Male Hormonal Contraception: Suppression of Spermatogenesis by Injectable Testosterone Undecanoate Alone or With Levonorgestrel Implants in Chinese Men

Practice and development of male contraception: European Academy of Andrology and American Society of Andrology guidelines

BACKGROUNDS

Despite a wide spectrum of contraceptive methods for women, the unintended pregnancy rate remains high (45% in the US), with 50% resulting in abortion. Currently, 20% of global contraceptive use is male-directed, with a wide variation among countries due to limited availability and lack of efficacy. Worldwide studies indicate that >50% of men would opt to use a reversible method, and 90% of women would rely on their partner to use a contraceptive. Additional reasons for novel male contraceptive methods to be available include the increased life expectancy, sharing the reproductive risks among partners, social issues, the lack of pharma industry involvement and the lack of opinion makers advocating for male contraception.

AIM

The present guidelines aim to review the status regarding male contraception, the current state of the art to support the clinical practice, recommend minimal requirements for new male contraceptive development and provide and grade updated, evidence-based recommendations from the European Society of Andrology (EAA) and the American Society of Andrology (ASA).

METHODS

An expert panel of academicians appointed by the EAA and the ASA generated a consensus guideline according to the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system.

RESULTS

Sixty evidence-based and graded recommendations were produced on couple-centered communication, behaviors, barrier methods, semen analysis and contraceptive efficacy, physical agents, surgical methods, actions before initiating male contraception, hormonal methods, non-hormonal methods, vaccines, and social and ethical considerations.

CONCLUSION

As gender roles transform and gender equity is established in relationships, the male contribution to family planning must be facilitated. Efficient and safe male-directed methods must be evaluated and introduced into clinical practice, preferably reversible, either hormonal or non-hormonal. From a future perspective, identifying new hormonal combinations, suitable testicular targets, and emerging vas occlusion methods will produce novel molecules and products for male contraception.

Initiating male contraception methods

Non-surgical (reversible) male contraception methods, when approved for general clinical application, should be made available to all interested men aged 18 50 years in good general health regardless of their semen parameters. In the preliminary workup, a complete personal and family history aimed at identifying specific conditions that may potentially increase the risks for adverse effects (associated with testosterone replacement) is advisable but a general or andrological examination is not required, unless indicated by the history. Baseline body weight, blood pressure and haemoglobin should be recorded for the purpose of future monitoring. While risks and benefits of vasectomy have been well established, appropriately nuanced patient counselling and assessment are essential for ensuring a satisfactory outcome of vasectomy.

The current state of male hormonal contraception

World population continues to grow at an unprecedented rate, doubling in a mere 50years to surpass the 7-billion milestone in 2011. This steep population growth exerts enormous pressure on the global environment. Despite the availability of numerous contraceptive choices for women, approximately half of all pregnancies are unintended and at least half of those are unwanted. Such statistics suggest that there is still a gap in contraceptive options for couples, particularly effective reversible contraceptives for men, who have few contraceptive choices. Male hormonal contraception has been an active area of research for almost 50years. The fundamental concept involves the use of exogenous hormones to suppress endogenous production of gonadotropins, testosterone, and downstream spermatogenesis. Testosterone-alone regimens are effective in many men but high dosing requirements and sub-optimal gonadotropin suppression in 10-30% of men limit their use. A number of novel combinations of testosterone and progestins have been shown to be more efficacious but still require further refinement in delivery systems and a clearer understanding of the potential short- and long-term side effects. Recently, synthetic androgens with both androgenic and progestogenic activity have been developed. These agents have the potential to be single-agent male hormonal contraceptives. Early studies of these compounds are encouraging and there is reason for optimism that these may provide safe, reversible, and reliable contraception for men in the near future.

Beyond the Condom: Frontiers in Male Contraception

Nearly half of all pregnancies worldwide are unplanned, despite numerous contraceptive options available. No new contraceptive method has been developed for men since the invention of condom. Nevertheless, more than 25% of contraception worldwide relies on male methods. Therefore, novel effective methods of male contraception are of interest. Herein we review the physiologic basis for both male hormonal and nonhormonal methods of contraception. We review the history of male hormonal contraception development, current hormonal agents in development, as well as the potential risks and benefits of male hormonal contraception options for men. Nonhormonal methods reviewed will include both pharmacological and mechanical approaches in development, with specific focus on methods which inhibit the testicular retinoic acid synthesis and action. Multiple hormonal and nonhormonal methods of male contraception are in the drug development pathway, with the hope that a reversible, reliable, safe method of male contraception will be available to couples in the not too distant future.

Male hormonal contraception: looking back and moving forward

Despite numerous contraceptive options available to women, approximately half of all pregnancies in the United States and worldwide are unplanned. Women and men support the development of reversible male contraception strategies, but none have been brought to market. Herein we review the physiologic basis for male hormonal contraception, the history of male hormonal contraception development, currents agents in development as well as the potential risks and benefits of male hormonal contraception for men.

Influence of testosterone gel treatment on spermatogenesis in men with hypogonadism

The prevalence of androgen deficiency in reproductive-aged men is increasing and needs new approach to long-term hypogonadism treatment that can preserve fertility. An open non-controlled pilot study included 18 men with eugonadotropic hypogonadism, who received transdermal testosterone gel treatment for 3 months. Sperm analysis was made before treatment and after 3 month of testosterone therapy. Testosterone level was normalized in all patients, but no negative effect was observed on spermatogenesis. Testosterone gel therapy may be a therapy of choice in hypogonadal men of reproductive age but further studies are needed.

Male contraception

Clear evidence shows that many men and women would welcome new male methods of contraception, but none have become available. The hormonal approach is based on suppression of gonadotropins and thus of testicular function and spermatogenesis, and has been investigated for several decades. This approach can achieve sufficient suppression of spermatogenesis for effective contraception in most men, but not all; the basis for these men responding insufficiently is unclear. Alternatively, the non-hormonal approach is based on identifying specific processes in sperm development, maturation and function. A range of targets has been identified in animal models, and targeted effectively. This approach, however, remains in the pre-clinical domain at present. There are, therefore, grounds for considering that safe, effective and reversible methods of contraception for men can be developed.

Reversible infertility associated with testosterone therapy for symptomatic hypogonadism in infertile couple

PURPOSE

Androgen replacement therapy has been shown to be safe and effective for most patients with testosterone deficiency. Male partners of infertile couples often report significantly poorer sexual activity and complain androgen deficiency symptoms. We report herein an adverse effect on fertility caused by misusage of androgen replacement therapy in infertile men with hypogonadal symptoms.

MATERIALS AND METHODS

The study population consisted of 8 male patients referred from a local clinic for azoospermia or severe oligozoospermia between January 2008 and July 2011. After detailed evaluation at our andrology clinic, all patients were diagnosed with iatrogenic hypogonadism associated with external androgen replacement. We evaluated changes in semen parameters and serum hormone level, and fertility status.

RESULTS

All patients had received multiple testosterone undecanoate (NebidoR) injections at local clinic due to androgen deficiency symptoms combined with lower serum testosterone level. The median duration of androgen replacement therapy prior to the development of azoospermia was 8 months (range: 4-12 months). After withdrawal of androgen therapy, sperm concentration and serum follicle-stimulating hormone level returned to normal range at a median 8.5 months (range: 7-10 months).

CONCLUSION

Misusage of external androgen replacement therapy in infertile men with poor sexual function can cause temporary spermatogenic dysfunction, thus aggravating infertility.

Steroid hormones for contraception in men

BACKGROUND

Male hormonal contraception has been an elusive goal. Administration of sex steroids to men can shut off sperm production through effects on the pituitary and hypothalamus. However, this approach also decreases production of testosterone, so 'add-back' therapy is needed.

OBJECTIVES

To summarize all randomized controlled trials (RCTs) of male hormonal contraception.

SEARCH METHODS

In January and February 2012, we searched the computerized databases CENTRAL, MEDLINE, POPLINE, and LILACS. We also searched for recent trials in ClinicalTrials.gov and ICTRP. Previous searches included EMBASE. We wrote to authors of identified trials to seek additional unpublished or published trials.

SELECTION CRITERIA

We included all RCTs that compared a steroid hormone with another contraceptive. We excluded non-steroidal male contraceptives, such as gossypol. We included both placebo and active-regimen control groups.

DATA COLLECTION AND ANALYSIS

The primary outcome measure was the absence of spermatozoa on semen examination, often called azoospermia. Data were insufficient to examine pregnancy rates and side effects.

MAIN RESULTS

We found 33 trials that met our inclusion criteria. The proportion of men who reportedly achieved azoospermia or had no detectable sperm varied widely. A few important differences emerged. 1) Levonorgestrel implants (160 μg daily) combined with injectable testosterone enanthate (TE) were more effective than levonorgestrel 125 µg daily combined with testosterone patches. 2) Levonorgestrel 500 μg daily improved the effectiveness of TE 100 mg injected weekly. 3) Levonorgestrel 250 μg daily improved the effectiveness of testosterone undecanoate (TU) 1000 mg injection plus TU 500 mg injected at 6 and 12 weeks. 4) Desogestrel 150 μg was less effective than desogestrel 300 μg (with testosterone pellets). 5) TU 500 mg was less likely to produce azoospermia than TU 1000 mg (with levonorgestrel implants). 6) Norethisterone enanthate 200 mg with TU 1000 mg led to more azoospermia when given every 8 weeks versus 12 weeks. 7) Four implants of 7-alpha-methyl-19-nortestosterone (MENT) were more effective than two MENT implants. We did not conduct any meta-analysis due to intervention differences.Several trials showed promising efficacy in percentages with azoospermia. Three examined desogestrel and testosterone preparations or etonogestrel and testosterone, and two examined levonorgestrel and testosterone.

AUTHORS' CONCLUSIONS

No male hormonal contraceptive is ready for clinical use. Most trials were small exploratory studies. Their power to detect important differences was limited and their results imprecise. In addition, assessment of azoospermia can vary by sensitivity of the method used. Future trials need more attention to the methodological requirements for RCTs. More trials with adequate power would also be helpful.

Simultaneous quantification of steroids in rat intratesticular fluid by HPLC-isotope dilution tandem mass spectrometry

An isotope dilution mass spectrometry method has been developed for the simultaneous measurement of picolinoyl derivatives of testosterone (T), dihydrotestosterone (DHT), 17β-estradiol (E(2)), and 5α-androstan-3α,17β-diol (3α-diol) in rat intratesticular fluid. The method uses reversed-phase high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. Following derivatization of 10-μL samples of testicular fluid with picolinoyl chloride hydrochloride, the samples were purified by solid phase extraction before analysis. The accuracy of the method was satisfactory for the 4 analytes at 3 concentrations, and both inter- and intraday reproducibility were satisfactory for T, DHT, and E(2). Measurements of intratesticular T concentrations in a group of 8 untreated adult rats by this method correlated well with measurements of the same samples by radioimmunoassay. As in men, there was considerable rat-to-rat variability in T concentration, despite the fact that the rats were inbred. Although its levels were more than an order of magnitude lower than those of T, DHT was measured reliably in all 8 intratesticular fluid samples. DHT concentration also varied from rat to rat and was highly correlated with T levels. The levels of E(2) and 3α-diol also were measurable. The availability of a sensitive method by which to measure steroids accurately and rapidly in the small volumes of intratesticular fluid obtainable from individual rats will make it possible to examine the effects, over time, of such perturbations as hormone and drug administration and environmental toxicant exposures on the intratesticular hormonal environment of exposed individual males and thereby to begin to understand differences in response between individuals.

Male hormonal contraception: potential risks and benefits

An effective, safe, reversible, and acceptable method of contraception is an important component of reproductive health and provides the opportunity of shared responsibility for family planning for both partners. Female hormonal contraceptives have been proven to be safe, reversible, available and widely acceptable by different populations. In contrast, male hormonal contraception, despite significant progress showing contraceptive efficacy comparable to female hormonal methods during last three decades, has not yet led to an approved product. Safety of a pharmaceutical product is an appropriate concern but the majority of male hormonal contraceptive clinical trials have not reported significant short term safety concerns. While the absence of serious adverse effects is encouraging, the studies have been designed for efficacy endpoints not long term safety. In this review we summarize potential risks and benefits of putative male hormonal contraceptives on reproductive and non-reproductive organs. While the review covers what we believe will be the likely class of drugs used for male hormonal contraception a true assessment of long term risks and benefits cannot be achieved without an available product.

Male hormonal contraception

The principle of hormonal male contraception based on suppression of gonadotropins and spermatogenesis has been established over the last three decades. All hormonal male contraceptives use testosterone, but only in East Asian men can testosterone alone suppress spermatogenesis to a level compatible with contraceptive protection. In Caucasians, additional agents are required of which progestins are favored. Current clinical trials concentrate on testosterone combined with norethisterone, desogestrel, etonogestrel, DMPA, or nestorone. The first randomized, placebo-controlled clinical trial performed by the pharmaceutical industry demonstrated the effectiveness of a combination of testosterone undecanoate and etonogestrel in suppressing spermatogenesis in volunteers.

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.

Progress and prospects in male hormonal contraception

PURPOSE OF REVIEW

Testosterone functions as a contraceptive by suppressing the secretion of luteinizing hormone and follicle-stimulating hormone from the pituitary. Low concentrations of these hormones deprive the testes of the signals required for spermatogenesis and results in markedly decreased sperm concentrations and effective contraception in a majority of men. Male hormonal contraception is well tolerated and acceptable to most men. Unfortunately, testosterone-alone regimens fail to completely suppress spermatogenesis in all men, meaning that in some the potential for fertility remains.

RECENT FINDINGS

Because of this, novel combinations of testosterone and progestins, which synergistically suppress gonadotropins, have been studied. Two recently published testosterone/progestin trials are particularly noteworthy. In the first, a long-acting injectable testosterone ester, testosterone decanoate, was combined with etonogestrel implants and resulted in 80-90% of subjects achieving a fewer than 1 million sperm per milliliter. In the second, a daily testosterone gel was combined with 3-monthly injections of depot medroxyprogesterone acetate producing similar results.

SUMMARY

Testosterone-based hormone combinations are able to reversibly suppress human spermatogenesis; however, a uniformly effective regimen has remained elusive. Nevertheless, improvements, such as the use of injectable testosterone undecanoate, may lead to a safe, reversible and effective male contraceptive.

Determinants of the rate and extent of spermatogenic suppression during hormonal male contraception: an integrated analysis

CONTEXT

Male hormonal contraceptive methods require effective suppression of sperm output.

OBJECTIVE

The objective of the study was to define the covariables that influence the rate and extent of suppression of spermatogenesis to a level shown in previous World Health Organization-sponsored studies to be sufficient for contraceptive purposes (< or =1 million/ml).

DESIGN

This was an integrated analysis of all published male hormonal contraceptive studies of at least 3 months' treatment duration.

SETTING

Deidentified individual subject data were provided by investigators of 30 studies published between 1990 and 2006.

PARTICIPANTS

A total of 1756 healthy men (by physical, blood, and semen exam) aged 18-51 yr of predominantly Caucasian (two thirds) or Asian (one third) descent were studied. This represents about 85% of all the published data.

INTERVENTION(S)

Men were treated with different preparations of testosterone, with or without various progestins.

MAIN OUTCOME MEASURE

Semen analysis was the main measure.

RESULTS

Progestin coadministration increased both the rate and extent of suppression. Caucasian men suppressed sperm output faster initially but ultimately to a less complete extent than did non-Caucasians. Younger age and lower initial blood testosterone or sperm concentration were also associated with faster suppression, but the independent effect sizes for age and baseline testicular function were relatively small.

CONCLUSION

Male hormonal contraceptives can be practically applied to a wide range of men but require coadministration of an androgen with a second agent (i.e. progestin) for earlier and more complete suppression of sperm output. Whereas considerable progress has been made toward defining clinically effective combinations, further optimization of androgen-progestin treatment regimens is still required.

More than eight years' hands-on experience with the novel long-acting parenteral testosterone undecanoate

Testosterone (T) as a compound for treatment of T deficiency has been available for almost 70 years, but the pharmaceutical formulations have been less than ideal. Traditionally, injectable T esters have been used for treatment, but they generate supranormal T levels shortly after the 2-3 weekly injection interval. T levels then decline very rapidly, becoming subnormal during the days preceding the next injection. The rapid fluctuations in plasma T are subjectively experienced as disagreeable. T undecanoate (TU) is a new injectable T preparation with a considerably better pharmacokinetic profile. After two initial injections separated by a 6-week interval, the following intervals between two injections are generally 12 weeks, eventually amounting to a total of four injections per year. Plasma T levels with this preparation are nearly always in the range of normal men, as are its metabolic products estradiol and dihydrotestosterone (DHT). It reverses the effects of hypogonadism on bone and muscle and metabolic parameters, and on sex functions. It is suitable for male contraception. Its safety profile is excellent because of the continuous normalcy of plasma T levels. No polycythemia has been observed and no adverse effects on lipid profiles. Prostate safety parameters are well within reference limits. TU is a valuable treatment option of androgen deficiency.

Steroid hormones for contraception in men

BACKGROUND

Male hormonal contraception has been an elusive goal. Administration of sex steroids to men can shut off sperm production through effects on the pituitary and hypothalamus. However, this approach also decreases production of testosterone, so 'add-back' therapy is needed.

OBJECTIVES

To summarize all randomized controlled trials of male hormonal contraception.

SEARCH STRATEGY

We searched the computerized databases CENTRAL, MEDLINE, EMBASE, POPLINE, and LILACS (each from inception to March 2006) for randomized controlled trials of hormonal contraception in men. We wrote to authors of identified trials to seek unpublished or published trials that we might have missed.

SELECTION CRITERIA

We included all randomized controlled trials in any language that compared a steroid hormone with another contraceptive. We excluded non-steroidal male contraceptives, such as gossypol. We included both placebo and active-regimen control groups. All trials identified included only healthy men with normal semen analyses.

DATA COLLECTION AND ANALYSIS

Azoospermia (absence of spermatozoa on semen examination) was the primary outcome measure. Data were insufficient to examine pregnancy rates and side effects.

MAIN RESULTS

We found 30 trials that met our inclusion criteria. The proportion of men who achieved azoospermia varied widely in reports to date. A few important differences emerged from these trials: levonorgestrel implants combined with injectable testosterone enanthate (TE) were more effective than levonorgestrel 125 microg daily combined with testosterone patches; levonorgestrel 500 mug daily improved the effectiveness of TE 100 mg injected weekly; desogestrel 150 mug was less effective than desogestrel 300 mug (with testosterone pellets); testosterone undecanoate (TU) 500 mg was less likely to produce azoospermia than TU 1000 mg (with levonorgestrel implants); norethisterone enanthate 200 mg with TU 1000 mg led to more azoospermia when given every 8 weeks versus 12 weeks; four implants of 7-alpha-methyl-19-nortestosterone (MENT) were more effective than two MENT implants. Several trials showed promising efficacy in terms of percentages with azoospermia. Three examined desogestrel and testosterone preparations or etonogestrel (metabolite of desogestrel) and testosterone, and two examined levonorgestrel and testosterone.

AUTHORS' CONCLUSIONS

No male hormonal contraceptive is ready for clinical use. Most trials were small exploratory studies. As a result, their power to detect important differences was limited and their results imprecise. In addition, the definition of oligozoospermia has been imprecise or inconsistent. To avoid bias, future trials need more attention to the methodological requirements for randomized controlled trials. More trials with adequate power would also be helpful.

The relative roles of follicle-stimulating hormone and luteinizing hormone in maintaining spermatogonial maturation and spermiation in normal men

CONTEXT

Male hormonal contraception via gonadotropin and intratesticular androgen withdrawal disrupts spermatogenesis at two principal sites: 1) spermatogonial maturation, and 2) spermiation.

OBJECTIVE

The objective of this study was to explore the relative dependence of each stage of germ cell development on FSH and LH/intratesticular androgen action.

DESIGN, SETTING, AND PARTICIPANTS

Eighteen men enrolled in this prospective, randomized 14-wk study at Prince Henry's Institute.

INTERVENTIONS

Subjects (n = 6/group) were assigned to 6 wk of 1) testosterone (T) implant (4 x 200 mg sc once)+depot medroxy progesterone acetate (DMPA; 150 mg im once); 2) T implant+DMPA+FSH (300 IU sc twice weekly); and 3) T implant+DMPA+human chorionic gonadotropin (hCG; 1000 IU sc twice weekly as an LH substitute). Men then underwent a vasectomy and testicular biopsy with previously reported control data used for comparison.

MAIN OUTCOME MEASURES

Germ cell number (assessed by the optical disector stereological approach) and intratesticular androgen levels were determined.

RESULTS

T+DMPA alone significantly suppressed type B spermatogonia, preleptotene through to pachytene spermatocytes, and round spermatids from control (P < 0.05). All germ cell subtypes were maintained at control levels by either FSH or LH activity, except pachytene spermatocytes, which were found to be lower in the hCG vs. FSH (P < 0.01) and control groups (P < 0.05).

CONCLUSIONS

FSH and LH maintained spermatogenesis independently in this gonadotropin-suppressed model. Compared with LH, FSH showed better maintenance of pachytene spermatocyte number, whereas improved conversion to round spermatids was suggested with hCG treatment. Future contraceptive treatment strategies must consider independent regulation of spermatogenesis by both FSH and LH/intratesticular androgens for maximum efficacy.

The many faces of progesterone: a role in adult and developing male brain

In addition to its well documented action in female-typical behaviors, progesterone exerts an influence on the brain and behavior of males. This review will discuss the role of progesterone and its receptor in male-typical reproductive behaviors in adulthood and the role of progesterone and its receptor in neural development, in both sexual differentiation of the brain as well as in the development of "non-reproductive" functions. The seemingly inconsistent and contradictory results on progesterone in males that exist in the literature illustrate the complexity of progesterone's actions and illuminate the need for further research in this area. As progestin-containing contraceptives in men are currently being tested and progesterone administration to pregnant women and premature newborns increases, a better understanding of the role of this hormone in behavior and brain development becomes essential.

Advances in male hormonal contraception

There is a need to develop new contraceptives, particularly for men whose current choices are suboptimal in terms of effectiveness and ease of reversibility. Recent surveys indicate that men and their partners would be willing to rely on male hormonal contraceptives. Male hormonal contraception works by reversibly suppressing sperm production. Testosterone in combination with progestins or gonadotropin-releasing hormone antagonists induces profound and consistent sperm suppression. Asian men are more susceptible to the suppressive effects of testosterone given alone, even if they may benefit from the addition of an adjunctive agent to obtain optimal contraceptive protection. The aim of this review is to comment on the recent relevant achievements in the field.

Rate, extent, and modifiers of spermatogenic recovery after hormonal male contraception: an integrated analysis

BACKGROUND

Hormonal methods for safe, reliable, and reversible contraception based on the suppression of spermatogenesis could soon become available. We have investigated the rate, extent, and predictors of reversibility of hormonal male contraception.

METHODS

We undertook an integrated multivariate time-to-event analysis of data from individual participants in 30 studies published in 1990-2005, in which sperm output was monitored every month until recovery. The primary outcome was the time for the sperm concentration to recover to a threshold of 20 million per mL, an indicator of fertility. We undertook univariate and multivariate analyses, using Kaplan-Meier and Cox's methods.

FINDINGS

1549 healthy eugonadal men who were white (n=965), Asian (almost all Chinese men; n=535), or of other origins (n=49) and aged 18-51 years underwent 1283.5 man-years of treatment and 705 man-years of post-treatment recovery. These data represented about 90% of all published data from individuals using androgen or androgen-progestagen regimens. The median times for sperm to recover to thresholds of 20, 10, and 3 million per mL were 3.4 months (95% CI 3.2-3.5), 3.0 months (2.9-3.1), and 2.5 months (2.4-2.7), respectively. Multivariate Cox's analysis showed higher rates of recovery with older age, Asian origin, shorter treatment duration, shorter-acting testosterone preparations, higher sperm concentrations at baseline, faster suppression of spermatogenesis, and lower blood concentrations of luteinising hormone at baseline. The typical probability of recovery to 20 million per mL was 67% (61-72) within 6 months, 90% (85-93) within 12 months, 96% (92-98) within 16 months, and 100% within 24 months.

INTERPRETATION

Hormonal male contraceptive regimens show full reversibility within a predictable time course. Various covariables affect the rate but not the extent of recovery, although their effect sizes are minor. These data are crucial for the further safe and practical development of such regimens.

Practical approaches to the diagnosis and management of male infertility

Male infertility affects 10% of couples of reproductive age worldwide, and is treatable in many cases. In addition to well-established etiologies, genetic causes of male infertility are now diagnosed more commonly, as our knowledge of genomic medicine advances. Using principles of evidence-based medicine, this review outlines diagnostic and treatment algorithms that guide clinical management. In order of importance, randomized controlled clinical trials, basic scientific studies, meta-analyses, case-controlled cohort studies, best-practice policy recommendations and reviews from peer-reviewed literature were incorporated into algorithms that provide organized and timely guidelines to the current management of male infertility. The strength of the evidence for treatment recommendations is also classified when appropriate.

Levonorgestrel implants enhanced the suppression of spermatogenesis by testosterone implants: comparison between Chinese and non-Chinese men

CONTEXT

Previous male contraceptive studies showed that progestins enhance spermatogenesis suppression by androgens in men.

OBJECTIVE

We compared the efficacy of spermatogenesis suppression by the combination of levonorgestrel (LNG) with testosterone (T) implants to that by T implants alone in two different ethnic groups.

DESIGN

This was a randomized trial performed in two centers with two treatment groups.

SETTINGS

The study was performed at the Academic Medical Center in the United States and the Research Institute in China.

PARTICIPANTS

Forty non-Chinese and 40 Chinese healthy male volunteers were studied.

INTERVENTIONS

Subjects were randomized to receive four LNG implants together with four T implants (inserted on d 1 and wk 15-18) vs. T implants alone for 30 wk.

MAIN OUTCOME MEASURES

The primary end point compared the efficiency of suppression to severe oligozoospermia (1 x 10(6)/ml) by LNG plus T implants vs. that by T implants alone. The secondary end point examined differences in spermatogenesis suppression between Chinese and non-Chinese subjects.

RESULTS

LNG plus T implants caused more suppression of spermatogenesis to severe oligozoospermia during the treatment period than T implants alone at both sites (P < 0.02). In Chinese men, severe oligozoospermia was achieved in more than 90% of the men in both treatment groups. Suppression to severe oligozoospermia was less in the non-Chinese men (59%) after T alone (P < 0.020); this difference disappeared with combined treatment (89%). T implant extrusion occurred in six men. Acne and increased hemoglobin were the most common adverse events.

CONCLUSION

T implants resulted in more pronounced spermatogenesis suppression in Chinese men. Addition of LNG implants to T implants enhanced the suppression of spermatogenesis in the treatment period in both Chinese and non-Chinese men.

Drug Insight: recent advances in male hormonal contraception

As there are limitations to current methods of male contraception, research has been undertaken to develop hormonal contraceptives for men, analogous to the methods for women based on estrogen and progestogens. When testosterone is administered to a man, it functions as a contraceptive by suppressing the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. Since these hormones are the main stimulatory signals for spermatogenesis, low levels of LH and FSH markedly impair sperm production. After 3-4 months of testosterone treatment, 60-70% of men no longer have sperm in their ejaculate, and most other men exhibit markedly diminished sperm counts. Male hormonal contraception is well tolerated, free of serious adverse side effects, and 95% effective in the prevention of pregnancy. Importantly, male hormonal contraception is reversible, with sperm counts usually recovering within 4 months of the discontinuation of hormone treatment. Because exogenous testosterone administration alone does not completely suppress sperm production in all men, researchers have combined testosterone with second agents, such as progestogens or gonadotropin-releasing-hormone antagonists, to further suppress secretion of LH and FSH and improve suppression of spermatogenesis. Recent trials have used combinations of long-acting injectable or implantable forms of testosterone with progestogens, which can be administered orally, by injection or by a long-acting implant. Such combinations suppress spermatogenesis to zero without severe side effects in 80-90% of men, with near-complete suppression in the remainder of individuals. One of these testosterone and progestogen combination regimens might soon bring the promise of male hormonal contraception to fruition.

Analysis of the Human Sperm Proteome

As part of our effort to identify putative protein targets for the development of male contraceptives, we performed an in-depth proteomic analysis of human sperm by liquid chromatography and tandem mass spectrometry. Motile sperm were collected from a single fertile individual and fractionated into detergent-soluble and detergent-insoluble fractions. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis separation of these fractions, followed by manual cutting of the gel, yielded 35 gel sections for each fraction to include proteins across the full range of electrophoretic mobility. Proteomic analysis of these gel sections identified more than 1,760 proteins with high confidence, with 1,350 proteins identified in the soluble fraction, 719 identified in the insoluble fraction, and 309 identified in both fractions. This characterization of the human sperm proteome provides a high-resolution, physiologically relevant index of the proteins that comprise human sperm.

Male Hormonal Contraceptives

Because of the shortcomings of currently available methods of male contraception, efforts have been made to develop additional forms of contraception for men. The most promising approach to male contraceptive development involves hormones, and requires the administration of exogenous testosterone. When administered to a healthy man, testosterone functions as a contraceptive by suppressing the secretion of luteinizing hormone and follicle-stimulating hormone from the pituitary, thereby depriving the testes of the signals required for normal spermatogenesis. After 2-3 months of treatment, low levels of pituitary gonadotropins lead to markedly decreased sperm counts and effective contraception in the majority of men. Treatment with exogenous testosterone has proven not to be associated with serious adverse effects and is well tolerated by men. In addition, sperm counts uniformly normalize when testosterone is discontinued. Thus, male hormonal contraception is safe, effective, and reversible; however, spermatogenesis is not suppressed to zero in all men, meaning that some diminished potential for fertility persists. Because of this, recent studies have combined testosterone with progestogens and/or gonadotropin-releasing hormone antagonists to further suppress pituitary gonadotropins and optimize contraceptive efficacy. Current combinations of testosterone and progestogens completely suppress spermatogenesis in 80-90% of men without severe adverse effects, with significant suppression in the remainder of individuals. Recent trials with newer, long-acting forms of injectable testosterone, which can be administered every 8 weeks, combined with progestogens, administered either orally or by long-acting implant, have yielded promising results and may soon result in the marketing of a safe, reversible, and effective hormonal contraceptive for men.