Here is a link with a long argument consisting of the manufacturer of Catapres TTS patches disputing Mylan's attempt to make a generic form.
It is long but if you read it you will see they refer to a "rate limiting" membrane on their product.
Further down however, there is a study showing increased rates of absorption during hot/humid conditions.
Quote:
Hull cites other studies finding that application of heat resulting in subcutaneous
temperature increases caused a threefold, four to sixfold, and even a ten to twelvefold
increase in skin blood flow, respectively. Id. Enhanced cutaneous blood flow during heat
exposure dramatically alters the pharmacokinetics of many transdennally administered
drugs. The results of these studies indicate that external heating is significant for
transdermal as well as subcutaneous drug absorption, resulting in increased plasma drug
concentrations.
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The claim is that the parent company has this rate limiting membrane that is supposed to minimize alterations in drug delivery. Given that Clonidine is a
narrow window of safety drug, it boils down to who do you believe.
The majority of patches I see are used in nursing homes and hospitals, and
in the general public by children. These patches are not common in the general public, so I don't expect medical personel to know details of them without looking those details up.
Quote:
It is thus apparent that clonidine at inappropriate levels can be dangerous to
patients.
Ii
is also apparent that, for other potent transdermal drugs, like fentanyl,
experience with heat, etc., has produced toxicity associated with overdose. Catapres-TTS,
on the other hand, has had a remarkable safety record, when the patch has been used in
accordance with its labeling, during the 20-year historical patient experience with the
product.5 We believe, therefore, that the rate-controlling membrane of Catapres-TTS
serves the purpose of controlling the delivery of clonidine and thus avoids what could be
significant safety risks with a patch that lacks the patient-protection features of Catapres-
TTS. Generic versions lacking such a membrane differ significantly in their inactive
ingredients, a difference that raises safety issues. As the ANDA applicants, the burden is,
of course, on Mylan and Elan to demonstrate that their different release mechanisms do
not in fact pose these risks. If they cannot, approval under an ANDA is prohibited.
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Given that accidents with patches continually come up as "new"information, I would not speculate on the total believeablilty of the Catapres system. But I tend to be cautious. This argument in this paper is targeting allowing Mylan to market a generic version. As you read, you see the difficulties presented by both sides of that argument.
So I would caution you not to expose the skin or body areas to heat, just in case.
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All truths are easy to understand once they are discovered; the point is to discover them.-- Galileo Galilei
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Weezie looking at petunias 8.25.2017
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