[quote]Bill Roberts wrote:
I don’t know of anything that is painful when it is at a concentration no greater than what dissolves simply in vegetable oil.
As concentrations go higher, sometimes preparations are painful. At least sometimes this is due to the amount of solubility enhancer used: for example, too much BA will be painful in its own right.
However at least in some instances it seems that that cannot be it: the carrier is non-painful, but some high concentrations – well beyond what would dissolve simply in vegatable oil – of an added steroid are painful.
This has me thinking that it is not likely really the steroid itself that is painful, as if so then it ought to be at least a little painful at the more modest concentration, but rather that the situation where its being solubilized depends on these enhancers is what causes the problem.
For example, let’s say a non-painful amount of BA is used.
Well here’s the thing: BA is water soluble. So after injection, the BA undoubtedly diffuses out and is carried away, leaving the steroid now supersaturated in the oil. It may well crystallize, leading to the pain.
While benzyl benzoate has low water solubility, it does have some (whereas by comparison vegetable oil has essentially zero and the steroid ester also has extremely low water solubility) so the same thing could occur there as well.
Just thoughts on it, not proven fact that this is why, for example, TP in vegetable oil at 50 mg/mL is painless whereas solubility-enhanced 100 mg/mL preparations are generally or perhaps always painful.
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Thank you Bill. Very nice explanation. I take it you use the former variety, ie;TP in veg oil?
Is there anything special about brewing that up?
