have investigated 33 male patients with various forms of hypogonadism (13 with hypergonadotropic hypogonadism and 20 with hypogonadotropic hypogonadism). Fourteen age-matched healthy males served as controls. The basal ET-1 levels in patients with hypogonadism (0.96 +/- 0.12 fmol/mL) (mean +/- SEM) were significantly higher in comparison with the controls (0.44 +/- 0.04 fmol/mL), p < 0.01. Fifteen individuals of these patients were studied during the therapy with testosterone depot 250 mg i.m. The ET-1 levels decreased in this group from 0.99 +/- 0.22 to 0.78 +/- 0.14 fmol/mL at the third and to 0.76 +/- 0.25 fmol/mL at the sixth month of the medication, respectively. The differences were not significant compared with the initial levels, but the concentrations at the sixth month of the treatment were not statistically different in comparison with the ET-1 levels of the controls. There was no significant difference in lipid data between patients before and during testosterone medication, except for the high-density lipoprotein cholesterol, which decreased at the third month of the treatment. Our results show that plasma ET-1 levels in males with hypogonadism are elevated with a tendency to decrease after testosterone administration. The optimum testosterone is not associated with enhanced cardiovascular risk as far as ET-1 plasma levels and lipids are concerned.

Testosterone replacement therapy for late-onset hypogonadism

Cross-sectional and longitudinal studies have shown that testosterone levels fall with increasing age. Low testosterone levels are reported in 20% of men aged 60-69 years, and 30% of men in this age-group are thought to have low free testosterone levels. The prevalence of low testosterone levels increases in older men and, therefore, as the average age of men in developed countries is increasing, there will be even more hypogonadal men in the future. Many of the symptoms and signs associated with testosterone deficiency in younger men are present in aging men. Several small studies suggest that testosterone replacement therapy (TRT) can be beneficial for some aging men, but men in these studies have not been uniformly testosterone-deficient, and responses have been inconsistent. TRT might be more beneficial and safer in men aged below 65 years than in men aged 65 years or older. There is a need for large clinical trials in both age-groups to provide more definitive information for patients and clinicians as to the safety and efficacy of TRT. Before such data are available, clinicians must be cautious in offering these treatments to aging men. Close monitoring of patients undergoing testosterone supplementation is essential.

Advances in male hormone substitution therapy

Increased awareness of the clinical diagnosis of male hypogonadism has resulted in the wider use of androgen substitution therapy. Clinical signs and symptoms together with a low serum testosterone level confirm the diagnosis of male hypogonadism. Androgen replacement results in improved sexual function, mood, muscle mass and bone density in most hypogonadal men. Such benefits must be assessed against potential risks. In older men, the potential risks of androgen treatment of hypogonadism are not known. Many delivery systems for androgen substitution are now available; the preparation chosen depends on the choice of the patient and his physician. Selective androgen receptor modulators offer tissue selective biological effects and the possibility of attaining maximum efficacy and minimum adverse effects.

Delivery options for contraceptives

Although a steady increase in contraceptive use has been observed in developed and less-developed countries, the contraceptive needs of a significant proportion of couples have not yet been met, resulting in an increase in unplanned pregnancies. Several new contraceptive products have reached the market during the past few years. Among these are new implants, a medicated intrauterine device, contraceptive vaginal rings, transdermal patches and several new regimen of combined oral contraceptives. These new or improved methods have been developed to expand the contraceptive choices available to women and men as well as to respond to the unmet need for contraceptives with long-term activity. New targets are being identified both in the ovary and the testes for a more specific non-hormonal contraception. This futuristic approach still keeps in mind the need for better access to existing contraceptive methods, as well as the discovery of new contraceptives that are simple to use, safe, reversible and inexpensive. In recent years, there has been great interest in agents that provide dual protection against pregnancy and sexually transmitted infections (STI), especially human immunodeficiency virus (HIV). A contraceptive method providing dual medical benefits might increase motivation for consistent use, thus reducing contraceptive failures and unwanted pregnancies.