Hello !
Concerning the dissolution testing, I don't understand why we work in NON-SINK conditions when doing development (for example if I test the solubility of my active ingredient) and in SINK conditions when we have to do regulation...
Thanks !
I am not a specialist in regulatory dissolution, others may have more insight, but I think sink conditions are used to favour better reproducibility.
When determining thermodynamic solubility on the other hand you need to reach equilibrium.
My interest is more in more with biorelevant dissolution. This can be more relevant to development than QC methods. These will not necessarily be in sink conditions, as drug products may not find themselves in sink conditions for very long in real life. It is informative to follow dissolution to see if it reaches saturation. Of particular interest is possible over-saturation, in which case it is important to establish how long over-saturation lasts (the "spring and parachute").
SINK avoids reaching saturation point. For regulation in pharma circles, one wants to avoid concentrations of the drug reaching close to saturation point as cooperative accumulation leads to increased precipitation at higher concentrations.
Thomas Nicol Patrice Larger Thank you for your answers !
But the purpose of maintaining SINK conditions in the quality control of pharmaceuticals products is mainly to quantify the active ingredient (because if we have saturation, we can't quantify well)?
If so, why?
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