Male Contraception

Unintended pregnancy is a global public health problem. Despite a variety of female contraceptive options, male contraceptive options are limited to the condom and vasectomy. Condoms have high failure rates and surgical vasectomy is not reliably reversible. There is a global need and desire for novel male contraceptive methods. Hormonal methods have progressed the furthest in clinical development and androgen plus progestin formulations hold promise as a marketable, reversible male contraceptive over the next decade. Investigators have tested androgen plus progestin approaches using oral, transdermal, subdermal, and injectable drug formulations and demonstrated the short-term safety and reversibility of hormonal male contraception. The most commonly reported side effects associated with hormonal male contraception include weight gain, acne, slight suppression of serum high-density cholesterol, mood changes, and changes in libido. Efficacy trials of hormonal male contraceptives have demonstrated contraceptive efficacy rates greater than that of condoms. Although there has been less progression in the development of nonhormonal male contraceptives, potentially reversible vaso-occlusive methods are currently in clinical trials in some countries. Various studies have confirmed both men and women's desire for novel male contraceptives. Barriers to development include an absence of investment from pharmaceutical companies, concerns regarding side effects and spermatogenic rebound with hormonal methods, and lack of clear reversibility and proven effectiveness of nonhormonal methods. The ultimate availability of male contraceptives could have an important impact on decreasing global unintended pregnancy rates (currently 40% of all pregnancies) and will be a step towards reproductive justice and greater equity in family planning.

Pharmacokinetics of 7 alpha-methyl-19-nortestosterone (MENT) delivery using subdermal implants in healthy men

We studied the pharmacokinetics of 7 alpha-methyl-19-nortestosterone (MENT), a potent synthetic androgen, administered by subdermal implants. The implants contained 112 +/- 4 mg of MENT acetate in a polyethylene vinyl acetate copolymer. MENT acetate released from the implants is rapidly hydrolyzed to MENT in vivo. Fifteen healthy Finnish men were randomized to have either one, two, or four implants inserted in the medial aspect of the upper arm. The implants remained in place for 4 weeks. Blood samples were obtained before implant insertion, 1, 2, 3, and 4 weeks after insertion, and 1 and 2 weeks after removal. Serum MENT concentrations were determined by gas chromatography with mass selective detection. The MENT levels attained in each implant group remained at a steady level during the 4 weeks of implant use. The mean steady state MENT concentrations in the one, two, and four implant groups were 0.6, 1.4, and 2.3 nmol/L, respectively. Serum MENT concentrations during implant use were clearly dose dependent; the between-subject effect of implants as well as the differences between each pair of groups were all statistically significant. The release rate of MENT from one, two, and four implants was calculated to be approximately 0.3, 0.8, and 1.3 mg/day, respectively. This study suggests that MENT acetate implants are a promising method for long-term androgen administration in hypogonadism and male contraception.

The use of testosterone as a male contraceptive

Testosterone functions as a contraceptive by suppressing secretion of the pituitary gonadotropins luteinizing hormone and follicle stimulating hormone. Low levels of these hormones decrease endogenous testosterone secretion from the testis and deprive developing sperm of the signals required for normal maturation. Interference with sperm maturation causes a decline in sperm production and can lead to reversible infertility in men, raising the possibility that testosterone could be utilized in a commercially available contraceptive. To this end, testosterone has been studied alone and in combination with either gonadotropin releasing hormone analogues or progestins in efforts to improve its contraceptive efficacy. In this chapter, we will review efforts to use testosterone to create a safe, convenient, efficacious contraceptive method for men.

Safety, tolerability, and pharmacokinetics of a novel, selective antiprogestagen (Org 31710) in healthy male volunteers

The safety and tolerability as well as pharmacokinetics of a new selective antiprogestagen, Org 31710, were studied after oral administration of single doses of 10, 25, 50, or 75 mg to 24 healthy male volunteers. Per dose-group, five subjects received active and one subject received placebo treatment. In subjects receiving 75 mg, the effects of Org 31710 on serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone were also studied. No adverse or seriously adverse events were observed. All doses of Org 31710 were well tolerated. Characterization of the Org 31710 plasma pharmacokinetics revealed a statistically significant deviation from linearity: the dose normalized Cmax (nCmax) and dose normalized area under the curve (nAUC) values were significantly lower for the higher dosages (p < 0.05). Furthermore, tmax tended to decrease (from 1.6 to 0.9 h), whereas the elimination half-life (t1/2) tended to increase (from on average 45 to 57 h) with increasing dose. Org 31710 did not have any effect on serum levels of FSH, LH, and testosterone. In conclusion, Org 31710 appears to be a safe and well-tolerated compound in the dosage range studied.

Low dose of cyproterone acetate and testosterone enanthate for contraception in men

After a control phase, 10 normal men received cyproterone acetate (CPA) at a dose of 25 mg/day (CPA-25; n=5) or 12.5 mg/day (CPA-12.5; n=5) plus testosterone enanthate (TE) 100 mg/week, for 16 weeks. Throughout the study sperm counts were performed every 2 weeks, and luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, biochemical and haematological tests were performed every 4 weeks. All five men in group CPA-25 and three men in group CPA-12.5 achieved azoospermia. One man in group CPA-25 was azoospermic by week 12 of hormone administration, but had a sperm count of 0.1 x 10(6)/ml at week 16. Time to azoospermia was 9.0+/-1.3 and 8.7+/-0.7 weeks in groups CPA-25 and CPA-12.5 respectively. Gonadotrophins were decreased by week 4 of hormone administration, remained around the minimum detectability of the assay for the duration of hormone administration and returned to baseline after stopping hormone administration. Testosterone values did not change. No change in any biochemical parameters was found. Haematological parameters were decreased at week 16 of hormone administration and returned to baseline after stopping hormone administration. In conclusion, these results suggest that an hormonal regimen consisting of testosterone plus a progestin with anti-androgenic properties holds promise as an effective, safe and reversible male contraceptive.

Use of norethisterone and estradiol in mini doses as a contraceptive in the male. Efficacy studies in the adult male bonnet monkey (Macaca radiata)

Administration of norethisterone (NET) or NET + estradiol benzoate using an Alzet minipump or as once-a-month intramuscular injection of their depot forms, NET-enanthate (NET-EN) and estradiol valerate (E-val), resulted in azoospermia in all monkeys (n = 13) within 60 to 150 days of treatment. Although addition of depot form of testosterone (T, 20 mg/month) to the regimen restored the behavioral response typical of a normal male, it did not reverse the azoospermic state. Serum T (heightened nocturnal) levels were significantly reduced (> 85%, p < 0.001) in all the treated groups. Evidence for blockade in spermatogenesis following treatment was obtained by DNA flow cytometry. Following withdrawal of treatment, the T level was restored to normalcy within 15 days but 120 days more were required for the animals to exhibit normal sperm counts. In conclusion, the efficacy of once-a-month injection of relatively low doses of NET-EN + E-Val to bring about azoospermia in monkeys, in a relatively short time, has been demonstrated. As the results are uniform and reproducible, it appears desirable that this steroid regimen be tested in man for its contraceptive efficacy.

Phase II clinical trial of a vas deferens injectable contraceptive for the male

Following up on an earlier clinical trial demonstrating the safety of an intra-vas deferens injection of a contraceptive drug named Risug, comprised of styrene maleic anhydride (SMA) in a solvent vehicle of dimethylsulphoxide (DMSO), a study to assess the contraceptive effectiveness of a specific dose (60 mg) of SMA bilaterally was planned and implemented. Male subjects and their wives with normal reproductive profiles were the volunteer subjects. The wives were not using any contraceptives. The results reconfirm the safety and show that for a period of at least 1 year, the treatment leads to azoospermia in the male and gives pregnancy protection.

Gossypol-induced hypokalemia and role of exogenous potassium salt supplementation when used as an antispermatogenic agent in male langur monkey

In our earlier study, we have observed that hypokalemia in langur monkeys, following gossypol acetic acid (GAA) treatment (5 mg dose level) when used as an antispermatogenic agent, and potassium salt supplementation partially maintained body potassium level of the animals. The aims of the present investigation was to confirm further occurrence of hypokalemia in the monkey (comparatively at two higher dose levels) and the role of potassium salt in preventing occurrence of gossypol-induced hypokalemia. Highly purified gossypol acetic acid alone at two dose levels (7.5 and 10 mg/animal/day; oral) and in combination with potassium chloride (0.50 and 0.75 mg/animal/ day; oral) was given for 180 days. Treatment with gossypol alone as well as with the supplementation of potassium salt resulted in severe oligospermia and azoospermia. Animals receiving gossypol alone showed significant potassium deficiency with signs of fatigue at both dose levels. Enhanced potassium loss through urine was found in potassium-deficient animals, whereas animals receiving gossypol acetic acid plus potassium salt showed normal serum potassium with a less significant increase in urine potassium level during treatment phases. Other parameters of the body remained within normal range except gradual and significant elevation in serum transaminases activity. The animals gradually returned to normalcy following 150 and 180 days of termination of the treatment.

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

Hormonally induced azoospermia induced by weekly im injections of testosterone enanthate provides effective and reversible male contraception, but more practical regimens are needed. Given our previous findings that six 200-mg pellets implanted subdermally produced more stable, physiological T levels and reduced the delivered T dose by more than 50% while maintaining equally effective suppression of sperm output with fewer metabolic side-effects than weekly 200-mg testosterone enanthate injections, we sought in this study to determine 1) whether further dose-sparing could be achieved by lower testosterone doses while maintaining efficacy and 2) the efficacy of adding a depot progestin to a suboptimally suppressive depot testosterone dose as a model depot progestin/androgen combination male contraceptive. Healthy volunteers were randomized into groups (n = 10) who received either of two lower T doses (two or four 200-mg T pellets) or four 200-mg T pellets plus a single im injection of 300 mg depot medroxyprogesterone acetate (DMPA). Two T pellets (400 mg, 3 mg/day) had a negligible effect on sperm output. Four T pellets (800 mg, 6 mg/day) suppressed sperm output between the second to fourth postimplant months; output returned to normal by the seventh postimplant month, although only 4 of 10 men became azoospermic or severely oligozoospermic (< 3 mol/L/mL). The addition of a depot progestin markedly increased the extent, but not the rate, of sperm output suppression, with 9 of 10 becoming azoospermic and 10 of 10 becoming severely oligozoospermic. There were no serious adverse effects during the study. Plasma total and free testosterone levels remained within the eugonadal range at all times with each treatment. Plasma epitestosterone was suppressed by all 3 regimens, consistent with a dose-dependent inhibition of endogenous Leydig cell steroidogenesis. Plasma LH and FSH measured by a two-site immunoassay were suppressed in a dose-dependent fashion by T and further suppressed by the addition of DMPA. Sex hormone-binding globulin levels were decreased by DMPA, but not by either T dose. Prostate-specific antigen and lipids (total, low or high density lipoprotein cholesterol, and triglycerides) were not significantly changed in any group. Thus, a depot testosterone preparation with zero order release must be delivered at between 6-9 mg/day to provide optimal (but not uniform) efficacy at inducing azoospermia. The addition of a single depot dose of a progestin to a suboptimal testosterone dose (6 mg/day) markedly enhances the extent, but not the rate, of spermatogenic suppression, with negligible biochemical androgenic side-effects. These findings provide a basis for the use of a progestin/androgen combination depot for hormonal male contraception.

Male participation and responsibility in fertility regulation. Research

Women's health advocates have consistently called for men to take more personal responsibility for reproductive health and fertility regulation. The UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction has carried out several studies on men's needs and preferences with regard to methods of fertility regulation, especially in less-developed countries. Although there were significant intercountry differences, a high percentage of men studied knew at least one method of fertility regulation, most often the condom. On average, some 75% of men approved of the use of family planning, even in developing countries, which is contrary to the commonly held notion that men in these countries are against family planning. It is not clear from the data, however, how many men approve the use of male methods, but in spite of this, the actual use of such methods was very low. Condom use was low even in the countries that are relatively more effected by the AIDS pandemic. Vasectomy use remains negligible in Africa (0.1%) and Latin America (1%), although it was used by 10% of respondents in East Asia.

Examining male roles in population policies and family planning programs

"This paper will discuss the following: why population policies and programs have traditionally focused on women; what the limitations of current male contraceptives are and why research into new methods [has] proved unfruitful; and why these policies and programs would be more productive if they were to direct more attention toward men."

Hormonal male contraception: progress and prospects for the 21st century

During the second half of the 20th century, progress in developing novel, practical contraceptive methods for men has lagged significantly behind developments for women. Despite the lack of reliable, reversible methods, men throughout the world continue to be strongly involved in family planning but a greater involvement will require more attractive and reliable contraceptive options for men. The closest to fruition are hormonal methods the features of which are reviewed. Landmark WHO contraceptive efficacy studies have established that hormonally-induced azoospermia provides highly effective and reversible contraception for at least 12 months with minimal short-term side effects. Even among the small subgroup of men who remain oligozoospermic during hormonal suppression, good contraceptive efficacy is achieved. The present goals are to develop improved second generation hormonal regimens which provide more uniform azoospermia to obviate the need for monitoring of sperm output and to develop long-acting depot testosterone formulations used alone or with additional gonadotrophin suppressive agents such as progestins or GnRH antagonists. Significant obstacles to progress are the flight of industry from contraceptive R&D dur to the financial deterrent posed by the product liability crisis as well as the low priority accorded male reproductive health. Together those will determine whether the range of contraceptive options available to our children in the 21st century will improve, or whether the historically recent unbalanced increase in reliance on women for family planning will continue.

Effect of testosterone enanthate on serum lipoproteins in man

Sixty-three normal Caucasian men were administered intramuscular testosterone enanthate (TE) 200 mg i.m. weekly for 12 months as part of a male contraceptive trial. This dose of TE caused a 2.5-fold increase in trough serum testosterone concentrations. High density lipoprotein cholesterol (HDL-C) was significantly depressed from pretreatment concentration of 1.19 +/- 0.04 nmol/l to 1.03 +/- 0.04 mmol/l after 12 weeks of treatment, and remained suppressed for the duration of treatment (p < 0.001). There were no changes in serum concentration of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) or triglycerides (TG) during treatment, but the concentrations of TC and LDL-C were depressed at three months post-treatment. There was a sustained elevation in LDL-C:HDL-C ratio during TE treatment (p < 0.005), from 3.41 +/- 0.15 pretreatment to 3.88 +/- 0.19 after 12 weeks of TE treatment. Sex hormone binding globulin (SHBG), but not testosterone (T) or estradiol (E2), was significantly associated with HDL-C (r = 0.83, p = 0.001). Lipoprotein (a) (Lp(a)) was measured in a subgroup of 33 men: serum concentration fell from 187 +/- 45 mg/l pretreatment to 140 +/- 35 mg/l after 16 weeks of TE treatment (p < 0.01).

Potential of testosterone buciclate for male contraception: endocrine differences between responders and nonresponders

Suppression of serum LH and FSH, by testosterone (T) alone or in combination with other agents, has proved to be the most promising approach to male contraception. T enanthate, the only androgen preparation tested in male contraceptive efficacy trials so far, must be injected every week due to its short terminal elimination half-life of 4.5 days and leads to supraphysiological T serum levels. A new T ester synthesized under WHO and NIH auspices, testosterone buciclate (TB), showed a favorable pharmacokinetic profile, with a terminal half-life of 29.5 days when tested in hypogonadal men. Here we describe the results of the first clinical trial with TB for male contraception. After two control examinations, normal healthy male volunteers were given a single im injection of 600 mg TB (group I; n = 4) and 1200 mg TB (group II; n = 8) on day 0. Follow-up examinations were performed every 2 weeks up to week 32. In both groups mean serum T levels remained in the normal physiological range throughout the study course. Serum levels of dihydrotestosterone (DHT) showed a dose- and time-dependent increase, with serum levels slightly above the normal range in group II for several weeks and a maximal concentration of 3.8 +/- 0.5 nmol/L (mean +/- SE) in week 6. No suppression of spermatogenesis to oligozoospermia was observed in group I. However, in group II, spermatogenesis was suppressed to azoospermia in three of eight volunteers in week 10 that persisted up to weeks 14, 20, and 22, respectively. In these three men, LH and FSH were suppressed by TB injections to the respective assay detection limits, whereas in the other five subjects, mean serum levels were only decreased to values near the lower normal limit for LH and FSH, respectively. In addition, throughout the study course, a significant difference in serum sex hormone-binding globulin was detected between the responders (mean values, 21.2-26.4 nmol/L) and nonresponders (mean values, 36.2-46.3 nmol/L). Serum levels of LH as well as total and free T at baseline and after TB injection were lower in the responders than in the nonresponders. Both subgroups showed similar increases in serum LH and FSH after GnRH stimulation. In a newly introduced GnRH antagonist suppression test, serum LH and T were decreased to significantly lower levels in the responders. These results indicate a different hormonal equilibrium and probably different susceptibility to feedback regulation of the responders compared to the nonresponders.(ABSTRACT TRUNCATED AT 400 WORDS)

Prospects for new hormonal male contraceptives

Overpopulation is a paramount global crisis, as it underlies virtually all major worldwide problems, including poverty, malnutrition, and warfare. It is imperative that proliferation be curbed by expediting reductions in fertility. This article discusses the demand for and acceptability of male contraceptives and the process of spermatogenesis. Endocrine control of spermatogenesis, and potential sites for disruption of male fertility, including steroid combinations and GnRH agonists and antagonists are reviewed also. Risks and benefits of these approaches are considered.

The potential of mild testicular heating as a safe, effective and reversible contraceptive method for men

A preliminary assessment of the contraceptive efficacy of a daily mild increase (1-2 degrees C) in testicular temperature during waking hours is reported in nine couples using two techniques of non-surgical fixation of the testes close to the inguinal canal. With technique 1, immobilization was achieved by passing the penis and the empty scrotum through a hole made in close-fitting underwear; there was one pregnancy, from a man who stopped the heating after 7 weeks, for 42 cycles of exposure in three couples. With technique 2, immobilization was achieved by adding a ring of soft material surrounding the hole in the underwear; there was no pregnancy for 117 cycles of exposure in six couples. Reversibility and safety were assessed. These preliminary results suggest that a daily mild increase in testicular temperature could be a potential contraceptive method for men.

Possible physiological bases for contraceptive techniques in the male

Aspects of the physiology of the testis and epididymis are discussed which might be relevant to future methods of contraception in the male. These include the blood-testis barriers, both at the tubular and vascular level, testicular and scrotal thermoregulation and maturation of spermatozoa in the epididymis. Possible adverse consequences of interfering with spermatogenesis are also considered, such as reduced endocrine responsiveness of the testis, increased incidence of genetic abnormalities and abnormal development of embryos produced by sub-fertile males.

Male contraception: hormonal, mechanical and other

Methods of male contraception that have been developed so far have mainly focused on the inhibition of spermatogenesis through suppression of the hypothalamo-pituitary secretion of gonadotrophins, and simultaneous supplementation with androgens. These methods include the use of combinations of progestogens or luteinizing hormone-releasing hormone antagonists and testosterone derivatives, or high dose testosterone. Though effective contraception can be obtained, side-effects and/or the high cost of treatment limit the widespread use of these approaches. Inhibition of sperm maturation in the epididymis, or direct interference with spermatogenic cells or the cells of Sertoli by e.g. gossypol have been abandoned because of toxic side-effects. Voluntary sterilization by vasectomy is the most commonly used method of male contraception, but its surgical nature, problematic reversibility and suspected link with subsequent prostate cancer render the method far from ideal. Non-surgical vas occlusion may overcome some of these problems, but data on long-term side-effects and reversibility are lacking. New contraceptive developments should focus on interfering with highly specific aspects of spermatogenesis such as unique enzymatic processes and intercellular communication through cytokines, or application of antibodies against antigens of the epididymis or the spermatozoa. Only through better understanding of normal and pathological spermatogenesis will it be possible to develop an acceptable male contraceptive.

The value and use of different contraceptive methods

Reductions in the rates of maternal and child mortality as well as in demographic growth are directly linked to contraceptive usage. The development and availability of safer, improved contraceptives which are convenient to use could be expected to be used by a larger group of individuals and thus make an impact on reproductive health as well as on population growth rates. Such arguments have been used to support contraceptive research. This article deals with some of the developments that have occurred as a consequence of such efforts.