Why are there no popular birth control medications for men?

On this week’s episode of Show Me the Science, Professor Luke O’Neill explained the ongoing developments in contraception for men, as well as the many complications that scientists have come across along the way.

One of the most promising upcoming products still being tested is called ADAM.

“It’s a non-hormonal male contraception,” Prof O’Neill said.

“It’s a hydrogel that can be injected into the sperm duct, and then the sperm can’t get out, and hey presto, you can’t conceive a baby.

“It’s causing big excitement, because there’s no surgery, there’s no hormones involved, and those are the usual things that men use as a form of contraception, which can mean they’re not that keen on it, and it can be problematic.”

A man talks with a doctor in his office. Image: Bill Cheyrou / Alamy Stock Photo

Prof O’Neill explained that testosterone-based contraception for men can be particularly challenging to get right.

“Just like in women, progesterone actually in men can control sperm production,” he said.

“It does so by lowering a hormone called FSH, which stands for Follicle Stimulating Hormone.

“That is a hormone that will drive another hormone called LH, or Luteinizing hormone, that is made by Leydig cells.

“If you take progesterone, it represses all that.

“It stops the FSH production, that stops the LH, and that lowers testosterone, and now you decrease sperm production.”

Lower testosterone

However, Prof O’Neill said that lower levels of testosterone in men can cause symptoms such as lower libido and muscle strength.

As a result, products that do not use testosterone are more highly sought after, as surgical interventions such as vasectomies also have higher chances of complications.

“Another one that is a bit further down the track as well is called YCT-529,” Prof O’Neill said.

“It was discovered that vitamin A is involved in sperm production, and YCT-529 targets the vitamin A receptor and blocks it.

“Here’s the scenario; you’re taking vitamin A in your diet, it goes into your testes, it promotes sperm production.

“Now, you have a drug to block the vitamin A from locking onto its receptor to trigger the sperm to be made.”

According to Prof O’Neill, this drug wouldn’t be expected to have many side effects.

However, he said that all these products are still in the early stages of research, and are yet to be approved by any official body.

Main image: Luke O'Neill speaking on The Pat Kenny Show, 14-3-24. Image: Newstalk