Sciencemadness Discussion Board

Topical Anasthetics in DMSO

Picric-A - 10-10-2009 at 06:21

I have given this some thought for a while but still havnt come to a conclusion so if anybody knows better please let me know.

Topical anasthetics are local anasthetics which and administered onto the skin in solution and i guess are absorbed by it. An common example of this is benzocaine or tetracaine.

Now when something like benzocaine(in a mix of water/ethanol) is applied to the skin the numbness can barely be felt. Would the numbness be greatened if dissolved in something like DMSO? this is readily absorbed by the skin and polar so should dissolve the benzocaine.

In hospitals they use this cream form of topical anasthetic known as 'magic cream' to numb the skin before an injection for infants. Does anybody know what the solvent in this is?

Thanks,

JohnWW - 10-10-2009 at 07:30

I happen to have a 500 ml bottle of DMSO that I bought OTC at a local pharmacy several years ago (I had to shop around to find one that both had the stuff and would sell me some), thinking that applying an aqueous solution of it with a cloth to the skin over an affected area might help cure arthritis, at least temporarily, in the light of media reports then about discovery of its anti-inflammatory effect on arthritis. The results were minimal, though.

I also have a phial of the FeCl3 complex of DMSO that I made in an university chemistry lab class over 40 years ago. It contains both a DMSO-complexed Fe(III) cation and the FeCl4- anion. As the result, it would be an interesting study in Mössbauer spectroscopy, due to its containing two differently bonded types of Fe atoms.

I understand that DMSO is able to deeply penetrate tissue through the skin. This is probably the basis of the dissolution in it, as a carrier, of local anaesthetics (cocaine, and its synthetic analogs such as benzocaine, lidocaine, xylocaine, tetracaine, etc.), for delivery to the sites concerned through the skin by topical application. The anti-inflammatory (or at least alleged) property of DSMO would have an added synergistic effect.

Picric-A - 10-10-2009 at 07:40

Hi John, how much did you pay for your 500ml DMSO? I have been offered 500ml Merk spectroscopy grade for £28. Is that a rip off?

entropy51 - 10-10-2009 at 09:12

Quote: Originally posted by Picric-A  
In hospitals they use this cream form of topical anasthetic known as 'magic cream' to numb the skin before an injection for infants. Does anybody know what the solvent in this is?
It isn't DMSO. Its known as EMLA, eutectic mixture of local anesthetics.

See here. You can find lots by searching for that name.

[Edited on 10-10-2009 by entropy51]

JohnWW - 10-10-2009 at 12:03

I think it cost around $NZ 15 to 20, which at the current exchange rate would be about £8 or 9. It is probably Pharmaceutical Codex grade, rather than Spectroscopic Grade which would be purer.

Formatik - 14-10-2009 at 16:14

Quote: Originally posted by Picric-A  
Now when something like benzocaine(in a mix of water/ethanol) is applied to the skin the numbness can barely be felt. Would the numbness be greatened if dissolved in something like DMSO? this is readily absorbed by the skin and polar so should dissolve the benzocaine.


Yes, it's got the ability to carry such compounds through the skin. I've done this with a local anaesthetic (meant for injection): I've put 0.4mL 1% of procaine on the right hand, and then 0.4mL 1% procaine mixed with 0.3mL 99% DMSO on the left hand in the same spot, rubbed them in slightly and then let evaporate. The DMSO/procaine caused some numbness, but just procaine didn't really do anything. Pinching the area with the same force also showed the difference between the two, with the right side being significantly more sensitive. Paper on using watery cocaine.HCl or 5% tetracaine (as topical anaesthetics) in DMSO: http://www.ncbi.nlm.nih.gov/pubmed/2354023

stateofhack - 14-10-2009 at 17:34

Quote: Originally posted by Picric-A  
Hi John, how much did you pay for your 500ml DMSO? I have been offered 500ml Merk spectroscopy grade for £28. Is that a rip off?


yes.

a_bab - 17-10-2009 at 03:32

Different fats/oils (even butter for instance) are known to penetrate the skin. That's how all of these body lotions/gels/whatever work.

Actually, a bit of alcohol mixed wih butter and rubbed on the skin will give quite a nice rash due to the alcohol being carried in the skin.

Swede - 20-10-2009 at 13:07

DMSO (I doubt the purity) can often be found as a liniment for horses at feed stores and veterinary supplies in the U.S... usually by the gallon. I don't know about Europe.