Like so much Western propaganda, this is evidence free. From Caitlin Johnstone at caitlinjohnstone.com:
The west is advancing the claim that Putin is distributing Viagra to his soldiers so that they can more effectively rape Ukrainians, which was a ridiculous propaganda narrative the first time the west used it to manufacture consent for regime change in Libya.
In a Thursday interview with the French government-owned news agency AFP, a Mauritian-British official from the United Nations named Pramila Patten claimed that Russia has a “military strategy” of mass rape in Ukraine and that Russian soldiers are being “equipped” with the erectile dysfunction medication Viagra in order to facilitate that military strategy.
“When you hear women testify about Russian soldiers equipped with Viagra, it’s clearly a military strategy,” Patten said.
Because AFP is one of the major propaganda multipliers whose material is republished by news media outlets around the world, Patten’s completely unevidenced claim of weaponized Viagra has been uncritically reported as a real news story by outlets like CNN, The New York Post, Forbes, The Independent, The Hill, and Yahoo News. This claim will now be folded into many rank-and-file mainstream news consumers’ understanding of what is happening in Ukraine, despite its brazenly propagandistic nature.