The influence of pharmaceutical compounds on male fertility

1. Steroid hormones can affect spermatogenesis and thereby fertility directly and/or indirectly. All antigonadotropically active steroids inhibit spermatogenesis via inhibition of gonadotropin secretion, mainly that of H. Androgens and steroids occurring in the biosynthetic chain of testosterone synthesis have a direct promoting effect on spermatogenesis if applied in high doses. It has not been possible as yet to make clinical use of this positive effect since it is obviously not possible to achieve the necessary intratesticular androgen concentrations. 2. As concerns the different androgens and the steroids in the androgen biosynthetic chain, and also all synthetic anabolics, there is no parallelism between the direct spermatogenic activity, the androgenic activity and the antigonadotropic activity. 3. Estrogens and synthetic gestagens do not inhibit spermatogenesis directly at the testicular level. All effects of estrogens can be abolished experimentally by adequate substitution with gonadotropins or androgens, or a combination of androgens and gonadotropins. 4. Only those antiandrogens inhibit spermatogenesis with additional antigonadotropic properties (e.g. cyproterone acetate). Pure antiandrogens, like flutamide or cyproterone, have a slight and transient influence on spermatogenesis at the most. If at all, they merely cause transient subfertility. 5. Beside steroids and several centrally active pharmaceutics (e.g. psychotropic drugs and several antihypertensive compounds), only siloxanes and methallibur seem to affect spermatogenesis via inhibition of gonadotropin secretion. Other antispermatogenic agents act by inhibition of mitosis (Colchicine, alkylating agents) or presumably via damage of the Sertoli cells. 6. Based on present knowledge, contraception in men could be principally managed by administration of a) androgens alone, b) gestagen/androgen combinations, c) estrogen/androgen combinations, d) certain antiandrogens. 7. The difficulties of contraception in men by steroid hormones or steroid hormone combinations have been pointed out. As regards the usefulness of antiandrogens for contraception, no definite conclusions can be drawn at the moment. All non-steroidal inhibitors of spermatogenesis which have been found up to the present are not suitable because of toxic effects.

Gossypol blood levels and inhibition of spermatogenesis in men taking gossypol as a contraceptive. A multicenter, international, dose-finding study

The safety and efficacy of gossypol continues to be controversial. The aim of this study was to evaluate gossypol as a contraceptive pill for men at doses lower than those previously prescribed and in men from various ethnic origin. A total of 151 men from Brazil, Nigeria, Kenya, and China were divided into two groups. Both groups received 15 mg gossypol/day for 12 or 16 weeks to reach spermatogenesis suppression. Subjects were then randomized to either 7.5 or 10 mg/day for 40 weeks. In addition, 51 men were enrolled as a control group. In all, 81 subjects attained spermatogenesis suppression. Only one man discontinued treatment because of tiredness. Potassium levels fluctuated within the normal range. FSH increased consistently. Testicular volume decreased, but after discontinuation, values returned to levels not statistically different from admission. Of 19 subjects on the 7.5 mg/day dose group, 12 recovered sperm counts >20 million/mL within 12 months of discontinuing gossypol. In the 10 mg/day group, sperm counts recovered in only 10 of 24 subjects. Eight of the 43 patients remained azoospermic 1 year after stopping gossypol. All men diagnosed with varicocele failed to reverse spermatogenesis suppression. Gossypol blood levels indicated that sperm suppression occurs independently of concentration, whereas spermatogenesis recovery appears to be concentration-dependent. Gossypol may become a medical alternative to surgical vasectomy when the delay in onset of infertility is acceptable. When taken for 1 year, gossypol causes no reduction in sexual desire or frequency of intercourse. The possibility of reversal, occurring in 51% of the men on this regimen within 1 year after stopping gossypol, is an advantage of this compound as compared with surgical sterilization in many parts of the world.

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.

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.

Physiological relationships between inhibin B, follicle stimulating hormone secretion and spermatogenesis in normal men and response to gonadotrophin suppression by exogenous testosterone

Inhibin has been postulated to be secreted by Sertoli cells in response to follicle stimulating hormone (FSH) and in turn to exert an inhibitory effect on FSH production. We have investigated this relationship using an assay specific for dimeric inhibin B. A total of 56 normal men received 200 mg testosterone enanthate (TE) i.m. weekly, for 65 +/- 1 weeks in a trial of hormonal male contraception. Before treatment a significant negative correlation between inhibin B and FSH concentration (r = 0.49, P < 0.001) was observed. During TE treatment, luteinizing hormone (LH) and FSH were rapidly suppressed. This was followed by a parallel decline in inhibin B and sperm concentration. During the early recovery phase, inhibin B concentrations remained suppressed in men who showed a delay in resumption of spermatogenesis, despite higher FSH concentrations. Inhibin B returned to pretreatment concentrations after 24 weeks recovery, when the inverse relationship with FSH was restored. Our results showed the expected inverse physiological relationship between inhibin B and FSH in normal men, with a decline during TE treatment and alpha subsequent resumption of the inverse relationship during recovery. These data clearly support the hypothesis that inhibin B plays a physiological role in the feedback control of FSH secretion, and reflects FSH-stimulated Sertoli cell function.

Contraceptive efficacy and adverse effects of testosterone enanthate in Thai men

In conclusion, the present study demonstrated that induced severe oligozoospermia or azoospermia by weekly testosterone enanthate injection was sufficient for male contraception. The low rates of discontinuation due to side-effects of the hormone and incidental medical conditions in this study confirms the safety and acceptability of such androgen administration found in studies with up to 18 months exposure. The long-term hazards remain uncertain and require investigation for risk. The possible long-term benefits from androgen use for bone, muscle and blood metabolism will also need to be assessed before the net risk-benefit effects of an androgen-containing regimen can be fully evaluated. In summary, the contraceptive efficacy for male contraception in this study demonstrated that weekly injections of testosterone enanthate can provide safe and effective contraceptive protection. The practicability of this approach may be improved by the use of longer-acting testosterone preparations which are under development.

Suppression of spermatogenesis by testosterone enanthate in Thai men

To investigate the effect of testosterone enanthate on suppression of spermatogenesis in Thai men, 17 normal Thai men were given 200 mg testosterone enanthate weekly by intramuscular injection. During treatment, semen was collected regularly to monitor spermatogenesis. Median times for the first semen sample reaching sperm concentration threshold of 5, 3, 1 and 0 million/ml were 58, 70, 84, and 85, respectively. Subsequently, all men became azoospermic. Among 17 men entering the efficacy phase, 14 (82.3%) achieved consistent azoospermic from the beginning of efficacy phase, the remaining 3 (17.7%) were initially severe oligozoospermic but later became azoospermic. Only one case achieved consistent oligozoospermia but did not achieve azoospermia within 6 months. After stopping injection, sperm first reappeared in the ejaculate of formerly azoospermia men at 73 days. Recovery of sperm output to normal sperm concentration (> 20 million/ml) was achieved by all men at a median time of 3.9 months and recovery to their own baseline in one year after the last injection was established in 13/17 (76.5%) at a median time of 4.9 months, respectively. In conclusion, testosterone enanthate alone is effective in suppression of spermatogenesis for male hormonal contraception due to the high rate of azoospermia induced, which is known to ensure reliable and effective, reversible contraception.

A combined regimen of cyproterone acetate and testosterone enanthate as a potentially highly effective male contraceptive

In this study we tested the effectiveness of the combined administration of cyproterone acetate (CPA) and testosterone enanthate (TE) in suppressing spermatogenesis. After a control phase of 3 months, 15 normal men were randomized to receive TE (100 mg/week) plus CPA at a dose of 100 mg/day (CPA-100; n = 5) or 50 mg/day (CPA-50; n = 5) or TE (100 mg/week) alone (n = 5) for 16 weeks. Semen analysis was performed every 2 weeks. Every 4 weeks, fasting blood samples were drawn for the measurement of LH, FSH, testosterone, estradiol, and biochemical and hematological parameters; subjects underwent a physical examination; and they and their partners filled in a sexual and behavioral questionnaire. Regardless of the dose, each of the 10 subjects receiving CPA plus TE became azoospermic, whereas only 3 of 5 subjects treated with TE alone achieved azoospermia. Times to azoospermia were 6.8 +/- 0.5, 8.4 +/- 1.0, and 14.0 +/- 1.2 weeks in groups CPA-100, CPA-50, and TE alone, respectively (P = NS). Throughout treatment, both gonadotropins tended to be higher in the TE alone group than in the other groups. This difference was mostly due to the higher gonadotropin levels present in the 2 men treated with TE alone that remained oligospermic. No difference in testosterone or estradiol levels was found among the groups. No significant change in lipoprotein levels or liver function tests could be detected. In the CPA-100 and CPA-50 groups, hemoglobin, hematocrit, and red blood cells were lower at the end of the treatment phase, whereas no change was detected in TE alone group. A tendency for a decrease in body weight was detected in subjects treated with CPA, whereas there was no change in subjects receiving TE alone. At the end of the treatment phase, a decrease in testis size was present in all groups. There was no significant change in sexual function, aggressive behavior, mood states, or satisfaction with relationship in any group. These results suggest that the combined administration of CPA and TE is very effective in suppressing spermatogenesis and may represent a promising regimen for reversible contraception in males.

Comparison between testosterone enanthate-induced azoospermia and oligozoospermia in a male contraceptive study. III. Higher 5 alpha-reductase activity in oligozoospermic men administered supraphysiological doses of testosterone

The administration of exogenous testosterone (T) to eugonadal men causes suppression of gonadotropin secretion and thus of spermatogenesis. This is currently being investigated as a possible method of hormonal male contraceptive, but complete suppression of spermatogenesis to azoospermia is induced in only 50-70% of Caucasian men; the remainder maintain a low rate of spermatogenesis. The basis for this polymorphism in response is unclear. The enzyme 5 alpha-reductase (5 alpha R) converts T to dihydrotestosterone (DHT) and is important in determining the magnitude of the androgen stimulus in some tissues. We investigated whether the maintenance of spermatogenesis in men remaining oligozoospermic while receiving suppressive doses of T is associated with evidence of increased 5 alpha R activity. Thirty-three normal men were given 200 mg T enanthate (TE), im, weekly in a clinical trial of hormonal male contraception. The MCR of T (MCRT) and the conversion ratio of T to DHT (CRT-DHT) were measured by infusion of [3H]T, plasma levels of DHT and androstanediol glucuronide (AdiolG) were measured by RIA, and 24-h urinary steroid metabolites were measured by capillary column gas chromatography. Sperm density decreased in all men; 18 achieved azoospermia by 20 weeks of treatment, and the remainder had a mean sperm density of 2.0 +/- 0.8 x 10(5)/mL at that time. This treatment caused increases in plasma T levels and MCRT, but with no differences between azoospermic and oligozoospermic responders. There were no differences in CRT-DHT plasma DHT, or AdiolG before treatment, but after 16 weeks, CRT-DHT had increased in the oligozoospermic responders, but not in the azoospermic responders. TE treatment increased plasma DHT and AdiolG levels in both groups, but the increases in both 5 alpha R metabolites were significantly greater in the oligozoospermic responders. Urinary excretion of etiocholanolone and androsterone was increased after 16 weeks of TE treatment, but did not differ between the two groups, andetiocholanolone/androsterone ratios did not differ greatly from unity. There was no change in urinary excretion of tetrahydrocortisol, allo-tetrahydrocortisol, or cortisone after 16 weeks of TE treatment in either group. These results suggest that after TE administration there is a selective increase in 5 alpha R activity in those men who remain oligozoospermic, but not in those becoming azoospermic. This difference in the androgenic milieu may underlie the incomplete suppression in the oligozoospermic responders, in whom a low rate of spermatogenesis is maintained despite the apparent absence of gonadotropins.

Combined administration of levonorgestrel and testosterone induces more rapid and effective suppression of spermatogenesis than testosterone alone: a promising male contraceptive approach

Studies using high dose testosterone (T) administration in normal men as a male contraceptive have resulted in azoospermia rates of only 50-70%. Previous studies of T and progestogen combinations have shown comparable rates of azoospermia, but have been uncontrolled or used T in doses less than that associated with maximal suppression of sperm production. We conducted a randomized, placebo-controlled, single blind trial comparing 6 months of T enanthate administration (100 mg, im, weekly) with the same dose of T enanthate in conjunction with the progestogen levonorgestrel (LNG; 500 micrograms, orally, daily) in 36 normal men, aged 20-42 yr (n = 18 in each group). The primary end points were induction of azoospermia or severe oligospermia (< 3 million sperm/mL). The combination of T plus LNG was much more effective in suppressing sperm production than T alone. Sixty-seven percent of the T plus LNG group (12 of 18) and 33% of the T alone group (6 of 18) achieved azoospermia by 6 months (P = 0.06). Severe oligospermia or azoospermia developed in 94% of the T plus LNG (17 of 18) group compared to 61% of the T alone group (11 of 18; P < 0.05). T plus LNG also suppressed sperm production more rapidly than T alone. Time to azoospermia was 9.9 +/- 1.0 vs. 15.3 +/- 1.9 weeks in the T plus LNG and T alone groups, respectively (mean +/- SEM; P < 0.05). Serum high density lipoprotein cholesterol decreased 21.7 +/- 3.6% in men given T plus LNG (P < 0.05), compared to only a 1.8 +/- 3.8% decrease in men in the T alone group. Average weight gain was 5.3 +/- 0.8 kg in the T plus LNG group and 2.3 +/- 0.9 kg in the T alone group (P < 0.05). Acne and increase in hemoglobin were similar in the two groups. We conclude that combination hormonal therapy with T plus a progestogen might offer a reversible male contraceptive approach with a more rapid onset of action and more reliable induction of both azoospermia and severe oligospermia than T alone.

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.

Prolactin injection, a new contraceptive method: experimental study

"Prolactin injection" is presented as a new contraceptive method. The method was tested in dogs. The dogs in the test group were injected with prolactin (PRL) in a dose of 600 micrograms/kg of body weight weekly for 6 months. During this period, the testicles, semen, reproductive hormones, renal function, and serum sodium and potassium were examined periodically. Testicular biopsy was obtained after 3 and 6 months of PRL injection. These investigations were repeated during the 6 months following withdrawal of the drug. Sperm count decreased to azoospermia in 3 months after PRL administration with decrease of sperm motility and increase of abnormal forms. Testicular biopsy showed degenerated seminiferous tubules. Reproductive hormones, renal function, and serum sodium and potassium revealed insignificant change (P > 0.05). Dog mating during the period of PRL administration induced no pregnancy. After 3 months of drug withdrawal, the sperm count normalized and dog mating produced pregnancy; offsprings showed no anomalies. The study demonstrates that PRL administration has the potential to be developed as a reversible male contraceptive.

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.

Body composition and muscle strength in healthy men receiving testosterone enanthate for contraception

To determine the effect of androgens on body composition and muscle strength, we measured fat-free mass (kg), fat mass (kg), and bone density (g/cm2) by dual x-ray absorptiometry, and muscle strength (Newton meters) by dynamometry in a controlled, prospective study involving 13 nonathletic men receiving testosterone enanthate 200 mg/week in for 6 months and 8 healthy controls. Biochemical markers of bone turnover were measured in the treated subjects at baseline and 6 months. In the treated subjects at 6 months, fat-free mass (mean +/- SEM) increased by 9.6 +/- 1.0% (P < or = 0.01) whereas fat mass decreased by 16.2 +/- 6.7% (P < or = 0.05). Changes in muscle strength ranged from -1.6-19.2%. Only hip adduction increased 19.2 +/- 9.5% (P < 0.05). Changes in bone density ranged from -1.3-5.2%, decreasing significantly at one site and increasing significantly at four of the nine sites measured (P < 0.05). Serum testosterone increased by 91.1 +/- 7.5% (P < 0.01), and testicular volume decreased by 24.0 +/- 3.2% (P < 0.01). Serum osteocalcin increased by 35.7 +/- 17.3% (P < 0.05), serum immunoreactive PTH (iPTH) increased by 41.4 +/- 15.1% (P < 0.05), serum calcium decreased by 2.3 +/- 1.0% (P < 0.05), and serum albumin decreased by 4.5 +/- 1.7% (P < 0.05). There were no detectable changes in fat-free mass, fat mass, muscle strength, or bone density in controls. The administration of testosterone enanthate in pharmacological doses for 6 months resulted in a modest reduction in fat mass and small increases in fat-free mass, muscle strength, and bone density. These changes do not support the use of androgens for enhancing athletic performance.

Comparison between testosterone enanthate-induced azoospermia and oligozoospermia in a male contraceptive study. I: Plasma luteinizing hormone, follicle stimulating hormone, testosterone, estradiol, and inhibin concentrations

Sex-steroid based male contraceptive regimes induce azoospermia in only 40-70% of Caucasian men. The reason(s) why the remainder maintains a low level of spermatogenesis (oligozoospermia) despite gonadotrophin suppression is unclear. In order to improve our understanding of this phenomenon, we examined the changes in sperm density and plasma LH, FSH, testosterone (T), oestradiol (E2), and inhibin (IN) in 28 normal men who received 200 mg testosterone enanthate (TE) im weekly during a male contraceptive efficacy trial. Gonadotrophins were measured by an ultrasensitive time-resolved immunofluorometric assay (DELFIA) with a sensitivity of 0.04 U/L, to determine the adequacy of suppression. Seventeen of the 28 men achieved azoospermia; the other 11 remained oligozoospermic (sperm density 3.3-4.7 x 10(6)/mL) after 6 months of TE exposure. Azoospermic subjects displayed a more rapid decline in sperm density, a significant difference being apparent by 5 weeks after starting TE. During TE treatment, both LH and FSH were consistently suppressed to below the limits of detection, whereas there was a 2.5-fold rise in T and E2 with a similar decrease in IN. There were no consistent differences in any of these hormone concentrations between the azoospermic and oligozoospermic groups. Recovery of sperm density to baseline levels or above 20 x 10(6)/mL was significantly slower in the azoospermic group. During the recovery phase, the azoospermic men exhibited significantly higher LH and FSH levels compared to baseline and to the oligozoospermic subjects even though no differences in circulating T, E2, or IN were observed. We conclude that incomplete gonadotrophin suppression or differences in sex steroid or inhibin levels are unlikely to be responsible for the maintenance of minor degrees of spermatogenesis in some men during TE administration. The rebound rise in gonadotrophins in azoospermic but not oligozoospermic responders during recovery may reflect a more profound degree of spermatogenic suppression in the former group.

Sperm motion parameters after suppression of spermatogenesis with a gonadotropin-releasing hormone antagonist plus testosterone supplementation

OBJECTIVE

To evaluate whether the chronic administration of a GnRH antagonist supplemented with T enanthate affects sperm motion parameters.

DESIGN

Prospective study.

SETTING

Academic medical research environment.

PATIENTS/PARTICIPANTS

Six normospermic men of reproductive age.

INTERVENTION

A 20-week treatment included the administration of 10 mg of GnRH antagonist every day and 25 mg of T enanthate once a week.

MAIN OUTCOME MEASURE

Computerized sperm motion analysis on each participant every 2 weeks for a period of 11 months.

RESULTS

Sperm concentration decreased after 4 weeks of the GnRH antagonist administration, accompanied by a reduction of sperm motility from an initial mean value of 56% to 34% on treatment week 4 and 21% on treatment week 6. In contrast, sperm velocity, linearity, amplitude of the lateral head displacement, and beat cross-frequency values did not significantly change in spite of reduced overall sperm concentration and motility. Azoospermia was reached within 6 to 12 weeks of the GnRH administration, and it was sustained during the treatment period. During recovery of spermatogenesis, sperm movement parameters returned to initial values earlier than sperm concentration and normal morphology. All participants recovered initial semen parameters 20 weeks after the end of treatment.

CONCLUSION

The administration of a GnRH antagonist supplemented with T enanthate successfully induced reversible suppression of spermatogenesis. The sperm motion characteristics appeared to be the last parameters to decline and the first to return to initial values after the treatment.

Development of copper male contraceptive. Contribution of India

In this review article the author discusses the possibility of making a male contraceptive with the inclusion of copper. The contributions made by different groups of workers in India towards this, are critically analysed. Aspermatogenic status of copper is recognised. The toxicity of copper on tissue is a great concern for continuation of this programme. Recently a hypothesis for slow delivery system of copper for functioning as aspermatogenic and spermatostatic was mooted. The veracity of the proposal is yet to be seen.

Suppression of human spermatogenesis by testosterone implants

Hormonally induced azoospermia is an effective, reversible form of male contraception; however, some men treated with weekly im testosterone enanthate (TE) injections fail to become azoospermic. As weekly injections cause widely fluctuating and supraphysiological testosterone levels, we tested the hypothesis that more stable, physiological testosterone levels would consistently produce azoospermia. Using a depot testosterone formulation which provides stable, physiological range testosterone levels for up to 6 months, we studied nine men before and after insertion of six 200 mg testosterone implants under the abdominal wall skin and compared the results with 38 men treated in a previous study with weekly im injections of 200 mg TE. Testosterone implants suppressed sperm output to near-azoospermia between the second to fourth postimplant months returning to normal by the sixth postimplant month. The fall in sperm output at the first month was greater after testosterone implants than TE injections (58% vs. 17%, P = 0.011) but similar proportions of men became azoospermic (5/9 vs. 25/38) or severely oligozoospermic (< 1 million/ml; 9/9 vs. 37/38). Plasma testosterone and estradiol levels remained mostly within the eugonadal range after implants but were markedly supraphysiological during TE injections. Both treatments suppressed immunoreactive LH and FSH to undetectable levels by ultrasensitive fluoroimmunoassay. Sex hormone-binding globulin levels were decreased and PRL levels increased by TE injections but neither was changed by testosterone implants. Prostate-specific antigen demonstrated a small rise of marginal significance (P = 0.065) after testosterone implants. Fewer men experienced acne after implants (0/9 vs. 25/38, p = 0.0004). Therefore a depot testosterone preparation with quasi-zero-order release demonstrates higher dose efficiency with similar (but not uniform) efficacy at inducing azoospermia but may cause fewer androgenic side-effects than weekly TE injections.

Developments in the control of testicular function

Clinicians and clinical investigators have developed improved means for controlling testicular function in men. New and refined approaches for stimulation and inhibition of the hypothalamic-pituitary-testicular axis are now available. This chapter reviewed the most successful ways to inhibit the reproductive axis in men and its current application to the treatment of precocious puberty, metastatic prostate cancer, benign prostate hyperplasia and as prospective male contraceptives. Safe, effective and reversible medical approaches to male contraception are now approaching reality. Azoospermia and severe oligozoo/azoospermia can now be accomplished in the majority of men with combined GnRH antagonists and replacement doses of testosterone. Androgens and androgen-progestogen concentrations will induce azoospermia in over 90% of Asian men and azoospermia or severe oligospermia in Caucasian ethnic groups. Field trials are ongoing to determine whether testosterone administration will be more effective than condoms as contraceptives. True precocious puberty can now be managed more effectively than in the past by suppression of gonadotropin secretion with GnRH analogues. Precocious puberty due to other causes can be treated more effectively with inhibitors of steroidogenesis and blockers of androgen action. Metastatic prostate cancer, previously treatable with either castration or oestrogens, is now amenable to suppression of androgen secretion. GnRH analogues are given either alone or combined with blockers of androgen action. While significant palliative effects are observed with endocrine ablative therapy in most men with Stage C or D prostate cancer, modest increases in duration of survival may be seen. Benign prostate hyperplasia was previously approachable only with surgical intervention. Recent data have suggested that medical treatment with 5 alpha-reductase inhibitors and/or selective alpha-adrenergic blockers may offer non-surgical alternatives in some patients. More data are needed to determine the role of medical management of this common disorder.

Depot gonadotropin-releasing hormone agonist blunts the androgen-induced suppression of spermatogenesis in a clinical trial of male contraception

Thus far, when tested as male contraceptives, GnRH agonists in combination with androgens were not very effective in producing azoospermia. Since in previous studies androgens were always given simultaneously with the GnRH agonist or later, we tested whether GnRH agonist administration after an initial androgen suppression phase might yield better results. After a control period, 3 groups of young healthy men (n = 8/group) received an initial loading dose of 400 mg 19-nortestosterone hexyloxyphenylpropionate (19NT-HPP), followed by 200 mg of the ester every 3 weeks for 24 weeks. One week after the first 19NT-HPP injection, 2 groups were given a single sc implant injection of 3.3 or 6.6 mg of the GnRH agonist buserelin, respectively, whereas a placebo implant was given to the third group. In the group receiving only 19NT-HPP, serum LH and FSH were markedly suppressed and remained low during the treatment phase. In the 16 volunteers receiving the buserelin implant LH and FSH were also suppressed on day 7, followed by a marked increase in the gonadotropins up to 2 weeks after buserelin implant injection. While LH was consistently suppressed for the remaining treatment phase, FSH returned to almost normal values in weeks 9-15. In contrast to the group treated with 19NT-HPP alone, in which sperm concentrations were reduced to oligozoospermia after only 3 weeks of treatment, the first suppressive effect in the 19NT-HPP/buserelin-treated groups was not seen before week 9. After 30 weeks, when the maximal suppression of spermatogenesis was seen, 4 of 8 volunteers in the group treated with 19NT-HPP alone were azoospermic, and the remaining 4 volunteers were oligozoospermic. In the groups treated with 19NT-HPP/buserelin, no more than 4 of 16 volunteers were azoospermic, and no more than 8 of 16 volunteers were oligozoospermic at any time point. It is concluded that GnRH agonist depot preparations have a blunting effect on the suppression of pituitary and testicular function caused by androgens in men participating in contraceptive trials.

Antispermatogenic effects of tolnidamine in langur (Presbytis entellus)

Tolnidamine (50 mg/kg body weight; twice a week; oral) was administered for 90 days to adult male langur monkeys (Presbytis entellus entellus Dufresne) to assess its contraceptive potential. Semen weight, volume, seminal fluid volume, colour, pH and libido remained unchanged. Sperm motility, vitality and morphology were impaired with the advancement of treatment. Sperm density reduced to severe oligospermia following 75-90 days of treatment. Increased number of immature germ cells were also noticed. Resumption of changes to pretreatment range was observed following 90 days of cessation of treatment. However, sperm density remained low all through the recovery period of 150 days. Seminal fructose, ACP, LDH and citric acid concentrations did not change markedly. A significant depletion in GPC and magnesium levels was recorded during treatment and early recovery periods. Alterations in germ cells and Sertoli cells were also observed. A progressive but reversible rise in serum creatinine was evident. Other clinical parameters and body weight response revealed no drug-related alterations. In conclusion, tolnidamine medication induced irreversible inhibition of spermatogenesis.

Effects of chronic testosterone administration in normal men: safety and efficacy of high dosage testosterone and parallel dose-dependent suppression of luteinizing hormone, follicle-stimulating hormone, and sperm production

In normal men, chronic testosterone (T) administration results in negative feedback suppression of gonadotropin and sperm production. However, azoospermia is achieved in only 50-70% of men treated with high dosages of T. Furthermore, the relative sensitivity of LH and FSH secretion to chronic administration of more physiological dosages of T is unclear. We determined whether a T dosage higher than those previously given would be more or less effective in suppressing spermatogenesis and whether, within the physiological range, T would exert a more selective effect on LH than on FSH secretion. After a 4- to 6-month control period, 51 normal men were randomly assigned to treatment groups (n = 9-12/group) receiving either sesame oil (1 mL) or T enanthate (25, 50, 100, or 300 mg, im) weekly for 6 months. Monthly LH and FSH levels by RIA and twice monthly sperm counts were determined. During treatment, T levels were measured daily between two weekly injections. Chronic T administration in physiological to moderately supraphysiological dosages resulted in parallel dose-dependent suppression of LH, FSH, and sperm production. T enanthate (50 mg/week) suppressed LH and FSH levels and sperm counts to 50% of those in placebo-treated men (ED50). T enanthate (300 mg/week), was no more effective than 100 mg/week in suppressing LH, FSH, and sperm production. Serum T levels in men who received 100 and 300 mg/week T enanthate were 1.5- and 3-fold higher than those in placebo-treated men, respectively. Except for mild truncal acne, weight gain, and increases in hematocrit, we detected no significant adverse health effects of chronic high dosage T administration. We conclude that 1) LH and FSH secretion are equally sensitive to the long term negative feedback effects of T administration; 2) sperm production is suppressed in parallel with the LH and FSH reductions induced by chronic T administration; and 3) even at the clearly supraphysiological dosage of 300 mg/week, T enanthate does not reliably induce azoospermia in normal men. However, there was also no evidence of a stimulatory effect of this T dosage on spermatogenesis. Furthermore, we found no evidence of major adverse health effects of T administered chronically even at the highest dosage.

Inhibition of spermatogenesis in men using various combinations of oral progestagens and percutaneous or oral androgens

Eight men (experiment 1) requesting male contraception received a daily oral dose of 20 mg medroxyprogesterone acetate (MPA) combined with 125 mg percutaneous dihydrotestosterone (DHT). Three months later the mean sperm count was only diminished slightly; the replacement of DHT for four men by percutaneous testosterone at the same concentration led to a dramatic fall in sperm count. For 6-18 months all men were treated with MPA plus percutaneous testosterone (250 mg daily). The latter dose restored physiological levels of plasma testosterone. Follicle-stimulating hormone levels were inhibited more severely than in the DHT-treated group, whereas LH levels were variable. Azoospermia was achieved and maintained in six cases; two men were oligozoospermic and in one case a moderate secondary rise in the sperm count was observed. Twelve volunteers (experiment 2) received a daily oral dose of either 5 or 10 mg norethisterone acetate plus percutaneous testosterone (250 mg daily). All of them achieved azoospermia within 2 months, but two subjects later exhibited a partial restoration in sperm count. Follicle-stimulating hormone and LH levels were inhibited more severely than in the first experiment. The sperm count and gonadotrophin levels returned to initial values within 6 months after cessation of the treatment in both experiments. No side-effects were noted concerning blood parameters, libido or body weight. However, several female partners had elevated levels of plasma testosterone. In experiment 3 (13 volunteers), percutaneous testosterone was replaced by oral testosterone undecanoate (160 mg daily). Only seven men were azoospermic and most of them had lowered levels of plasma testosterone. Thus, the combination of percutaneous testosterone and oral progestagens appears to be the most convenient for male hormonal contraception.

Male contraception

To share contraceptive measures between partners is a goal which should be reached in the future. The possibilities on the male side are still limited in comparison with the techniques available for women. During the last 20 years many efforts have been undertaken to study and evaluate possible methods for fertility control in the male, based on interaction with the hormonal axis, sperm maturation and sperm transport. The requirements for such a method in the male are the same as in female: high efficacy, little or almost no side-effects, high practicability and compliance and the possibility for easy reversibility in a high percentage of men. Despite their increasing acceptability worldwide, the existing male methods, condom and vasectomy, do not fully meet these requirements and therefore a search for alternative male methods is warranted. At present, the following medical approaches to male fertility control have been tested or are under consideration: (i) selective inhibition of FSH: antibodies, inhibin; (ii) inhibition of pituitary-gonadal axis: steroids such as testosterone, progestin-testosterone combinations, LHRH analogues with and without testosterone substitution; and (iii) selective inhibition of spermatogenesis by gossypol, a phenolic compound from cotton plant. Whether one of these methods will reach the desired goal for male fertility control has yet to be determined.

Clinical trial of 19-nortestosterone-hexoxyphenylpropionate (Anadur) for male fertility regulation

To test the effectiveness of 19-nortestosterone (19NT) as an antifertility agent, 12 normal men (age, 24.0 +/- 2.2 years) received 19NT-hexoxyphenylpropionate (19NT-HPP), 200 mg/week intramuscularly for 7 weeks. After this initial phase, two groups were formed that received injections at different intervals. Except for the 19NT serum levels, there was no difference in treatment effects between both groups. 19NT-HPP administration in general suppressed gonadotropins below detection limits, accompanied by testosterone levels well in the castrate range. At the end of the treatment phase, azoospermia or severe oligozoospermia (total sperm count less than 5 X 10(6)) was present in ten volunteers. No loss of libido or potency was reported. Administration of 19NT-HPP did not affect liver enzymes, creatinine, uric acid, serum electrolytes, or serum lipids. The presented data demonstrate that 19NT-HPP as a single entity given every 3 weeks can suppress sperm output in a high proportion of men and simultaneously maintain virility.