My cat used to get bottles of Robitussin brand cough syrup, the plain kind with little ingredients aside from dextromethorphan
HBr and guaifenesin and a few dyes and stuff. Try and keep to the most clean stuff.
Robitussin brand gel caps (Cough Control, I think) I know has very little junk in them, they come in a bottle of 20 I think over all one bottle has 300mg DXM
HBr and no guaifenesin but a few dyes and stuff.
Either way, take the cleanest DXM product (syrups are easiest) and pour the fluid into a measuring cup. If using gel caps, break all the caps into the cup but syrup is easiest.
DXM extract TEK:
1) Fill measuring cup with cough syrup and add an equal volume of ammonia (the clear kind, no scents).If one adds too much, this is not an issue. I want to stress that for medicinal ingredients you want the syrup with NOTHING but DXM HBr and guaifenesin.
Blend the syrup and ammonia "emulsion" and let sit for 5m.
2) Add plain naphtha (ronsonal wick lighter fluid works well) in a ratio of 1/4 the volume of the ammonia/syrup emulsion. Some say a layer of naphtha one inch thick but a 1:4 ratio emulsion:naphtha works best, my cat finds.
Blend the solution for around 5m.
3) Take a ziploc freezer bag and pour solution into freezer bag. Pin the bag to a wall by its corner so that one corner of the bag is pointing down, kind of like a diamond.
Let the emulsions separate, should take about 10m-30m.
4) Once the layers have clearly separated, there should be a layer of colored emulsion on the bottom and a layer of clear emulsion on the top, cut a SMALL bit off the corner of the bag (with a cup underneath and a clean cup at hand) so that the bottom layer of the emulsion pours slowly into the cup.
Once the clear layer JUST starts to pour through -you want a bit to come through to make sure there is no color to the clear layer- one will then pinch the corner shut and take the other cup beneath it and pour the clear layer into that cup.
When the ammonia is added, the syrup's chemicals bond to the ammonia. When the naphtha is added, the DXM binds to the naphtha.
The layers separate and the bottom layer is ammonia with the guaifenesin and other junk bonded to it, the top layer is naphtha with DXM bonded to it.
5) If there is a bit of color or purplish foam or anything on the naphtha layer, add a bit more naphtha and let the bubbles settle and repeat the separation funnelling so that the naphtha is clean of any color.
Some people have reported success by adding water in after adding naphtha and the water should bind in with the ammonia and dilute it, they then siphon off the ammonia layer and add more water to the naphtha layer. The water should settle at the bottom and bind in with any ammonia, which should clean the naphtha layer up further.
6) When this has been completed, clean the measuring cup and pour the naphtha into it.
Take lemon extract (ReaLemon, etc. just like concentrated lemon juice extract) and add that to the solution.
Let sit for 5m or so, blending or agitating often.
7) Do the separation funnel method again to separate the layers. This time discard the naphtha layer and keep the lemon layer (the lemon will be the cloudy layer, the naphtha should stay clear).
Some people report a layer of foam or bubbles between the layers, if this is so, let it sit and the bubbles should go away. It could take a few hours.
8) When the lemon juice has been taken, boil it slowly for around an hour, this should remove any remaining organic solvents left behind.
The end product here is Agent Lemon which can be drank and it is relatively clean DXM. My cat recommends diluting it in juice or something because DXM is slightly caustic and gives a burning sensation also it is bitter and so is lemon extract so in short it just tastes very bad.
Another method involves, rather than adding lemon extract, evaporating the naphtha after it has been isolated. This will yield a freebase kind of DXM crystal which can be dissolved in water and drank or insufflated.
My cat has insufflated with success but does not recommend it because, once again, DXM is caustic and is easily the most unpleasant thing that she has ever snorted in her life (and she has snorted diphenhydramine
pills, mostly when she was on lorazepam
I assume that DXM can be administered rectally but once again that would probably burn a lot so oral ingestion is really the only way to do it.
Good luck. Check out Erowid.org for DXM extraction, it is full of methods. Maybe use the search engine next time. Thanks.