skrape, I think your doctor is probably just conveniently interchanging the words "can't" and "won't" as far as changing the patch every 48 hours versus 72 hours.
My doctor told me before I even started the patches that he was going to prescribe them for 72 hours to begin with, but that it wasn't at all uncommon for them not to last the full 72 hours. For the first month I was on the patches, I just took double my BT meds on the third day. When I went back for my 1-month follow-up visit, he changed me to every 48 hours.
It's also addressed in the prescribing information for each different manufacturer. The Duragesic brand prescirbing info can be found here: http://www.accessdata.fda.gov/drugsatfda_docs/label/2005/19813s039lbl.pdf
prescribing info said...
The majority of patients are adequately maintained with DURAGESIC® administered
every 72 hours. Some patients may not achieve adequate analgesia using this dosing
interval and may require systems to be applied every 48 hours rather than every 72 hours.
An increase in the DURAGESIC® dose should be evaluated before changing dosing
intervals in order to maintain patients on a 72-hour regimen. Dosing intervals less than
every 72 hours were not studied in children and adolescents and are not recommended.
I have to respectfully disagree with just about
everything you've posted, Morgoth.
When they're prescribed and used appropriately, Fenanyl patches are just as safe as any other narcotic pain medication on the market. Frankly, it's the level of misinformation surrounding Fentanyl patches that fuels the hysteria surrounding them.
For example, Fentanyl patches are absolutely contraindicated for short-term use. There have been numerous warnings issued to doctors for inappropriately prescribing fentanyl patches to patients that don't require long-term, 24/7 dosing of narcotics to manage their pain. For patients that require short-term management of their pain, the risks involved with the patches don't outweigh the benefits; those patients can and should be treated with oral medications.
In addition to that, based on the nominal rate at which a new patch infuses fentanyl into the skin and the half-life of the residual fentanyl remaining after the old patch is removed, it is mathematically impossible to get a "double" dose by removing an old patch and placing a new patch - whether you do it at 48 hours or 72 hours. The actual numbers for each brand are readily available and can also be found under the pharmicokinetics section of the prescribing information (linked above).
prescribing information said...
Peak serum concentrations of fentanyl generally occurred between 24
and 72 hours after initial application (see Table A). Serum fentanyl concentrations
achieved are proportional to the DURAGESIC® delivery rate. With continuous use,
serum fentanyl concentrations continue to rise for the first few system applications. After
several sequential 72-hour applications, patients reach and maintain a steady state serum
concentration that is determined by individual variation in skin permeability and body
clearance of fentanyl (see graph and Table B).
After system removal, serum fentanyl concentrations decline gradually, falling about
50% in approximately 17 (range 13-22) hours. Continued absorption of fentanyl from the
skin accounts for a slower disappearance of the drug from the serum than is seen after an
IV infusion, where the apparent half-life is approximately 7 (range 3-12) hours.