Codeine in Effervescent Powder

[Ale]

SWIM's got some small pharmaceutical sachets filled with a fine powder containing Codeine Phosphate 30mg + Paracetamol 500mg each. They might be thought as the ideal thing to get a CWE off of..due to the fact they come in a fine powder ready to dissolve..trouble is: the pharmaceutical specialty actually contains also a lil of NaHCO3 (bicarbonate of soda), beside some others neutral fillers, in order to give the powder effervescent properties and,as a consequence, to avoid its abuse by ppl or at least I suppose so..because besides..it makes sense.
Do any of you guys have any suggestions/hints about how to extract the Codeine out of them overcoming the NaHCO3-obstacle just in case it DOES consist into being one of course..and if you think it DOES..how would you treat this product in order to get the max amount of almost pure Codeine out of it? Thanks to you all from now cause I'm sure you'll help with your precious advices as you always do after all. =)