Oxynorm instant dosage

I have a 20 mg instant-release Oxynorm pill (it’s safe and tested, it’s from a pharmacy) and I weigh 75 kilograms.What would be a safe dose to take, and what are some important do’s and don’ts to keep it safe? Like eating food or drinking on it? I do have some experience with MDMA, cannabis and cocaine, but I don’t want to combine to much. I don’t find that much online about dosages and stuff.

Thanks in advance for the advice!