What is ouabain? The arrow poison that could be a new male contraceptive

Other than condoms, the options for men who want to prevent their partners getting pregnant are limited. But a new study suggests that an oral contraceptive derived from a poison used on arrowheads in the African jungle could soon be available.

Scientists who investigated whether a plant extract called ouabain could be used to create an oral male contraceptive pill found promising results.

Ouabain is present in two east African plants: Acokanthera schimperi and Strophanthus gratus. Mammals also produce ouabain at lower levels to keep blood pressure steady.

Traditionally, hunters and warriors used it because of its ability to stop the heart in the target.

In 1859, English botanist Thomas Kirk noticed that it caused cardiac action when he accidentally used a toothbrush contaminated with it. It was later used to treat heart conditions, according to Research Gate.

Because of its powerful properties, it is now a controlled substance. Drugs containing ouabain are prescribed in small doses to treat heart attack patients.

It works by inhibiting a membrane pump in animal cells. Some of the proteins it effects are found in cardiac tissue but one has been found in sperm cells and is vital to fertility in male mice.

Concerns about potential side effects on the heart have stopped it from being prescribed as a contraceptive so scientists have looked instead at creating a drug using ouabain that targets the protein in sperm specifically, and not the heart. When tested on rats, researchers found ouabain hampered the sperm's ability to swim but that it was reversible.

They hope this means that men can take a pill containing ouabain and restore their fertility when they stop, in a similar way to how the female contraceptive pill works.

The study published in the ACS' Journal of Medicinal Chemistry is the latest bid to revolutionise contraceptives for men. Last year, researchers announced plans to test a gel that prevents the production of sperm when it is rubbed into skin.