Brazilian researchers have started the clinical trial of a new medication for erectile dysfunction that contains molecules from the venom of a banana spider.

Brazil's Anvisa regulatory agency has allowed the second phase clinical trial of the ointment developed by biotech company Biozeus that is rubbed on the penis to make it hard.

Biozeus has bought the patent for the molecule in the banana spider's venom that triggers the release of nitric oxide, which is essential for an erection as it increases blood circulation and allows blood vessels to widen.

Federal University of Minas Gerais researcher Maria Elena de Lima, who is studying the venom for its molecule that triggers priapism or painful and persistent ED, said the medication can also be used to fight prostate cancer in men.

The study on the effects of banana spider bite or priapism began three decades ago. The condition inspired the development of a synthetic molecule using some properties of the spider's poison to create a gel to treat ED.

Covered in thick brown hair, and with a maximum size of up to 15 centimeters (six inches), the arachnid is one of the most poisonous in the world.