The use of medication for contraception is not just a privilege for women, but men can also achieve contraceptive effects by injecting a hormone. At present, the male contraceptive pill project studied by the Science and Technology Research Institute of the National Population and Family Planning Commission has entered the third phase of clinical trials. The researchers further found that the combined injection of testosterone undecanoate (TU) and progesterone every two months can more effectively inhibit spermatogenesis than the single injection of the former. If the combination medication is improved, the contraceptive validity period of a single injection of the medication is expected to be extended to 2-3 months.
Male contraception is more difficult than female contraception
The various contraceptive methods used by people mainly play a contraceptive effect by preventing the "meeting" of the germ cell of both sexes. The male hormonal contraceptives currently under development, like the female oral contraceptives, have the basic principle of inhibiting the production of germ cell within a certain period of time. However, from a technical perspective, inhibiting male sperm is much more difficult than inhibiting female eggs. Compared to adult women who can only ovulate one egg per fixed cycle per month, adult men can produce hundreds of millions of sperm per day without
It is periodic and difficult to control. Therefore, currently there are only four widely used male contraceptive methods: condoms, vas deferens, external ejaculation, and abstinence during the female menstrual cycle. The latter two are considered unsuitable for promotion by experts due to their difficulty in control and low safety factor. The difficulty of male contraception can be seen from this.
Testosterone undecanoate (TU) provides the possibility of reproducible contraception. Testosterone undecanoate is a long-acting male hormone preparation that was originally used for clinical treatment of male hypogonadism, but researchers later found that it can inhibit sperm production. It is reported that the research on male hormone contraceptives in China began in 1995. At that time, with the support of the World Health Organization and the National Family Planning Commission, the National Institute of Family Planning launched a phase I clinical trial of testosterone undecanoate. Subsequently, the research group selected 308 volunteers for the Phase II trial and received medication injections once a month. The vast majority of people have azoospermia or severe oligospermia in their semen examination, which has achieved the goal of effective contraception without affecting their sexual ability. After discontinuing the medication, the normal spermatogenic ability of all subjects was restored.
Normal fertility after discontinuation of medication
A physician from the Urology Department of the Third Affiliated Hospital of Peking University stated that research has shown that "testosterone undecanoate (TU)" provides the possibility for the development of male contraceptive pills that are injected every two months. However, they have also found that intramuscular injection of testosterone undecanoate alone cannot consistently and effectively inhibit sperm development. They selected 30 married healthy Chinese men aged 25-40 to participate in the experiment, and injected one group of subjects with testosterone undecanoate and a progesterone - long-acting medroxyprogesterone acetate - intramuscularly every 8 weeks. The results showed a significant inhibition of spermatogenesis, with a residual effect of up to 2 months after each injection.
The researchers believe that if testosterone undecanoate is dissolved in castor oil or used in combination with progesterone norethisterone, it can also have a longer medication interval, achieve a contraceptive effect of 2-3 months by a single injection, and facilitate male contraception. In addition, another advantage of the combination drug program is that after the drug is stopped, spermatogenesis returns to the original level, which will not affect normal fertility.
Why do male contraceptives use progesterone? It is reported that the hypothalamus, pituitary and gonad are responsible for controlling spermatogenesis, while progesterone is more effective than androgen in inhibiting hypothalamus. Tang Wenhao stated that in the study, it was found that individual participants experienced symptoms of breast development, which was symptomatic male hormone deficiency. Pairing progesterone with androgen can inhibit the hypothalamus and other effects, while the latter serves as a supplement or substitute for male hormones in the blood to avoid symptomatic male hormone deficiency.