Lots in the news about the male pill over the last few weeks.
This is great after a study was stopped a couple of years ago because of side effects that were very similar to those experienced by women on hormonal contraception.
Male contraceptives contain testosterone and progestagen. They work like this:
You need a hormone called FSH (follicle stimulating hormone) to start sperm production in the testes. FSH is produced in the brain and travels in the blood stream to the testes. in the testes it stimulates the production of both sperm and the male hormone testosterone. The testosterone has a negative feedback effect on FSH so it stops more sperm and testosterone production until the levels start to fall again - that way a fairly constant level of testosterone is maintained in the blood and sperm are produced regularly.
What progestagen does is it stops the production of FSH - that way there is no sperm production and no testosterone production. Thats fine except that men need testosterone to maintain their male sexual characteristics (male patterns of hair growth, lean body mass etc). So they add back the testosterone. That is why the male pill/gel/injection contains two hormones - progestagen and testosterone.
It will be great to expand contraceptive choice in this way.
Problem is that it is going to take 10 years to do the studies until then vasectomy and condoms are the only options…