Fentanyl in the form of Duragesic patches comes in dosages of 1.25, 2.5, 5, 7.5, and 10mg. It is a continuous release product, and release depends on surface area. The sizes of the patches for each dose are 5, 10, 20, 30, and 40 cm, respectively. 2.5mcg/cm2 are released per hour. Users who abuse fentanyl, or take recreationally should take extreme caution. 100ug of fentanyl taken transdermally
over an hour is equivalent to between 5-10 mg of IV morphine taken over an hour. It is unlikely that many people will ever encounter this patch size, but should be wary even of the smallest ones. Fentanyl has a bioavailability (the amount of a drug
which remains unchanged and crosses the blood brain barrier, i.e has any effect on the user) of nearly 100% transdermally. This means that whereas taking an opiate orally enables perhaps a third of the drug to enter the brain- so 100mug of oral fentanyl is really around 35mug- when applied to the skin, nearly all of the fentanyl reaches the brain.
In the form of Actiq, because buccal bioavailability is only about half that of transdermal, dosages are 200, 400, 600, 800, 1200, and 1600 mcg. With Actiq, some of the fentanyl is absorbed transbucocally, while more of it is swallowed (ie passes through the liver), therefore first pass metabolism has a significant effect. That is why the dosages differ so greatly.
Duragesic patches were originally made with a gel in which the fentanyl was suspended, but quite recently the delivery system was changed, as leaky patches were associated with multiple deaths. However, it may still be possible to obtain gel patches, so information about their use is necessary. In addition, it is also be possible to chew the sans gel patches to attain a similar effect.
It is inadvisable for even the most opiate tolerant user to attempt injection of fentanyl. A much "safer" way to abuse the patch is to cut one end of the square off and suck on it in order to ingest the gel, although as mentioned earlier, ingestion would substantially decrease bioavailability, but would counter the time-release. Both of these are dangerous, as it is difficult to discern exactly how much fentanyl is really being put inside the body. For patches without gel, i.e Mylan
brand patches, it is possible to cut off pieces and chew them. It is also possible to smoke the gel (after drying it), but this is inadvisable as opiates
break down in the presence of extreme heat so it is a fairly inefficient route of administration.
As a precaution, keep in mind there is anecdotal literature about possible hepatoxicity associated with chronic ingestion of the gel.
In order to prepare for sublingual use the patches must be cut up evenly in order to obtain squares with equal amounts of fentanyl. Whilst the patches are designed for continual use over 72hours they contain much more fentanyl than is required:
12mcg/h - 5.25cm² - 2.1mg (2100ug) total content
25mcg/h - 10.5cm² - 4.2mg (4200ug) total content
50mcg/h - 21cm² - 8.4mg (8400ug) total content
75mcg/h - 31.5cm² - 12.6mg (12600ug) total content
100mcg/h - 42cm² - 16.8mg (16800ug) total content
Same total content for all equivalent strenghts. However they have a 12.5mcg/hr patch instead of a 12mcg/hr patch but both contain 2.1mg. They also have a 37.5mcg/hr patch which has 6.3mg in total.
Fentanyl Actavis and Ratiopharm:
12mcg/h patch has the total of 2.063mg of fentanyl (Ratiopharm only)
25mcg/h patch has the total of 4.125mg of fentanyl.
50mcg/h patch has the total of 8.25mg of fentanyl.
75mcg/h patch has the total of 12.375mg of fentanyl.
100mcg/h patch has the total of 16.5mg of fentanyl.
12mcg/h patch has the total of 1.38mg of fentanyl.
25mcg/h patch has the total of 2.75mg of fentanyl.
50mcg/h patch has the total of 5.5mg of fentanyl.
75mcg/h patch has the total of 8.25mg of fentanyl.
100mcg/h patch has the total of 11mg of fentanyl.
Example of how a patch may be divided up (Durogesic and Sandoz):
50mcg/hr patch containing 8400ug would be cut into 1/2, then 1/4s, then 1/8s then 1/16ths but cutting exactly in half each time. This would give 16 squares each with 525ug. These could then be cut into 5 to give 105ug squares. If chewed for sublingual absorption
(bioavailability 50%) this would equate to 2.5-5mg of IV morphine. If swallowed (oral bioavailability 33%) it would be equal to 1.7-3.3mg of IV morphine. This method can be applied to 12mcg/hr, 25mcg/hr and 100mcg/hr by increasing or decreasing the amount of times cut in 1/2 proportionately to the reduction in strength i.e. 25mcg/hr would need cutting in 1/2 one time less than 50mcg/hr as it is half the strength. This method is applicable to 37.5mcg/hr and 75mcg/hr but the final squares are cut into 4 not 5. 37.5mcg/hr requiring 4 divisions by 2 and the 75mcg/hr needing 5 before each square is cut into 4 pieces.
For Activas and Radiopharm the same can be used producing squares with a very small amount less of Fentanyl. The same is not applicable to the Matrifen patches however. These each require differing amounts of division by different numbers:
To obtain 100ug pieces:
12mcg/hr cut in 3 then 4 (gives 115ug)
25mcg/hr cut in 3 then 3 then 3.
50mcg/hr cut in 3 then 3 then 3 then 2.
75mcg/hr cut in 3 then 3 then 3 then 3.
100mcg/hr cut in 3 then 3 then 3 then 4.
As well as being taken orally or sublingually the patches can be vaporized however this is far more likely to lead to an overdose as absorption is nearly 100%. 100ug smoked could be as strong as 10mg of IV morphine. Effects become apparent in seconds and can easily overpower even opiate tolerant users. Vaporizing is achieved by heating a piece of patch on tin foil and inhaling the vapour. This is the most dangerous method of consumption other than taking it IV.
Remember: the patches are designed for continuous release. Therefore when one cuts open the patch, a total of 5, 7.5, 10 etc mg are available. The patches are designed to release 100mcg fentanyl/10cm2/hr. 100mcg is equal to around 10 mg of morphine, and 10 mg of Fentanyl is equal to almost a gram of morphine. This would lead to fatalities in all but the highest of opiate tolerance users. Fentanyl has an LD50 (the dose at which 50% die) of .03 mg/kg. In humans it is undetermined, but this would mean perhaps 2.1mg of fentanyl (for a 70kg user) gives users a 1/2 chance of dying. If users don't have a legitimate prescription for Fentanyl, or are not heavily addicted to opiates, abuse of Fentanyl is highly- dangerous and should be avoided at all costs.