The idea of a pill that a man could take to temporarily “turn off” his sperm for worry-free sex on demand may sound more like science fiction than real, hard science, but it’s the goal of new research on male contraception that is well underway. A team of researchers funded by the National Institutes of Health has developed a compound that can temporarily “deactivate” sperm by inhibiting an enzyme called sAC, which is necessary for sperm to be able to swim. When sAC is deactivated, the theory goes, it’s impossible for sperm to make the long arduous journey to the fallopian tubes to fertilize an egg. Many have lauded this compound as a breakthrough in the world of male contraception, and envision a future where men can take on the burden of preventing unintended pregnancy. But the better question might be, will men want to? Read on to find out why we’re dubious about whether this “off switch” for sperm would actually be effective, and why even if it is, men still may not want to use it.
So, what exactly is the “off switch” for sperm?
The “off switch” for sperm is sAC, which stands for soluble adenylyl cyclase. sAC is an enzyme present in most cells and important in cellular regulation and cell signaling. As is typical in the immensely complex field of cellular biology, the many functions of sAC are not fully known, but it seems to play an important role in ion transport in the kidney, regulating fluid in the eye, neuron development, immune response, digestion, and placenta development, in addition to proper sperm development in males.
People with mutations that affect their production of sAC have difficulty with calcium regulation and thus develop kidney stones more easily, and exhibit poor bone density. Furthermore, sAC interacts with CFTR, an important ion transport protein that is especially crucial to proper functioning of the airways and the pancreas. However, while men with a natural mutation that prohibits them from producing sAC are infertile, they are otherwise seemingly healthy (besides, again, that pesky issue with kidney stones).
Inhibiting sAC stops sperm movement
A key to the sAC inhibitor proposed for use as male contraception, TDI-11861 (a very catchy name, we know), is that it breaks down after a few hours, after which sperm has been shown to regain normal function. As elaborated by the research team, since this compound can take effect within an hour, men can take it on an as-needed basis rather than having to take it every day, as is the case with hormonal birth control options. Because the body is only exposed to the compound for a few hours at a time, presumably the other cells that rely on sAC for different mechanisms will not be greatly impacted, though this is a big assumption to make and requires further study.
Right now the compound has proven successful in mice, will next be tested in rabbits, and theoretically will eventually move on to human trials (perhaps by 2025, which is the researcher’s stated goal). Mice are a common starting point for drug development and testing since they are genetically very similar to humans, grow to maturity quickly, are small and easy to house, and have been studied extensively. The rabbit is often used as a second test species in reproductive health studies as they are also small and inexpensive, their reproductive systems even more closely resemble that of humans, and semen is easy to obtain from rabbits [2]. Thus far, mice treated with TDI-11861 have not demonstrated side effects, even with continual treatment over a period of several weeks.
Are sAC inhibitors the future of male contraception?
As most folks already know, current contraceptive options for men are few: condoms and vasectomies. According to the Cleveland Clinic, the typical-use effectiveness rate of condoms is only about 87%. While vasectomies boast a higher effectiveness rate for preventing pregnancy, they carry more risks than people might think (including regret) and may exacerbate existing relationship issues, like lack of intimacy.
sAC inhibitors certainly have appeal for many as a non-hormonal, use-as-needed, quickly reversed contraception option for men, but they have a long way to go before potentially hitting pharmacy shelves. This compound has not yet started human trials, and it’s possible that side effects could be present in human subjects that were not observed in mice experiments, or that the compound could interact with other medications or health conditions that prevent certain men from being able to use it safely. There’s also reason to believe it might not work to prevent pregnancy all that effectively (more on this, below!).
The real reasons male contraception doesn’t exist yet
Aside from potential problems that could still arise in human testing, sAC inhibitors could meet the same fate as other male contraception. That’s right, sAC inhibitors are not the first development in male contraception, or even in highly effective non-hormonal male contraception.
In an illuminating article published by the BBC, Zaria Gorvett traced the hapless history of male contraceptive research and its various pitfalls. For example, researchers discovered a chemical compound that would allow men to orgasm without ejaculating, but many men found the so-called “clean sheets” pill “emasculating” and the project lost funding. Testosterone-based contraception is accompanied by side effects like acne, oily skin, and weight gain (side effects that women on birth control would likely scoff at), which consistently brings clinical trials for male contraceptives to a grinding halt (read more about birth control’s dubious path to FDA approval here).
Attempts to research male birth control are often derailed because of this lowered “hurdle of acceptability,” in terms of the risks and side effects men are willing to tolerate in order to prevent pregnancy, In other words, since men aren’t the ones who actually experience pregnancy, and since female birth control is already so widely accepted, even small risks can be seen as dealbreakers for men when it comes to considering a male contraceptive. Susan Walker, an associate professor of contraception and reproductive health at the UK’s Anglia Ruskin University, summed up for the BBC:
“I’m no longer optimistic [about the future of male contraception]. Each method seems to hit the hurdle of acceptability.”
Furthermore, the development of any new drug represents a significant investment on the part of the pharmaceutical company. It’s a big risk to develop a drug without being 100% certain that people will be interested in using that drug, and in fact, the BBC also cited a survey finding that only 20% of male respondents expressed interest in taking a male contraceptive pill.
Considering the fertile window
Finally, from where we sit here at Natural Womanhood, it’s unclear how effective TDI-11861 would be at preventing pregnancy for couples having sex inside the fertile window.
Consider this: we know that sperm can survive for up to five days inside the female reproductive tract in the presence of fertile cervical mucus, and we’re told that TDI-11861 wears off within hours—after which point sperm regain normal movement. If a man uses a TDI-11861 injection (or pill), and the couple then has sex, it seems there could still be a chance that pregnancy could occur, if those sperm have been able to survive the acidic environment of the vagina long enough to regain movement (which is theoretically possible while protected by the presence of alkaline cervical mucus). These sperm could then still make their way up through the fallopian tubes to await an egg, should sex occur in the days leading up to ovulation when fertile-type cervical mucus is present. One wonders if this is yet another instance of birth control research inadvertently validating the science of fertility awareness!
This brings us to the next point: In reality, all the talk of who in the relationship must singlehandedly bear the weight of contraceptive inconvenience, discomfort, or adverse effects is moot when a couple understands how their combined fertility works. Fertility Awareness Methods (FAMs) give couples this knowledge, and teach them how to use it to avoid or achieve pregnancy—without interfering with anyone’s body in any way. FAMs are egalitarian, effective, and free from any side effects.
Furthermore, FAMs can bring partners closer together in surprising ways. Additionally, since sperm counts appear to be significantly decreasing worldwide, one might question the logic of finding novel ways to inhibit healthy sperm. Even though sAC inhibitors aren’t expected to impact fertility long-term, hormonal birth control isn’t supposed to either, and yet there are ways it may impact future fertility, especially with long-term use.
The history of futile male contraception research raises questions about whether sAC inhibitors could ever achieve widespread acceptance, even if they do prove effective. Instead, men seeking to take on more responsibility for family planning in their relationships should look into FAM. Through knowledge and understanding of each partner’s natural patterns of fertility and infertility, couples can learn how to effectively avoid pregnancy, side effect-free.
References:
[1] Tresguerres M, Levin LR, Buck J. “Intracellular cAMP signaling by soluble adenylyl cyclase.” Kidney Int. vol 79, no. 12 (2011):pp. 1277-88. doi: 10.1038/ki.2011.95. Epub 2011 Apr 13. PMID: 21490586; PMCID: PMC3105178. [2] Foote RH, Carney, E W. “The rabbit as a model for reproductive and developmental toxicity studies” Reproductive Toxicology, vol. 14, iss. 6 (2000): pp. 477-93. ISSN 0890-6238,https://doi.org/10.1016/S0890-6238(00)00101-5.
Additional Reading:
The scoop on male birth control pills and gels
The reality of vasectomy risks and side effects
A vasectomy can’t repair a broken love life—and it might cut a relationship short
