An Analysis of the Different Types of New Forms of Male Contraceptives
By: Harper Wilkinson
Over the past several decades, the science community has worked towards the creation of efficient and safe male contraceptives. Not only is it responsible to have an alternative contraception that targets men, but male contraceptives can have fewer side-effects and can be more effective than ordinary birth-control (1). Male contraceptives can decrease unwanted pregnancies and the transfer of sexually transmitted diseases from sexual partners. At the moment, the only approved forms of male contraception are as follows: vasectomies, male condoms, and withdrawal (2). The current research in male contraception is divided into two sectors: hormonal and nonhormonal. Hormonal forms of birth control target the hormonal pathway in the body, decreasing testosterone and sperm production; this is similar to the pill in females. Nonhormonal contraception targets the production, structure, and function of sperm, specifically through the creation of proteins. Both can be effective and safe but work in dramatically different ways.
Hormonal Contraceptives
As of 2018, several hormonal male contraceptives are being studied in clinical trials. One example of this is Nestorone gel and a single application testosterone gel (3). Androgen, a type of sex hormone, alone can suppresses testicular testosterone production, and Nestorone gel uses a similar hormone to limit sperm production. When testosterone levels are suppressed to below a certain threshold, sperm production does not occur, thus causing an inability to conceive (2). However, there are downsides to using androgen and other hormones to suppress sperm production. Libido, erection, ejaculation, and muscle mass can be severely impacted. However, through a combination of hormone suppression and testosterone gel, desired sperm suppression could be reached, thus decreasing the negative side effects to a minimum. A recent study analyzed and researched the effects of intramuscular injections of long-lasting androgen, among other hormone suppressors (4). 320 couples participated, but the study was terminated early due to side effects such as: mood swings, depression, pain, and increased libido. However, at the time the study was ended, non-suppression rates were around 7.5%, and 75% reported that they would use the injection again (4). Hormonal contraceptives, like Nestorone gel or the use of androgen and testosterone together, can provide an efficient way to limit the amount of sperm produced, thus decreasing the chance for unwanted pregnancy and sexually transmitted disease.
Non-hormonal Male Contraception
Non-hormonal alternatives focus on suppressing testosterone production through proteins and by avoiding the hypothalamic-pituitary feedback loop that is used in hormonal medications. The proteins targeted affect sperm function and structure, making pregnancy virtually impossible. However, many non-hormonal men's birth controls are still in the preclinical phase, but the current research is important. For example, some drugs tried on primates and stallions targeted the release of immature spermatids in order to decrease the amount of mature sperm cells being ejected from the testicles. Full reversibility and no side effects were reported (1). Research is also investigating numerous ion channels that affect sperm mobility and motility. CatSper, a sperm-specific calcium ion channel, is required for male fertility, and through an in vitro study using a calcium ion channel inhibitor, male infertility in mice was achieved (1). This method was also reversible. Non-hormonal contraceptives provide an alternative route to hormonal contraceptives, targeting the proteins of sperm.
Other Alternatives
There are also a few other alternatives that are worthy to mention. One is silicone plugs. The plugs are composed of silicone and nylon tails that anchor the plugs to the vas-deferentia. This prevents sperm from entering the urethra, though a minor surgery, and it is also reversible (5). Finally, one of the most important devices, which is in Phase 3 clinical trials, is RISUG. Professor Guha, a scientist in India, noticed that when pipes were coated with a polymer called styrene maleic anhydride (SMA), it killed bacteria in the water (5). This discovery was translated to male birth control, for unwanted pregnancy was a big issue in India at the time. The water pipes were compared to the vas-deferentia, and the bacteria was compared to sperm. RISUG is a polymer that works the same way as SMA but is safe in the human body (5). Sperm traveling through the vas-deferentia to the urethra experience ionic and PH stress, causing them to be completely useless (5). A diagram of how RISUG is shown below:
Male birth control research is not new, but as science progresses, a possible device, drug, or hormone that is safe and effective is becoming more likely. While most non hormonal alternatives are still in preclinical trials, hormonal alternatives, and other interventions like RISUG, are already in clinical trials with the potential to dramatically diversify contraceptive use and prevent unintended pregnancy.
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P. Muttreja, S., R. Dereuddre, S., G. Shih, D., Brown, S., P. Kogan, M., J. Eberhardt, A., . . . M. Sax, E. (1970, January 01). RISUG® as a male CONTRACEPTIVE: Journey from bench to bedside. Retrieved March 05, 2021, from https://bacandrology.biomedcentral.com/articles/10.1186/s12610-020-0099-1