Hormonal approaches to male contraception: approaching reality

Male contraception: history and development

Although the twentieth century has seen great strides in the development of female contraception, not a single new agent has been introduced as an approved method for common use for male contraception. Condoms (considered uncomfortable by some) and vasectomy (a permanent invasive procedure) are the only options provided to men, leaving an undue burden on women to bear contraceptive responsibility. Significant developments have, however, been made with regard to hormonal and nonhormonal contraception, and minor, reversible, procedural contraception. This article reviews the currently available, soon to be available, and theoretically possible methods of male contraception.

Demand for male contraception

The biological basis for male contraception was established decades ago, but despite promising breakthroughs and the financial burden men increasingly bear due to better enforcement of child support policies, no viable alternative to the condom has been brought to market. Men who wish to control their fertility must rely on female compliance with contraceptives, barrier methods, vasectomy or abstinence. Over the last 10 years, the pharmaceutical industry has abandoned most of its investment in the field, leaving only nonprofit organisations and public entities pursuing male contraception. Leading explanations are uncertain forecasts of market demand pitted against the need for critical investments to demonstrate the safety of existing candidate products. This paper explores the developments and challenges in male contraception research. We produce preliminary estimates of potential market size for a safe and effective male contraceptive based on available data to estimate the potential market for a novel male method.

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.

Complete sperm suppression in rats with dienogest plus testosterone undecanoate is facilitated through apoptosis in testicular cells

Complete suppression of the production of sperm in rats with dienogest (DNG, 40 mg/kg body weight [bw]) plus testosterone undecanoate (TU, 25 mg/kg bw), every 45 days, was found to be associated with a significant increase in germ cell apoptosis. Caspase 3 activity and expression in testis were simultaneously upregulated. Rise in the activities of caspase 8 and 9 was associated with overexpression of upstream marker proteins from extrinsic (Fas [Fatty acid synthase], FasL [Fatty acid synthase ligand], and caspase 8) and intrinsic (Bax [Bcl2-associated-x protein], Bcl2 [B-cell lymphoma 2], and caspase 9) pathways of apoptosis. Apart from the germ cells, interstitial cell apoptosis was also observed along with a decline in the number of functional Leydig cells. It is therefore concluded that complete suppression of the production of sperm with DNG + TU is facilitated mainly through the removal of precursor germ cells through apoptosis. The process is largely modulated by upregulation of upstream and downstream marker proteins from intrinsic as well as extrinsic pathway of metazoan apoptosis.

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.

Testicular cell junction: a novel target for male contraception

Even though various contraceptive methods are widely available, the number of unwanted pregnancies is still on the rise in developing countries, pressurizing the already resource limited nations. One of the major underlying reasons is the lack of effective, low cost, and safe contraceptives for couples. During the past decade, some studies were performed using animal models to decipher if the Sertoli-germ cell junction in the testis is a target for male fertility regulation. Some of these study models were based on the use of hormones and/or chemicals to disrupt the hypothalamic-pituitary-testicular axis (e.g., androgen-based implants or pills) and others utilized a panel of chemical entities or synthetic peptides to perturb spermatogenesis either reversibly or non-reversibly. Among them, adjudin, a potential male contraceptive, is one of the compounds exerting its action on the unique adherens junctions, known as ectoplasmic specializations, in the testis. Since the testis is equipped with inter-connected cell junctions, an initial targeting of one junction type may affect the others and these accumulative effects could lead to spermatogenic arrest. This review attempts to cover an innovative theme on how male infertility can be achieved by inducing junction instability and defects in the testis, opening a new window of research for male contraceptive development. While it will still take much time and effort of intensive investigation before a product can reach the consumable market, these findings have provided hope for better family planning involving men.

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.

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.