Outside of using condoms or being sterilised (vasectomy), birth control options for men remain scarce. This is mainly down to economics, but some keen players are developing contraceptives for men that are in various stages of clinical trials.
Research and trials of hormonal male contraceptives1–5
Progesterone affects sperm, and is high up on the list of ingredients in hormonal male contraceptives for this very reason. This is also why some sunscreen should be avoided in men – some ingredients are endocrine disruptors that can cause male infertility (at least temporarily) by making sperm do funny things.
A large-scale phase II trial of an injection containing progestogen (a substance that binds to and activates progesterone receptors) and testosterone, to suppress sperm production, was canned early because of adverse events. These side-effects included acne, weight changes, increased libido and mood disorders.
The trial lasted long enough to show that the injections were reversible and highly effective at preventing pregnancy. The safety committee’s two members were split on whether to stop early – one said yes and one said no, which meant the trial had to be stopped. The adverse effects were not particularly severe, and over time may have stabilised, as women do when taking contraceptives.
Another company were developing a contraceptive gel that was rubbed into the shoulders daily, with care being taken not to transfer the gel to others they come into contact with (children, a female partner). The gel is made up of testosterone and nesterone, a progestin (artificial progesterone), and was effective at suppressing sperm production in 89 per cent of the men who used it.
The next step is to see if the gel prevents pregnancy. A trial is planned for 400 couples across the globe. When sperm counts drop below 1 million/mL of semen, back-up contraception will cease.
Another study is examining an androgen (dimethandrolone undecanoate (DMAU)), for use in a male birth control pill and an injectable that lasts for a while. DMAU has suppressed sperm production in rabbits enough to suppress fertility, with fertility returning after pills or injections stopped. This pill has undergone a 28-day safety study, which has been a success.
What about non-hormonal approaches to male birth control?
Side-effects are a real issue with hormonal contraceptives for both men and women. A great deal of human resources goes to our fertility, so blocking this process has a lot of secondary effects that are at best unpleasant and at worst debilitating. Ultimately nobody should be on hormonal birth control, because it is disturbing to multiple body systems, rendering them unable to function as they were designed.
What this also means is that there are many targets in the fertility process that could be reached, including genes. One study, a device, is being developed that acts like a reversible vasectomy, Vasalgel. A polymer powder is dissolved in a solvent and injected into the vasa deferentia, and stays soft and gel-like, which allows water soluble molecules to pass through, but not sperm.
When a man wants to make a baby, another injection of sodium bicarbonate is injected to dissolve the polymer. This technique has provided effective contraception in rabbits and rhesus monkeys. A clinical trial is expected in 2018.
Why men are seeking reproductive control
Birth control options for men may be extremely popular – it gives men control over their fertility in a way that women have had available to them for some time, without the crappy side-effects, both obvious and not, of hormonal interference. The world has changed significantly in the past 50 years, both socially and with our ability to determine paternity by DNA testing, which is also a driver of men seeking fertility-control options.
Socially, casual sex, pairing up later, and having babies later have all contributed to changes in attitudes towards sex, which means there are more opportunities for unwanted pregnancies than ever.
Social change still hasn’t taken into consideration the significant disadvantage men experience due to largely having to rely on the honesty and reliability of their female partners in taking hormonal birth control. Condoms, while effective, are not popular. We can all see the benefits, but putting condoms to good use depends on many factors. Catching chlamydia is a bit different to getting someone pregnant if you are sloppy with condom use.
The economics of male contraception
Economics are the main reason large pharmaceutical companies appear to be disinterested in developing male contraceptives. Drug-makers don’t think contraceptives are that exciting in dollar terms, unlike, for example, a blockbuster like Pfizer’s cholesterol-lowering drug atorvastatin, which clocked up over $100 billion in less than 15 years.
Male contraceptives would need to be at least as effective as the pill for women (about 91 per cent when used like a normal person, including being forgetful).
Additionally, because the birth control pill for women has been in production for so long, there are now cheap generic brands, meaning that the first pharmaceutical company to develop a birth control option for men would be charging a premium to cover research and development costs – which men might not be willing to pay.
Legal issues can also be a problem when it comes to contraceptives, with safety a prime concern. Because contraceptives are not curing a disease, but modifying a normal biological process, the risk of side-effects and adverse outcomes is higher, in both men and women. These side-effects can be subtle and easy to ignore in women, with fluctuating hormones and their physical and emotional outcomes a normal part of the menstrual cycle, but harder to ignore in men.
Non-governmental organisations are on the case, but they don’t have the funds to do large clinical trials that are required by the FDA, but if other organisations can do the preliminary phases of trials, a larger manufacturer might step in and complete the rest.
This means partnerships are required. One organisation, the NICHD, spends US$20-24 million every year on contraceptives research, with the funds split evenly between male and female methods, however, this organisation has no end-game in marketing and selling drugs, unlike pharmaceutical companies.
References
- 1.Reynolds-Wright JJ, Anderson RA. Male contraception: where are we going and where have we been? BMJ Sex Reprod Health. Published online September 19, 2019:236-242. doi:10.1136/bmjsrh-2019-200395
- 2.Page ST, Amory JK, Bremner WJ. Advances in Male Contraception. Endocrine Reviews. Published online April 24, 2008:465-493. doi:10.1210/er.2007-0041
- 3.Amory JK. Progress and prospects in male hormonal contraception. Current Opinion in Endocrinology, Diabetes and Obesity. Published online June 2008:255-260. doi:10.1097/med.0b013e3282fcc30d
- 4.Gava G, Meriggiola MC. Update on male hormonal contraception. Therapeutic Advances in Endocrinology. Published online January 2019:204201881983484. doi:10.1177/2042018819834846
- 5.Mathew V, Bantwal G. Male contraception. Indian J Endocr Metab. Published online 2012:910. doi:10.4103/2230-8210.102991
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