I just stumbled across something interesting. I am having difficulty getting my carbomer to dissolve in the transdermal mix. Taking some advise from another post, I tried heating the mix. I didnt work. The carbomer is still clumping. Pissed off, I dumped the mix back into my pump bottle and applied my morning dosage. It was very warm (I would guess about 150 deg F). It appeared that that my homebrew solution absorbed in about half the normal time! This based on typical drying time and the oiliness (from the PG) after applying the solution. After observing this, I did some research and found a number of studies (including one with testosterone) that supports the theory that heat dramatically increases the flux of topically applied drugs. Apparently heat increases the kinetic energy of the drug molecules and increases the solubility of the drug in formulation. Heat also dilates the skin pathways, increasing the movement of the drug though the skin.
So, the question becomes how to conveniently heat our homebrew solutions prior to application. I have seen warmers for shaving cream, coffee cups, etc. I was thinking about some type of electrical warming container that could be plugged in just prior to showering. You get out of the shower and apply your warmed homebrew.
What do you think?
Here are some studies.
A pilot study assessing the impact of heat on the transdermal delivery of testosterone.
Shomaker TS, Zhang J, Ashburn MA.
University of Hawaii, John A. Burns School of Medicine, 1960 East-West Road, Honolulu, HI 96822-2319, USA.
This study evaluated the effect of locally applied heat on the transdermal delivery of testosterone. Six healthy adult volunteers were tested three times while receiving a 5 mg androgen patch, the same patch with a heat-generating patch, and no patch at all over 12 hours. Statistically significant differences in mean maximum serum testosterone concentration values were seen. Heat plus patch resulted in a mean maximum serum testosterone concentration of 939 ng/dl versus 635 ng/dl (patch only) and 425 ng/dl (no patch). (Heat + patch vs. no patch: p < 0.001; heat + patch vs. patch: p < 0.001; patch vs. no patch: p = 0.003.) The area under the curve of plasma testosterone concentration versus time values were means of 4114 ng/dl.h versus 1985 ng/dl.h for the patch-only group (p = 0.001). The use of heat improved absorption of transdermal testosterone and decreased time to peak serum testosterone concentrations, resulting in a statistically significant difference in mean maximum serum testosterone concentrations compared with the use of the patch without heat.
Heat-Enhanced Transdermal Drug Delivery: A Survey Paper
Wade Hull, MS
.Heat is known to increase the kinetic energy of both the drug molecules and the proteins, lipids, and carbohydrates in the cell membrane. Heating prior to or during topical application of a drug will dilate penetration pathways in the skin, increase kinetic energy and the movement of particles in the treated area, and facilitate drug absorption .
.Heat is also expected to enhance transdermal drug penetration by enhancing solubility of the drug in formulation. As a general rule, the aqueous solubility of inorganic and organic solid drugs increases with increasing temperature .