Codeine High varies so much (?)

[Oxymadness]

I've come across an intriguing problem that i can't explain myself in any way.
So, the background is that I used to use Codeine Paracetamol Tablets from OTC to get a buzz. Usually around 300-380mg of Codeine after separating it.
I always used the generic formula's available because I am cheap.
Now I have moved country, and all I can find here are Solphadeine Brand ones. I've tried it again, but each time out of the 4 times just got me feeling sick and full of nausea for 3-4 hours until it gets lighter and a bit of the buzz comes through.
I know Generic vs Brand is not allowed until there is a good reason, but I find there very much is. The feelings are very very different, yet the make up of the medicines are the same.

Generic Formula : 500mg Paracetamol; 8mg Codeine Phosphate;
Solphadeine : 500mg Paracetamol; 8mg Codeine Phosphate;

I used to think it might be the caffeine, but with or without caffeine makes no difference to the nausea existing

Has anyone got the same expierence, maybe it's just solpahdeine ?

 

[Keif' Richards]

There should be no extremely noticeable difference here. You're dealing with a standard Cold Water Extraction and standard Codeine Sulphate, which would allow room still for variables like allergy to non-active constituents of the drug. Have you made comparisons in that regard?