Hormonal contraception for men
Family planning with the help of a small pill - what was revolutionary and disreputable fifty years ago is now routine in many a woman's life. However, that could change in the coming years. Because current studies promise a new trend: reversible infertility for men - thanks to a special hormone cocktail. If a man wants to actively contribute to contraception for his partner, he currently has exactly two options to choose from – in addition to abstinence: the condom and vasectomy. However, both methods have their flaws. The condom, for example, is only partially safe; 12 out of 100 couples produce offspring unintentionally in the first year, despite proper use. The vasectomy, on the other hand, in which the man's vas deferens is severed by means of a simple surgical procedure and the ejaculate is thus cleaned of sperm, has the disadvantage that it can only be reversed to a limited extent.
Hormonal contraception, on the other hand, hopes scientists like Eberhard Nieschlag from the Institute for Reproductive Medicine at the University of Münster, could be both – safe to use and reversible afterwards.
The aim of hormonal treatment is to stop the production of sperm in the male body, spermatogenesis (azoospermia) or at least reduce it to a level sufficient for contraception (oligospermia). Three methods are currently the focus of research, each with varying degrees of success: the administration of androgens, a combination of androgen and progesterone, and the use of a gonadoliberin antagonist.
All three methods intervene in the hormone balance responsible for sperm production by influencing either the luteinizing (LH), the follicle stimulating (FSH) or the gandoliberin hormone. The former act on various cells of the testicle. While LH stimulates the Leydig cells of the testis to release testosterone, FSH - in cooperation with testosterone - causes the so-called Sertoli cells in the testicles to produce immature sperm. These then migrate through the seminiferous tubules of the testicle into the epididymis, where they develop into the final stage. The gonadoliberin, on the other hand, controls LH and FSH, and is therefore the top link for any hormonal contraceptive strategy.
The administration of androgens, the male gonad hormones, which also include testosterone, now tries to prevent the release of testosterone in the testicles by artificially increasing its concentration in the bloodstream. This reduces the production of LH and its stimulator gonadoliberin in a negative feedback loop, ultimately reducing the release of testosterone in the testicles. Since the artificial testosterone cannot reach the testicles from the bloodstream, the androgen concentration there remains too low to produce sperm.
However, this relatively simple method has a catch: not all men react equally to the excess testosterone. In Asian men, for example, sperm production is reduced by almost 100 percent. Only 60 percent of Caucasian men respond with oligozoospermia. They apparently need an additional active ingredient to keep their sperm in check. So while Asia is expecting a testosterone-based contraceptive as early as next year, the rest of the male world needs more research.
The use of gonadoliberin antagonists offers a relatively new approach here. They block the gonadoliberin receptors of the pituitary gland and thus prevent the release of LH and FSH and thus the production of sperm. This method works quickly and is safe. But there are problems here too – in terms of user-friendliness. Even with testosterone, neither pill form nor cream or plaster had proven to be practicable. Implants or - depending on the testosterone variant - injections every two to eight weeks are the rather unpleasant application options here. The gonadoliberin antagonists, on the other hand, require daily injections. In addition, their production is complicated and correspondingly expensive. The appeal of such a contraceptive method is therefore very limited.
Men owe a way out of this dilemma to women of all people – or rather to research into the contraceptive pill. Because it seems that a combination of testosterone and progesterone, which was initially the exclusive component of oral hormonal contraception, will make a breakthrough in the next few years. Here, progesterone prevents the release of LH and FSH, while testosterone, on the other hand, ensures that libido, muscle mass and mood are maintained - i.e. masculinity. This combination of active ingredients is currently being intensively researched: In Germany, a phase II study with 350 test persons has just been completed; other, much smaller studies have so far shown significantly better results than the use of testosterone alone. The first products are already expected in the next few years.
The question remains: does anyone even buy it? The pharmaceutical companies have at least expressed an interest – and have started to actively invest in research into the active ingredients. But they are not the only ones who see a market for male contraception - the World He alth Organization (WHO) has also been a firm supporter of the "pill" for men for years. After all, it would also be an effective option for population policy in cultures where, for various reasons, women do not have the opportunity to actively use contraception.
