How much 4-AD can be dissolved into 240ml of isopropyl alchohol? Is the 12g in Androsol the max. amount? If not, does the reason for limiting 4-AD to 12g have something to do with absorption efficacy?
Solubility of androstenediol in pure isopropanol is 0.4 g/mL. So 96g of androstenediol could be held in a 240mL solution. This is not to say that it would be beneficial. The absorption is based on drug per unit area. Increasing the amount of androstenediol in solution would therefore be a waste because the film produced on the skin would be caked on and only a certain amount per unit area will be absorbed anyway. This is why a light coat is applied with a fine mist sprayer over a large area. Bill could elaborate more on this and correct any mistakes I may have made. Hope this helps.
Yes, the most 4-AD you can get in short chain
alcohols (isopropyl, methanol, ethanol) is
around 50mg/ml give or take a mg.
John, I agree completely with all your analysis on why a higher concentration would not be desirable, but I can’t agree with the figure you give for solubility. Is it possible you obtained a literature figure for 5-androstenediol? It has a different solubility than 4-androstenediol does, and in the literature, “androstenediol” generally means
the 5-compound not the 4.
I don’t recall the figure I obtained by experiment for solubility at room temperature
but it was something like 70 or 80 mg/mL.
Androsol is 50 mg/mL both to achieve the
correct film thickness and also to avoid
crystallization of 4-AD if people’s houses
are cool, which would happen if you pushed
the solubility limits.
Not that this crystallization would be
a disaster – just warm the stuff back up to
room temperature and you’d be back where you
were – but people would probably freak out
from it. So it was fortuitous that the desired
50 mg/mL concentration was conservatively
under the solubility limit at room temperature.
Bill, you are correct. I just noticed my mistake, quickly looking in the Merck index. That value is for 5-androstenediol. Sorry for the confusion.