Greater solubility of substances in low pH solutions?

[jasoncrest]

I've been using Buprenorphine for years now, intraveinously.
In the begining I used sterilized water (pH = 0). After many months the Bupe had not any effect on me anymore...

One day I decided to use a 0,9% Sodium Chloride solution as the liquid I would use for injection.

I prepared the shot, and to my surprise, I really felt a narcotic effect; it was the same the second and third time I used Sodium Chloride; then I got used to it, and I didn't feel the effect anymore...

Buprenorphine is only slightly soluble in water (17mg/mL); is it more soluble in a Sodium Chloride solution?

Is the pH responsible of that? (the sodium chloride solution has a pH between 4 and 7 -> acidic, sterilized water has a pH of 7 -> neutral)

Can the pH have an influence on the solubility of a substance in water?

 

[Pct]

The sodium chloride doesn't change the pH of the solution. 0.9% NaCl solution isotonic with blood plasma, which is why its better to inject with that solution.

 

[BilZ0r]

Sterilized water has a pH around 7.

Sodium Chloride doesn't effect the pH of a solution by any great amount.

But yes, the pH of a solution can massively change the solubility of a substance.

 

[fastandbulbous]

In the begining I used sterilized water (pH = 0).

pH0 = concentrated acid soln..

pH is 1/(log[H+]), which for pure water is 7 (as BilZ0r has pointed out). Sodium chloride can decrease the solubility of hydrochloride salts by a small amount, but not anything worth bothering about with a drug as potent as buprenorphine

 

[jasoncrest]

yeah I meant sterilized water pH=7.

On the bottle of Sodium Chloride it says "pH = 4,5 - 7,0" so it is acidic, no?

Thanks for the replies.

 

[brainiacthemaniac]

From what I understand, the lower the PH, the more hypophilic it becomes, thus allowing for a polar substituent to be added to the lipophilic molecule and ultimately allowing for the oxidation-conjugation process. i.e. (-OH) hydroxyl group, added to be the functional group to create glucruonic acid, a highly polar molecule, however pharmacologially inactive.

 

[BilZ0r]

On the bottle of Sodium Chloride it says "pH = 4,5 - 7,0" so it is acidic, no?

It's probably just that it is really poor quality I would geuss, and so it might be acidic (they probably extract it from sea water, they same way the produce HCl and NaOH)