Can i use oxycodone acetaminophen 5-325 so i can try anal sex? i don't want that pain of the head entering the anal openning.

Probably: But i would think the best way to approach this is to google anal sex and see what the experts say. If that fails my fallback suggestion would be plenty of lube and take it verrrrrry slowwwly.

Review your options: Acetaminophen will not help. Pain can be caused by local pathology, lack of lubrication or incomparable size or lack of the experience. Sexual activities should bring pleasure not pain. Talk to your partner to find solution which you both accept.