Your search found 6 Results
Lancet. 1996 Mar 23; 347(9004):830-1.The authors explain that Bonn's science and medicine report fails to do justice to recent advances in the search for effective, reversible contraceptive methods for men. Bonn refers to two World Health Organization sponsored clinical studies which established the contraceptive efficacy of hormone-induced azoospermia and severe oligozoospermia, and provided indirect information upon the characteristics and potential acceptability of such methods. Contrary to her supposition, there was no empirical evidence that the nine men in the first study who stopped taking testosterone injections before the full year of contraceptive efficacy did so due to increased aggressiveness. The potential for supraphysiological concentrations of testosterone to induce behavior or mood changes is, however, a genuine concern which needs to be addressed appropriately. Behavioral issues and acceptability to both partners are an important aspect of research into hormonal methods of male fertility regulation. The authors note that although currently available options for men are extremely limited, research into contraception for men is sadly underfunded and underresearched.
PROGRESS IN HUMAN REPRODUCTION RESEARCH. 1995; (33):2.Research results by the UNDP/UNFPA/WHO/World Bank Special Program in Human Reproduction published in 1990 showed that hormones can be used to reduce men's sperm levels to virtual infertility. Weekly injections of testosterone enanthate (TE) produced azoospermia in most men. A multicenter study was also completed in 1994 involving a total 399 men in nine countries who were given regular injections of TE. High contraceptive effectiveness resulted among those men whose sperm concentrations were reduced to 3 million or less per ml (oligozoospermia). The failure rate was 1.4 pregnancies per 100 person-years, similar to that of oral contraceptives. It took an average of 68 days to reach oligozoospermic and 100 days to reach azoospermic sperm counts after the 1st injection. To return to normal levels after the last injection took 112 days and 203 days, respectively, in oligozoospermic and azoospermic men. Testing of testosterone buciclate (TB) was also carried out in Germany to assess the effect of longer-acting androgen esters suppressing gonadotrophin secretion. Azoospermia was achieved in some men by giving a single dose of 1200 mg of TB, but at half that dose oligozoospermia was not reached. Research is also continuing into the male contraceptive effect of progestogen-androgen combinations. Progestogen prevents the production of sperm at much lower doses than androgen. Androgen is given to replace testosterone that is inhibited as a result of the suppression of gonadotrophin, but it is needed less frequently. The combination seems to suppress sperm production more quickly than the androgen alone. In China, India, and Indonesia, plans are prepared for efficacy studies with such combinations. The drawback for large-scale use is that the components have to be injected at different intervals. This may be overcome by combining TB with a progestogen with the same duration of action and giving both at the same time.
BRITISH MEDICAL BULLETIN. 1993 Jan; 49(1):210-21.The search for new, safe, effective, and reversible contraceptive methods for men as pursued by several agencies and probable future developments until the year 2000 is reviewed. A WHO consultation between vasectomy and the risk of cancer of the prostate or testis is unlikely and changes in family planning policies are unwarranted. Research in China has led to the ligation of the vas by percutaneous injection of sclerosing agents through a puncture opening. The suppression of secretion of either both luteinizing hormone and follicle-stimulating hormone (FSH) or of FSH alone; the recovery of circulating androgen to physiological levels; and the assessment of the functional capacity of residual sperm. Hormonal methods comprise the contraceptive efficacy of testosterone enanthate-induced azoospermia and oligozoospermia; and gonadotropin-releasing hormone analogue-androgen combinations. A large number of non-hormonal chemical agents lead to total spermatogenic arrest and to irreversible sterility. Gossypol was studied as an antifertility agent in clinical studies on more than 8000 Chinese men, but its use for contraception was halted owing to the high incidence of irreversibility and serious side effects such as hypokalemia. Among drugs and plant products for inhibition of sperm maturation, Chinese investigation showed that a multiglycoside extract of the plant Tripterygium wilfordii caused reductions in sperm motility and concentration in patients. A program established between Chinese, Thai, and UK centers aims to isolate pure compounds extracted from the plant for antifertility actions. In regard to contraceptive vaccines, passive or active immunization against FSH has resulted in significant decreases in sperm counts in macaque monkeys with inconsistent effects on fertility.
NETWORK. 1992 Aug; 13(1):20-3.Researchers are pursuing 2 approaches to developing a male contraceptive drug. 1 approach centers around suppression of sperm production the other around blocking conception. Researchers are looking at introducing hormonal contraceptives into men's bodies via injections or implants to stop sperm production. Both forms of these possible male contraceptives will not be available for many years, however. A WHO study on testosterone enanthate of men in 7 countries reveals total suppression of sperm production occurred in almost all the Asian men, but only about 60% suppression occurred in other ethnic groups. A current WHO study is examining whether a hormonal contraceptive which is not 100% effective can be useful if it would be more effective than barrier methods. The Population Council is conducting research on 2 capsule implants with 1 capsule releasing luteinizing hormone releasing hormone 13 to halt sperm production while the other releases an androgen to maintain sex drive. Animal tests indicate complete contraception with no side effects. The other possible means of suppressing sperm production is administration of a cottonseed oil extract called gossypol which appears to stop sperm production thereby eliminating the need for concurrent androgen administration. Yet it does cause potassium depletion in some men which can result in arrhythmias. An antifertility vaccine comprises the 2nd approach. Several US researchers are exploring an antifertility vaccine to produce antibodies only to the specialized sperm surface needed to attach to the egg. The 1st antifertility vaccine would probably be in pill form and a woman's contraceptive since it is earlier to target the smaller number of sperm in the oviduct than in the testes.
MEDICAL JOURNAL OF AUSTRALIA. 1991 Feb 18; 154(4):230-3.The 1st published study of efficacy of a hormonal male contraceptive, by the WHO Special Programme of Research, Development and Research Training in Human Reproduction, employed weekly deep intramuscular injections of testosterone enanthate. 271 fertile married men at 10 centers worldwide participated for 18 months. The goal of this preliminary study was to determine if azoospermia was necessary or sufficient for effective contraception. Azoospermia was produced in 157 men, who then participated in a 12-month trial. There was 1 pregnancy, for a failure rate of 0.8 per 100 person-years, highly effective in comparison with oral contraceptives, IUDs and injectables. There was a 12% annual discontinuation rate reasons cited were acne (4%), behavioral effects such as aggression or increased libido (1%), and other medical reasons (1%), e.g. weight gain, polycythemia, hyperlipidemia or hypertension. Recruitment of study subjects was difficult in developed countries until direct public appeals met with success. Future developments in the male hormonal contraceptive field will require a more acceptable administration route. To develop this, longer-acting injectables or implants utilizing testosterone cybutanate (20AET-1), or other combinations of testosterone with a progestin or a gonadotropin-releasing hormone antagonist are envisioned. The effect of incomplete azoospermia and the fertilizing capacity of remaining sperm is a serious issue for research. Each more crucial is resolution of the social, political and legal problems involved in male hormonal contraceptive research. Probably reform of the US product liability litigation procedures will do more to advance contraceptive development than any other single factor.
Potential long-acting contraceptive agents: esters and ethers of testosterone with alpha- and/or beta-chain branching.
STEROIDS. 1985 Dec; 46(6):947-53.A chemical synthesis program was established by the World Health Organization in 1975 with the primary goal of identifying long-acting male and female steroidal contraceptive agents. During the period 1977-80, 3 participating laboratories synthesized 12 related potential long-acting male contraceptive steroid esters, all derivatives of testosterone. 2 of the compounds were alpha-monosubstituted esters, 6 were alpha, alpha'-disubstituted esters, and 1 was a beta,beta'-disubstituted ester. Another 1 was a ditestosterone ester that was both alpha-monosubstituted and alpha, alpha'-disubstituted. 2 siloxy esters of testosterone were included for comparison given their similar alkyl substitution patterns. Testosterone 2-methyl propanate was prepared through use of the conventional method of reacting 2-methyl propanol chloride with testosterone in the presence of pyridine. For the esterification of the 17-OH group in testosterone with 3,3-dimethyl butanoic and 2-ethyl butanoic acids, the benzenesulfonyl chloride method was employed. This article sets forth the analytical, physical, and spectroscopic data for all the compounds synthesized and submitted for bioassay.