ALA, R-ALA or K-R-ALA for skin?

[orangehrzn]

Dr. Todorov, which is better as a topical for skin applications?

The regular ALA (50/50 mixture of S- and R- isomers),
the R-ALA or the pottasium salt K-R-ALA?

Please consider effectiveness, bioavailability as well as stability.

[drtodorov]

Here's some points to consider:

In vitro and perhaps some in vivo studies unrelated to skin indicate that R-ALA is better for carb metabolism, mitochondrial respiration, etc; but I have not seen any head to head comparison specifically for the skin. It is unlikely that R-ALA is worse for the skin that racemate, so it is either the same or better - but there are no data to be certain which.

In the solution ALA ionisation form depends on the pH rarther that on whether you initially dissolved ALA or its salt. So the ALA's eventual state for both products should be the same as long as the final pH is the same. However, potassium might help curd some vehicles due to its contribution to ionic strength of the solution.

[orangehrzn]

So the pottasium salt would be as irritable as the acid because it is broken down to acid and pottasium in the solution?

[drtodorov]

At the same level of PH - yes. However, there may be a bit of a diffference because if the vehicle has low buffering capacity, the fact of adding a salt instead of the acid, changes the final pH (assuming you haven't equlibrated pH) and may affect the irritation potantial. But considering that ALA is a weak acid, the difference is not likely to be dramatic. Also, the irritation from AHA is probably not pH related (again since ALA is a weak acid), so the salt may be similarly irritating.

[cjdavis]

[drtodorov]

[Allyssa]

I just have a quick question about absorption. How long does it take for ALA to penetrate the epidermis?

[drtodorov]

I don't think this was studied, but it probably varies widely depending on a variety of factors. Most likely, the penetration starts within 5-10 min of application.