Is there any way to predict solubility of a drug?

[TFSNIF]

I recently purchased and received some nifoxipam powder from a reputable vendor. When I received the drug I put it all (100mg) into 25mL of propylene glycol, hoping to make a 4mg/mL solution, but unfortunately it did not dissolve. I've shaken it and added heat and still there is plenty of drug floating in the bottom. I have made similar solutions using other benzos (etizolam, diclazepam) and they easily dissolved. I only just realized that the nifoxipam is sent as a HCl salt and both the other benzos I have experience with are sent as freebase.

So now I have 100mg nifoxipam HCl floating around in 25mL of PG and I would like to remedy that. My question is: since it's a HCl salt will it dissolve in water/ethanol - if I add 75mL of water or 75mL of vodka or some combination of the two would the drug be able to dissolve? My thought is that since PG is soluble in both water and alcohol I could add one or both of them and bring the final concentration from 4mg/mL to 1mg/mL, 100mg/100mL, but with 75mL that the drug can dissolve in.

This is assuming that since it is HCl it will dissolve in water or ethanol, but I don't know if that is right. Is there any way to predict what a drug is soluble in? Is there any way to predict how soluble something will be?

Does anybody have any suggestions of what I can do?

 

[TFSNIF]

Bump for visibility

 

[Pilll_head]

I'm a chemist and based on the structure of nifoxipam I would try straight vodka rather than water. You're not planning to ingest this are you? Propylene glycol isn't exactly good for you

 

[TFSNIF]

I will try straight vodka. I poured out almost all of the PG into a separate container and added 25 ml of water to the remaining drug/PG mix and it did not dissolve. Maybe it needs a lower concentration? I'll try it with the vodka first.

I was planning on ingesting it but at the concentration I was going for it would be 0.25-0.5 ml of PG 1-2 times a week. Given how common it is I didn't think it was especially harmful.

 

[szuko000]

Think of it this way, your (drug)HCl goes into solution to become (drug)+ and (HCl)- This is called dissociation and it is how salts behave in ionic solutions. You need something that is an ionic solution like water (H)+ (OH)- or your alcohol which I believe is (H)+ (alcohol)- Because of this you can dissolve it as well as the fact most alcohol has water in the solution to begin with.

Non-polar compounds get dissolved in solutions that do not support this action as they are unable to dissociate.

This is very simplified so much so that it may not be completely accurate it's been sometime since I though about basic inorganic