I overheard a woman talking about this very same subject in a bar the other night. She was saying how reusing old fentanyl
patches does and will work. She said from her experience that if one were using the matrix style patch (no gel) that she would gum a piece (very small piece the first time, placed in between the cheek and gum as far up as possible.) after the patch had been worn for 72 hours, and that in about 30 mins or so, she would feel the effects last for about 1 - 2 hours more or less. She also said that the brand of patch does make a big difference when using spent patches, the Mylan
generic brand patches for instance... total garbage. Towards the end of the night, she had told her friend that unless one was somewhat used to fentanyl, to be very very careful, and if that person starts to feel nauseous in anyway, to take out anything they have gummed and cool it for a bit, then start with a smaller amount. She then said something that I thought was very interesting, which is when you're gumming fentanyl, used or new, the less saliva you swallow the better. Something about how fentanyl's oral bio availability is crap, and how you will get more of the drug
absorbed through the mouth tissue than via yo tummy. She had also spout out some numbers and percentages of actual fentanyl left over in patches worn for 72 hours, she wasn't exactly sure, but had read online (from forums, not sure how accurate that can be) that there was something like, 35% of the drug left over, who knows. She was pretty cute too...probably shoulda got her number. Damn.