i just read a sci-fi book about the first man to be "rejuvinated" when he was like 70 or so, he gets a treatment to reverse his physical body to that of a 20 year old. he has an increased sex drive, but he's dating a really hot, young girl, so he uses his "synthesizer" (can make most any drug, at your house - kinda like a molecular 3D printer) to make viagra a couple times