As for the drugs, people should be careful since some folks may have cardio vascular issues that are unknown. Headaches are definitely a bad sign.
I know this because of the immunotherapy drugs for allergies due to having a horse farm. I found this out with the assistance of a doctor.
So be careful always .... you only have one life to live.
As for anal sex, I so want to try this with my partner.
I was also curious about this too, but honestly if I ever get the chance (current partner is a hell no), I want to feel the full process (lube of course).
Since my life experiences suck it would have to be pegging with a woman, or a transgender woman who was intact.
I mentally can't go there yet due to my rape with men even though I am pansexual.