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 contraceptives
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.
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.