October 6, 2009 - 6:08pm
I've been thinking a lot about ER meds in light of all the threads discussing oxycontin, opana ER, and fentanyl recently. I'm on 2x20mg oxycontin per day. I understand that oxycontin has a biphasic release mechanism. My doctor basically gives me the freedom to determine my dosing schedule, and I will usually take one or two of my 7.5/325 percocets along with an oxycontin and a 350mg soma for my first dose of the day. I take the IR and ER oxycodone at the same time because it seems as if it takes a bit longer for the oxycontin to start working when taken alone, and I'm usually quite sore and stiff when I wake up in the morning. Also, taking a single oxycontin as my first dose typically has very subtle affects. Anyway, because of the biphasic release mechanism, I should experience another "peak" from the oxycontin at some point c. six hours later as if I had just taken a dose of 10mg of oxycodone, correct? Perhaps it is because of my tolerance and typically greater pain later in the day when I actually start moving around, but I don't feel that second "peak." I realize that doesn't mean the drug is released and circulating in my bloodstream, though, which I would think would increase the effectiveness of my redose of percocet around that same time since some amount of the drug is supposedly already actively in my system. So effectively, eight months into pain management and despite being on an "ER" medication, I'm still feeling the harsh ups and downs of what feels like just IR meds. 2.5-3 hours after dosing with oxycodone, as percocet or oxycontin, the affects are basically worn off, and the pain is back. This is becoming more of a problem now that I've been on the same daily dose of 70mg of oxycodone for over five months and I have apparently developed a significant tolerance to that dose. I don't think it is unreasonable to consider such a possibility after five months and to subsequently consider titrating up my dosage.
So, I know that there are many other medications such as morphine, oxymorphone, fentanyl, etc., with ER formulations, and there is of course the long-acting methadone option as well. My question then, is how do these medications work? I really don't think fentanyl should be an option for me at this point since I'm only these eight months into a lifetime of pain management and I don't want to go right to the top of the pain-medication latter and thereby limit my future options, but I wouldn't mind any input as to how it works (It basically just slowly seeps into the skin via Duragesic patch, yes?). Do formulations like MS-Contin, Avinza and Opana provide a steady release of medication that would subsequently maintain effects (i.e., analagesia) over an extended period of time? Is that the effect methadone has as well?
Any input into how extended release mechanisms work is very much appreciated :-) All the best,
Phil
October 7, 2009 - 11:23pm
#2
there is a release chart in archives here
showing the release rates of the various strengths of oxycontin, most start releasing after 25 minutes of comsumption an theres peaks of release about every 2 hours
You will have to find chart to be more specific
Woodstock
October 8, 2009 - 3:04am
#3
The peaks on those chart come
The peaks on those chart come about 45 minutes after administration time and roughly 6 hours after admin time...
October 9, 2009 - 5:32pm
#4
Ah, well then, I guess
Ah, well then, I guess switching to another biphasic ER medication wouldn't accomplish much of anything. Can either of you point me to this chart you mention? I've looked for it but haven't been able to find it. 
Thanks!
Phil
October 9, 2009 - 7:59pm
#5
Im not sure if you are aware
Im not sure if you are aware or not but Methadone isnt an ER medication. Methadone itself has a really long half life in some people more than 36 hours. However when you take methadone you will feel the peak pain killing effects 2-4 hours after administration, the peak lasts a lot longer than OC though usually until about 6-8 hours after administration. This is why when its giving for pain its usually dosed every 8-12 hours. Some people do take smaller doses more frequently but Im not a fan of that because of the way methadone builds up. On the other hand people can also take there whole days dose once daily. This option is usually reserved for maintenance therapy, since it basically puts you at a steady level and it stays that way all day and if the dose it high enough more than a day.
MsContin is not biphasic like OxyContin. MsContin releases it full dose after about 1.5 hours and the way the med is made it slowly tapers off over the next 8-12 hours making it a true extended release.
Avinza (morphine) has both immediate release beads and extended release beads in the capsules. The way that Avinza is made allows for q24h dosing. This med can take upto 4 days to reach its full pain killing effects.
Kadian, polymer coats beads of morphine (all ER no IR) can be dosed q12h or q24h.
OxyContin is a honeycomb like polymer structure imbedded with oxycodone that allows water/stomach/intestine juices to come in get a little oxycodone and seep back out into your system. Some people think the acrylic paint coating is what makes it ER but its not. Until youve seen a ghost tablet you may have trouble believing me on this if you have it set in your mind its the coating that makes it ER (not directed at anyone in particular, just anyone who reads it and disagrees). Not sure what chart the other posters are talking about, but in OC's prescribing info it basically says that you get half the pills dose after 0.6 hours (36 mins) and the other half at 6.9 hours (6hrs 54mins). The 36mins part was very accurate with me, but with name brand I got the second wave around 4 hours.
OPANA ER, an extended release pain medication, has a true matrix for every-12-hour dosing, per www.opana.com
You seem to understand how the patches work. Patch sticks there, that area of skin only allows so much drug soak through over a period of time. It kinda reminds me of those automatic water/food things for cats. As the cat eats the food more drops down. As the fentanyl soaks in more is released from the patch.
October 9, 2009 - 11:15pm
#6
its
on a thread over 3 pages long an prob. was started around january of 08, the chart was either on last page or , last of 2nd page.
like to see all charts an reference materials on a forum of their own, be highly conveinent.
Woodstock
October 11, 2009 - 4:25pm
#7
Fentanyl
is highly lipophilic, meaning that it is "attracted" to the fat in a persons body, just like THC in marijuana. When you put a fentanly patch on is will move from an area of high concentration (in the patch), to an area of low concentration (the fat under your skin) and will form a depot of medication there. That's why it's important to rotate application sites, because if you put one on where you had the last one, no (or not much) of the drug will move from the patch to your fat. Also people that don't have alot of body fat have problems with the fentanyl patch and subsequent overmedication, because they just keep upping the dose, when that's not the problem. Here is some information from the Duragesic PI. Hope this helps..
The DURAGESIC (fentanyl transdermal system) is a drug-in-adhesive matrix designed formulation. Fentanyl is released from the matrix at a nearly constant amount per unit time. The concentration gradient existing between the matrix and the lower concentration in the skin drives drug release. Fentanyl moves in the direction of the lower concentration at a rate determined by the matrix and the diffusion of fentanyl through the skin layers. While the actual rate of fentanyl delivery to the skin varies over the 72-hour application period, each system is labeled with a nominal flux which represents the average amount of drug delivered to the systemic circulation per hour across average skin. While there is variation in dose delivered among patients, the nominal flux of the systems (12.5, 25, 50, 75, and 100 mcg of fentanyl per hour) is sufficiently accurate as to allow individual titration of dosage for a given patient.
Following DURAGESIC application, the skin under the system absorbs fentanyl, and a depot of fentanyl concentrates in the upper skin layers. Fentanyl then becomes available to the systemic circulation. Serum fentanyl concentrations increase gradually following initial DURAGESIC application, generally leveling off between 12 and 24 hours and remaining relatively constant, with some fluctuation, for the remainder of the 72-hour application period. Peak serum concentrations of fentanyl generally occurred between 20 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 two system applications. By the end of the second 72-hour application, a steady-state serum concentration is reached and is maintained during subsequent applications of a patch of the same size. Patients reach and maintain a steady-state serum concentration that is determined by individual variation in skin permeability and body clearance of fentanyl.
After system removal, serum fentanyl concentrations decline gradually, falling about 50% inapproximately 20-27 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.
Ray
October 11, 2009 - 7:21pm
#8
There is atleast on generic
There is atleast on generic form of Duragesic that differs in its release than brand name. Mylan or maybe Watons has a liquid filled resevoir instead of a solid jelly/rubbery like brand. Or its the other way around.
October 11, 2009 - 7:40pm
#9
Mylan has no resivoir, all
Mylan has no resivoir, all other generics as well as brand have a "pocket" resivoir. The Mylan generics look very similar to the nicotine patch that is sold to help quit smoking. That is usually what people think it is if they happen to see mine due to rotation location. They say "oh, have you quit yet?" and I say "no, not yet". lol!! Any ways, I'm not sure about the liquid vs. jelly thing. I have a few old Watson ones around I save just incase I have one fall off or something maybe I'll open it and check but my pharm always orders Mylan for me since I discovered them.
October 12, 2009 - 12:42am
#10
The makers of Duragesic,
The makers of Duragesic, Ortho McNeil? I believe, have redesigned Duragesic. The brand name are just like the Mylan brand now. They did it for ease of use and safety, ie patches tearing. Many still think that they still use the resivoir design, but Ive been putting it out there for a while that they changed to the adhesive delivery system.
October 12, 2009 - 11:34am
#11
That's good to know
I refused to use anything other than the Mylan brand for that very reason. Duragesic is made by Ortho-Mcneil-Janssen. The release mechanism is the same for both the gel filled and the liquid filled. It's actually (the release mech) is all in the patch, it really doesn't have anything to do with what's in it. The Mylan brand use what is called a Silicone Matrix adhesive. The fentanyl is built into a matrix of silicone, which also acts as the adhesive. The other thing that differentiates the Mylan brand from others is that the size of the patch is directly proportional to the amount of fentanyl released. The others are not...Hope this helps
Ray
Hmmm. It is my understanding that most of the pill versions of ER meds are biphasic release...I think the only ones that are really continuous release are the patches...cant say for sure though...