Something I never understood in pharmacology

[tofutti]

I was wondering if you nursing students can explain something to me?

I took pharmacology as a prereq, so I'm not in the program yet.

If someone has a, say, 25mcg (I forget the units) fentanyl patch, then how much is really in the patch? How much is released per day, or hour, or what? How long does the patch last?

Hope I'm asking clearly in my confusion. Thanks, Tofutti

[carolinapooh, BSN, RN]

A 25 mcg fentanyl patch has 25 mcg of fentanyl on it. The drug is released over time through the patient's skin and the absorption rate is generally constant at "normal" skin temperature. As with any patch, many things can affect absorption rate, such as body temp and chemistry. The amount of fentanyl in the blood increases gradually after application, reaching a peak after 12-24 hours. Once this concentration is achieved, blood concentrations remain constant over the 72 hours that the patch is worn. After removal of the patch, blood concentrations of fentanyl decrease slowly due to ongoing absorption of fentanyl remaining on the skin.

My father used fentanyl patches for chronic pain due to peripheral neuropathy. I was also a pharmacy tech and filled scripts for them all the time.

[tiggerslj9]

My understanding is that the 25 mcg/hr patch delivers 25 mcg per hour. It is worn for 72 hours ... so the patch actually contains (25 * 72) 1800 mcg of the medication and has a controlled release.

There was a story locally where a bunch of teenagers stole the 1 teens mother's Duragesic patches & licked them ... 1 of the teens died and the other ones were in ICU because they received such a high dose of the medication at the same time. The teen that died was the daughter .... her mother was dying of cancer and that is why she had the patches. It was a really sad situation.

[Daytonite, BSN, RN]

this is the pdr information on fentanyl (duragesic) patch. the specific, official information you are looking for is here.

http://www.drugs.com/pdr/fentanyl.html#g05