Trans-dermal patches contain the drug intended for trans-dermal delivery, along with all kinds of (often petroleum derived) adhesives, plasticizers, inhibitors, and permeability enhancers. I'm trying to find any information about whether any of these other substances, adhesives, enhancers, tackifiers, etc. have been found to also pass through the skin along with the intended drug in small amounts. I have been able to find a lot of information about the composition of various patch systems, as well as trials of how effectively the drug intended for delivery is absorbed, but absolutely nothing about whether any of these other petrochemicals present in the patch matrix also pass through. Is anyone aware of literature on this? Has it just not been studied?
My assumption would be that very minimal trace amounts of the petrochemicals comprising the patch matrix pass into the body along with the drug intended for delivery ~~ but that this has been determined to be a safe amount for relatively short term use. I'm specifically asking this question with transgender people who use hormones in mind. A transgender person who uses HRT as part of transition and chooses trans-dermal delivery, trace amounts of these petrochemicals over a long period of time could cause significant issues...
And as a secondary question, I'm wondering if there are any studies into whether the enhancers//inhibitors in the patch also enable other environmental contaminants to pass through the dermis undigested. To give an example, when I have used trans-dermal patches intended to be worn for 1 week, by the end of the week the patch will regularly get water and soap under the edges, and sometimes the middle as I shower. This from what I've read is normal, and it's suggested to just apply pressure after showering to re-adhere the patch to the skin. So, potentially chemicals that are in shampoos, soaps, and conditioners are coming in contact with the area of skin "prepared" for trans-dermal absorption of xeno-molecules everyday.
Below is a summary of what I've found about the materials used to produce trans-dermal patches:
From what I can gather looking at patents and studies, estradiol trans-dermal patches are generally comprised of 4 main categories of chemical:
(1) The drug intended for delivery ~ Estradiol
(2) An inhibitor such as propylene glycol to disable the role of the dermis in enzymatically digesting xeno-molecules before they enter the body... propylene glycol inhibits the enzymatic reaction that causes oxidation of estradiol into estrone.
(3) An enhancer such as Oleic Acid that is intended to enhance permeability of the skin and facilitate transdermal movement of xeno-molecules
(4) Adhesive polymer, this varies a lot from patch to patch but as an example this is what I was able to find for the Vivelle dot HRT patch ~~~ acrylic adhesive, polyisobutylene, ethylene vinyl acetate copolymer, 1,3 butylene glycol, styrene-butadiene ribber, mineral oil, dipropylene glycol… excerpt from NOVARTIS FDA document https://www.accessdata.fda.gov/drugsatfda_docs/label/2000/20323S23lbl.pdf
And here is a list of the ingredients specific to one brand of Estradiol patch called "Vivelle Dot":
The Vivelle system comprises three layers. Proceeding from the visible surface toward the surface attached to the skin, these layers are (1) a translucent flexible film consisting of an ethylene Page 2 vinyl alcohol copolymer film, a polyurethane film, urethane polymer and epoxy resin, (2) an adhesive formulation containing estradiol, acrylic adhesive, polyisobutylene, ethylene vinyl acetate copolymer, 1,3 butylene glycol, styrene-butadiene rubber, oleic acid, lecithin, propylene glycol, bentonite, mineral oil, and dipropylene glycol, and (3) a polyester release liner that is attached to the adhesive surface and must be removed before the system can be used.
Hi there! I found the info you provided is important since I am starting a new project "transdermal release". However, I am new in the field and would your guidance to understand the system and technique. All I have is an oily natural product and assigned to study the release from a polyester. Any help would be appreciated regarding the three layers components, sources, procedures ..etc
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