Establishing the minimum effective dose and additive effects of depot progestin in suppression of human spermatogenesis by a testosterone depot

Male contraception: narrative review of ongoing research

BACKGROUND

Since the release of the combined oral contraceptive pill in 1960, women have shouldered the burden of contraception and family planning. Over 60 years later, this is still the case as the only practical, effective contraceptive options available to men are condoms and vasectomy. However, there are now a variety of promising hormonal and non-hormonal male contraceptive options being studied. The purpose of this narrative review is to provide clinicians and laypeople with focused, up-to-date descriptions of novel strategies and targets for male contraception. We include a cautiously optimistic discussion of benefits and potential drawbacks, highlighting several methods in preclinical and clinical stages of development.

RESULTS

As of June 2023, two hormonal male contraceptive methods are undergoing phase II clinical trials for safety and efficacy. A large-scale, international phase IIb trial investigating efficacy of transdermal segesterone acetate (Nestorone) plus testosterone gel has enrolled over 460 couples with completion estimated for late 2024. A second hormonal method, dimethandrolone undecanoate, is in two clinical trials focusing on safety, pharmacodynamics, suppression of spermatogenesis and hormones; the first of these two is estimated for completion in December 2024. There are also several non-hormonal methods with strong potential in preclinical stages of development.

CONCLUSIONS

There exist several hurdles to novel male contraception. Therapeutic development takes decades of time, meticulous work, and financial investment, but with so many strong candidates it is our hope that there will soon be several safe, effective, and reversible contraceptive options available to male patients.

Factors Associated With Restarting Androgenic Anabolic Steroids After Cessation in Men With Infertility: A Retrospective Analysis

Introduction The use of androgenic anabolic steroids (AAS) negatively affects male fertility by disrupting hormone release and reducing testosterone levels. Despite this, many men using steroids are unaware of fertility-related consequences. We aimed to determine the factors associated with AAS resumption during fertility treatment, specifically focusing on the duration, age, and dosage of AAS use prior to treatment. Our study, the first of its kind, investigated risk factors for resuming AAS following fertility assessment. Methods We conducted a retrospective review of adult men diagnosed with infertility due to chronic AAS use between 2012 and 2022 at the University of Miami. The study included men with azoospermia or severe oligospermia who were instructed to stop using AAS. Excluded were those who underwent orchiectomy for benign or malignant conditions. We collected data on demographic characteristics, AAS route details, fertility treatments, and AAS resumption. We hypothesized that risk factors for restarting AAS would include duration of AAS use, type of AAS, pre-treatment testosterone levels, and increased age. Results We identified 94 men with infertility caused by AAS use. Among them, 31 (33.0%) resumed AAS therapy within eight months after cessation. The median age of men who restarted AAS was 40 years. Those who resumed AAS had used it for a longer duration prior to fertility assessment compared to those who did not (60 months vs. 17 months, respectively). However, we found no statistically significant differences in age, duration of AAS use, AAS administration details, or serum testosterone levels at the time of initial assessment. Conclusion In conclusion, most men seeking fertility assessment due to AAS abuse did not resume testosterone therapy. However, those who did restart AAS had a longer history of AAS use. Future high-quality prospective studies are needed to better understand the risk factors associated with resuming AAS in male infertility caused by anabolic steroids.

Hormonal, chemical and thermal inhibition of spermatogenesis: contribution of French teams to international data with the aim of developing male contraception in France

Since the 1970s, international research on male contraception has been actively pursued. Hormonal and non-hormonal methods (thermal, chemical) have been tested, leading to clinical trials of interest to thousands of men and couples. The results showed that it was possible to develop methods of male contraception that inhibited spermatogenesis with good contraceptive efficacy. However, their side effects (mainly loss of libido), poorly accepted modes of administration, and the high frequency of poor responders prevented their widespread use. Based on earlier initiatives, new avenues were explored and significant progress was achieved, allowing the reasoned use of male contraception. For 40 years, several French teams have played an important role in this research. The aim of this paper is to outline the history and the progress of the experimental and clinical works of these teams who addressed hormonal, chemical and thermal approaches to male contraception. These approaches have led to a better comprehension of spermatogenesis that could be useful in fields other than male contraception: effects of toxic compounds, fertility preservation.

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.

A new combination of testosterone and nestorone transdermal gels for male hormonal contraception

CONTEXT

Combinations of testosterone (T) and nestorone (NES; a nonandrogenic progestin) transdermal gels may suppress spermatogenesis and prove appealing to men for contraception.

OBJECTIVE

The objective of the study was to determine the effectiveness of T gel alone or combined with NES gel in suppressing spermatogenesis.

DESIGN AND SETTING

This was a randomized, double-blind, comparator clinical trial conducted at two academic medical centers.

PARTICIPANTS

Ninety-nine healthy male volunteers participated in the study.

INTERVENTIONS

Volunteers were randomized to one of three treatment groups applying daily transdermal gels (group 1: T gel 10 g+NES 0 mg/placebo gel; group 2: T gel 10 g+NES gel 8 mg; group 3: T gel 10 g+NES gel 12 mg).

MAIN OUTCOME VARIABLE

The main outcome variable of the study was the percentage of men whose sperm concentration was suppressed to 1 million/ml or less by 20-24 wk of treatment.

RESULTS

Efficacy data analyses were performed on 56 subjects who adhered to the protocol and completed at least 20 wk of treatment. The percentage of men whose sperm concentration was 1 million/ml or less was significantly higher for T+NES 8 mg (89%, P<0.0001) and T+NES 12 mg (88%, P=0.0002) compared with T+NES 0 mg group (23%). The median serum total and free T concentrations in all groups were maintained within the adult male range throughout the treatment period. Adverse effects were minimal in all groups.

CONCLUSION

A combination of daily NES+T gels suppressed sperm concentration to 1 million/ml or less in 88.5% of men, with minimal adverse effects, and may be further studied as a male transdermal hormonal contraceptive.

Hormonal approaches to male contraception

PURPOSE OF REVIEW

Condoms and vasectomy are male-controlled family planning methods but suffer from limitations in compliance (condoms) and limited reversibility (vasectomy); thus many couples desire other options. Hormonal male contraceptive methods have undergone extensive clinical trials in healthy men and shown to be efficacious, reversible and appear to be well tolerated.

RECENT FINDINGS

The success rate of male hormonal contraception using injectable testosterone alone is high and comparable to methods for women. Addition of progestins to androgens improved the rate of suppression of spermatogenesis. Supported by government or nongovernment organizations, current studies aim to find the best combination of testosterone and progestins for effective spermatogenesis suppression and to explore other delivery methods for these hormones. Translation of these advances to widespread use in the developed world will need the manufacturing and marketing skills of the pharmaceutical industry. Availability of male contraceptives to the developing world may require commitments of governmental and nongovernmental agencies. In a time when imbalance of basic resources and population needs are obvious, this may prove to be a very wise investment.

SUMMARY

Male hormonal contraception is efficacious, reversible and well tolerated for the target population of younger men in stable relationships. Suppression of spermatogenesis is achieved with a combination of an androgen and a progestin. Partnership with industry will accelerate the marketing of a male hormonal contraceptive. Research is ongoing on selective androgen and progesterone receptor modulators that suppress spermatogenesis, minimize potential adverse events while retaining the androgenic and gonadotropin suppressive actions.

Combined transdermal testosterone gel and the progestin nestorone suppresses serum gonadotropins in men

CONTEXT

Testosterone (T) plus progestin combinations are the most promising hormonal male contraceptives. Nestorone (NES), a progestin without estrogenic or androgenic activity, when combined with T may be an excellent candidate for male contraception.

OBJECTIVE

Our objective was to determine the effect of transdermal NES gel alone or with T gel on gonadotropin suppression.

DESIGN AND SETTING

The randomized, unblinded clinical trial was conducted at two academic medical centers.

PARTICIPANTS

A total of 140 healthy male volunteers participated.

INTERVENTIONS

One hundred subjects were randomized initially (20 per group) to apply NES gel 2 or 4 mg, T gel 10 g, or T gel 10 g plus NES gel 2 or 4 mg daily for 20 d. Because only about half of the subjects in T plus NES 4 mg group suppressed serum gonadotropins to 0.5 IU/liter or less (suboptimal suppression), two additional groups of 20 men were randomized to apply daily T gel 10 g plus NES gel 6 or 8 mg.

MAIN OUTCOME VARIABLE

Suppression of serum LH and FSH concentrations to 0.5 IU/liter or less after treatment was the main outcome variable.

RESULTS

A total of 119 subjects were compliant with gel applications with few study-related adverse events. NES alone reduced gonadotropins significantly but less than T gel alone. Combined T gel 10g plus NES gel 6 or 8 mg suppressed both serum gonadotropins to 0.5 IU/liter or less in significantly more men than either gel alone.

CONCLUSION

Transdermal NES gel alone had gonadotropin suppression activity. Combined transdermal NES (6 or 8 mg) plus T gel demonstrated safe and effective suppression of gonadotropins, justifying a longer-term study of this combination for suppression of spermatogenesis.

Exploring older adolescents' and young adults' attitudes regarding male hormonal contraception: applications for clinical practice

BACKGROUND

Male hormonal contraceptive methods (HCM) are in Phase I clinical trials in the USA. International studies report that adults have positive attitudes regarding male HCM, but little is known about US minority young peoples' attitudes--a population that experiences high unintended pregnancy rates.

METHODS

Thirty urban African American young persons [50% males; mean age = 18.8 (SD = 2.5)] participated in semi-structured interviews to explore attitudes regarding male HCM. Data were independently analysed by two researchers according to qualitative research methodology, including transcript coding for content, categorization of codes, performance of content analysis for theme development, and corroboration of findings by a third researcher.

RESULTS

The data revealed five major themes that can facilitate and/or hinder male HCM adoption: (1) impact of reversing roles in HCM use; (2) men's lack of involvement in health care; (3) men's reliability to use HCM effectively; (4) perceived responsibility of men who use HCM; and (5) men's apprehension to use new medicines. Overall, participants had positive impressions about male HCM (67% male; 67% female) and female partner trust of males' use was high (85%), as were males' intentions (60%).

CONCLUSIONS

Findings provide a foundation for clinical interventions including: (1) increasing males' involvement in reproductive health; (2) helping males to overcome apprehensions about male HCM safety; and (3) standardizing male HCM education in the clinical setting. Future research efforts should examine whether study findings hold for other populations.

Dose-finding study of oral desogestrel with testosterone pellets for suppression of the pituitary-testicular axis in normal men

Prototype hormonal male contraceptive regimens generally achieve only incomplete suppression to azoospermia with potentially adverse metabolic effects. We have carried out a short-term dose-finding study to investigate the potential of an oral gestogen, desogestrel, with testosterone pellets. Normal men received a single dose of 300 mg testosterone with 75 microg, 150 microg or 300 microg desogestrel daily for 8 weeks (n = 10 per group). LH and FSH were rapidly suppressed, with little difference between groups. Testosterone concentrations fell slightly during treatment with evidence of a linear dosage effect. Plasma inhibin B showed minor changes, but in seminal plasma it was suppressed, becoming undetectable in all men in the 300 microg desogestrel group. There were no significant changes in lipoproteins, fibrinogen or sexual behaviour during treatment, and minor falls in haematocrit and haemoglobin concentration. Sperm concentration fell in a dose-dependent manner, with three men, one man and seven men in the three groups respectively achieving severe oligozoospermia (<3 x 10(6)/ml), and three men achieving azoospermia in the 300 microg group despite the short duration of the study. The combination of oral desogestrel with depot testosterone thus results in profound suppression of gonadotrophin secretion without adverse metabolic or behavioural effects. Desogestrel with a long-acting testosterone preparation is a promising approach to hormonal male contraception.

Potential impact of hormonal male contraception: cross-cultural implications for development of novel preparations

The prospect of a hormonal male contraceptive is no longer distant. Data on the potential impact of this improvement in contraceptive provision, however, is limited, particularly between different cultures. We have therefore carried out a multi-centre study to assess men's attitudes to proposed novel hormonal methods. Questionnaire-based structured interviews were administered to men in Edinburgh, Cape Town, Shanghai and Hong Kong. Approximately 450 men were interviewed in Edinburgh, Shanghai and Hong Kong, and a slightly larger group (n = 493) in Cape Town to give samples (n > 150) of black, coloured and white men. Knowledge of existing male and female methods of contraception was high in all centres and groups. The majority of men welcomed a new hormonal method of contraception, 44-83% stating that they would use a male contraceptive pill. Overall, a pill was more acceptable than an injectable form (most popularly given at 3-6 month intervals); long-acting implants were least so except in Shanghai. Familiarity with comparable female methods appeared to influence acceptability, for both oral and injectable methods. Hong Kong was the only centre where a male method (condom) was currently the most commonly used; men there appeared to rate the convenience of condoms highly while being least likely to think that they provided effective protection against pregnancy compared to other centres, and were least enthusiastic about novel male methods. The acceptability of potential male hormonal methods of contraception was high in some groups but showed wide variability, determining factors including cultural background and current contraceptive usage. These results suggest that the emerging emphasis that men should have greater involvement in family planning will be substantiated when appropriate contraceptive methods become available.

Oestradiol enhances testosterone-induced suppression of human spermatogenesis

The aim of this study was to determine for the first time in humans, the efficacy of adding a low dose oestradiol to a suboptimally suppressive testosterone dose in a depot hormonal regimen to suppress spermatogenesis in healthy eugonadal men. Twenty-six healthy men were randomized into groups that were treated by a single subdermal implantation of either 600 mg testosterone alone (T; n = 11) or together with 10 mg (TE10, n = 7) or 20 mg (TE20, n = 8) oestradiol. Administration of oestradiol produced a dose-dependent increase in peak plasma oestradiol at 1 month and prolonged suppression of plasma LH and FSH leading to significantly enhanced suppression of sperm output. Despite the augmented spermatogenic suppression, there was no significant difference in the proportions achieving azoospermia (6/26, 23%) or severe oligozoospermia (<1 or <3 x 10(6) spermatozoa per ml, 7/26, 27%) and overall these proportions were inadequate to provide reliable contraception according to the standards identified in World Health Organization male contraceptive efficacy studies. Total and free testosterone remained within the eugonadal reference range for young men throughout the study. While the lower oestradiol dosage had minimal spermatogenic suppression effects, the higher dose produced dose-limiting adverse effects of androgen deficiency and/or oestrogen excess between the fourth and sixth month of the study. This appeared to be due to the unexpectedly prolonged, low concentration of oestradiol release from the oestradiol implants. There were no significant treatment-related changes in body composition, lipids, prostate-specific antigen, haematological or biochemical variables. Thus oestradiol has a low therapeutic window and dose-limiting side-effects at dosages that fail to achieve the uniform azoospermia required of an effective male hormonal contraceptive regimen.