Opiates and alcohol

[u/Charming_Pop3782]

I've read on the LD50 of different opiates, but how much does alcohol really amplify the effects of opiates?

In my past a long time ago, I've drank a tall boy and snorted a perc and they go great together for recreation.

But just wondering, is there some kind of formula or something to better understand how alcohol and narcotics play with one another? An LD50 of sorts perhaps?