Gabapentin and oxycodone (possible DE-potentiation)???

[infraredz]

I read here, and a few other places the following general statement:

Chromophobia:
"Gabapentin before an opioid will decrease the opioids absorption but gabapentin after the opioid will potentate it. So in your case it's always best to take the opioid first."

~NaStYNaI~:
"gabapentin before oxy will lower the bioavailability of the oxy...but taking the gabpentin AFTER your oxy dose will raise the bioavailability of the gabapentin....supposedly"

The quote I found in several threads:

"But people who take Neurontin (gabapentin) for pain, as fibromyalgia is far too common in the bipolar community, Neurontin (gabapentin) has a weird drug-drug interaction with opiates. The opiates make Neurontin (gabapentin) work better, but the Neurontin (gabapentin) makes the opiates less efficient! It's weird, and since Neurontin (gabapentin) isn't really metabolized, who the hell knows what the deal is with that. This is spelled out in the PI sheet, but who reads those, right? When you take Neurontin (gabapentin) along with hydrocodone (a.k.a. Vicodin), it decreases the bioavailability of the hydrocodone by up to 22%! While the bioavailability of Neurontin (gabapentin) is increased by 14%. It's even odder when combined with morphine. As Mouse points out there's an element of timing involved, as XXXXX (deleted gov link) on the interaction has morphine administered two hours before the Neurontin (gabapentin). The morphine was unaffected, having pretty much been on its way towards peak plasma, but the Neurontin (gabapentin) bioavailability was increased by a whopping 44%! We have no idea if this effect carries over to the artificial opiods, like Demerol or buprenorphine.
Meanwhile taking naproxen (a.k.a. Aleve) increases Neurontin's bioavailability by 12-15%, while there is no apparent affect on naproxen's bioavailability

From the prescribing information (for professionals by Pfizer)

Coadministration of Neurontin (125 to 500 mg; N=48) decreases hydrocodone
(10 mg; N=50) Cmax and AUC values in a dose-dependent manner relative to administration of
hydrocodone alone; Cmax and AUC values are 3% to 4% lower, respectively, after administration
of 125 mg Neurontin and 21% to 22% lower, respectively, after administration of 500 mg
Neurontin. The mechanism for this interaction is unknown. Hydrocodone increases gabapentin
AUC values by 14%. The magnitude of interaction at other doses is not known.

Gabapentin is not metabolized (above 90% is excreted unchanged in urine) so there is no CYP enzyme involvement with the two. Also, Gabapentin is best absorbed without antacids (so I'm guessing that means a basic environment is best for oxycodone, but worse for gabapenting [but it could be due to calcium and magnesium carbonate specifically]). Can anyone shed some light on this?


Mods, I feel like this may be an ADD thread so move at your discretion....

 

[bronson]

Moving this BDD --> ADD

 

[sekio]

The mechanism for this interaction is unknown.

It says so right there... Gabapentin decreases the total amount of hydrocodone absorbed into the blood. We don't know exactly why.

 

[infraredz]

It says so right there... Gabapentin decreases the total amount of hydrocodone absorbed into the blood. We don't know exactly why.

Right, but what about oxycodone? They are both codeine based rather than morphine based and I'd imagine the metabolism is similar between the two so I was wondering what Gabapentin's role in oxycodone metabolism is...

 

[Hammilton]

codeine or morphine based, it's all irrelevant. That's a question of a CH3 group. A super minor difference.

 

[Raginrondo]

A friend and I frequently used oxymorphone and at the time she was prescribed to Lyrica and when she would combine the drugs she would basically become incoherent from being so faded out. Is it safe to assume that since oxycodone is metabolized into oxymorphone, that oxycodone would have similiar effects with gabapentin?

 

[Kratom bomb]

I have read the entire FDA study on gabapentin and it doesn't effect all opiates the same way. Morphine administered 2 hour prior to gabapentin increases gabapentin in the blood by 44%, that's huge. Gapapentin coadministered with hydrocodone decreases hydrocodone in the absorption 14%. There was nothing in the published study about oxycodone, so it was most likely not studied. If not, you may only have personal experience from others as information. It's the official study, so it is Extremely long but here is the link. I will break the link by putting hxxp:, instead of http:, you just need to replace the x's with t's.

 

[bloodshed344]

I have read the entire FDA study on gabapentin and it doesn't effect all opiates the same way. Morphine administered 2 hour prior to gabapentin increases gabapentin in the blood by 44%, that's huge. Gapapentin coadministered with hydrocodone decreases hydrocodone in the absorption 14%. There was nothing in the published study about oxycodone, so it was most likely not studied. If not, you may only have personal experience from others as information. It's the official study, so it is Extremely long but here is the link. I will break the link by putting hxxp:, instead of http:, you just need to replace the x's with t's.

You didn't write the link!

 

[DJHENRU]

Too much gabapentin causes the shits, maybe it's because it's a Zwitterion needing to be ingested. Opiates slow down gastric secretions and their primary effect is in the liver(read that if you have a liver removal or something opiates won't work even if they are not related to being converted.)
Sorry if none of this data is clear but I'm just guessing. Probably pro drugs are effected by changes in the gut, never causing secretion changes(far fetched) before converting. Non prodrugs change secretion so gabapentin gets the ba increase(also I found too high ba can be a downfall for lyrica for chronic pain)