Drugs that create erections have been developed, but they need to be injected into the penis before intercourse. One drug, papavarine, can cause prolonged erections.
The new substance, called Stearyl-VIP, is capable of crossing the skin and entering the blood vessels and has worked on castrated rats.
According to the latest edition of New Scientist magazine, health authorities in Israel are now considering starting the first human trials of the lotion. No side-effects were found in the rats.
Stearyl-VIP is a compound comprising a vasoactive peptide (VIP), a fragment of protein and a stearic or fatty acid. VIP was identified 10 years ago as a natural agent in penile erections.
The researchers warn that their salve is not a cure-all. Impotence has a variety of causes, both physical and psychological, and they believe that Stearyl-VIP may be useful for men, including diabetes sufferers, who have low levels of VIP.
The research has been funded by a Japanese company, Fujimoto Pharmaceuticals, which plans to develop it for use in the Far East.