How much reduction in absorption of gabapentin is there if one takes more than 600 mg?

[SueJohnson]

I have been taking 1400 mg gabapentin divided into 700 mg at 7:15 and 700 mg at 9:15, going to bed at 10:15. I increased this to 1500 mg on July 5th, with 700 mg at 7:15 and 800 mg at 9:15, but last night had restless legs. I know I should switch to pregabalin but it is expensive. I know that in taking more than 600 mg there is less absorption so I thought I might take 300 mg at 5:15 and then 600 mg at 7:15 and 9:15. To compare how this would work, I really need to know how much less the absorption is after 600 mg. Is it 90%, or 80%? Does anyone know or have an idea?

[Hidden]

Hi Sue. There dosen't seem to be any consistent information on this, different sources give different figures.

I have seen a graph, but unfortunately this forum doesn't allow attachments so I can't post it.

According to this graph the amouhjt absorbed for each dose appears to be about -

Of 100mg taken you absorb approx 80mg

Of 400mg taken you absorb approx 200mg

Of 600mg taken you absorb approx 250mg

Of 800mg taken you absorb approx 330mg

Of 1000mg taken you absorb approx 380mg

Of 1200mg taken you absorb approx 400mg

Of 1400mg taken you absorb approx 420mg

These figures suggest that doubling the dose from 600 to 1200mg gives about an extra 150mg.

An increase of 200mg from 1200mg to 1400mg gives about an extra 20mg.

These figures are based on it being administered three times daily once every 8 hours. I guess for two split doses, these amounts may further decrease.

In addition the time between taking it and the maximum availability in the blood stream also varies.

At 100mg it takes 1.7 hours, but takes up to 3 to 4 hours at higher doses.

[SueJohnson in reply to Hidden]

Thanks. What do you think of my proposed schedule?

[Hidden in reply to SueJohnson]

I can only quote from an article written by a Prof of Neurology updated in May 2021

"The usual effective dose is 900 to 2400 mg daily given in a single dose or divided one-third at midday and two-thirds in the evening for maintenance doses ≥600 mg daily.

Especially in doses above 1200 mg, the administered dose may not correlate well with serum levels because of nonlinear kinetics."

see this link

uptodate.com/contents/treat...

Based on the graph and on this, my personal feeling is that spltting the dose more than twice is of little value

[SueJohnson in reply to Hidden]

Well, I will try it and post back whether it works.

[Hidden in reply to SueJohnson]

OK let us know.

[SueJohnson in reply to Hidden]

I tried it last night and it worked. 🙂

[Hidden in reply to SueJohnson]

Great, but be aware one night doesn't prove anything.

Fingers crossed!

[SueJohnson in reply to Hidden]

I agree. Will update again in a few days.

[SueJohnson in reply to SueJohnson]

4 days now. I think at this point I can say it works !!!

🙂

[SueJohnson in reply to SueJohnson]

However, since I play ice hockey on Monday nights and this means I would have to take 300 mg while driving, I have decided to switch to pregabalin even though it will cost more.

[Madlegs1]

By any chance, are you taking any form of magnesium? Either straight or as an antacid etc.?

[SueJohnson in reply to Madlegs1]

No

[Madlegs1 in reply to SueJohnson]

🥴

[Carlettejaque]

I've been taking 800mg 3 times a day. One dose early morning, One at 2pm and one at 9pm. I got an increase of benefit by increasing from the 700mg doses . If I try to decrease I do find a big difference in neuropathic pain relief decrease. I wouldn't want to decrease. So, to answer your question, yes, increasung from 700 to 800 does make a difference. Can I ask please, have you found that gabapentin causes a huge weight gain, and swelling in the legs or feet? I've put on 3 stone and my left leg and foot has had swelling since I began taking it 2 years ago.

[SueJohnson in reply to Carlettejaque]

Yes I have developed edema. And I have had a slight weight increase - 3 pounds.

[Nerakeel24 in reply to Carlettejaque]

Can I ask if you experience restless legs during the day as well as at night and for this reason you begin taking the Gabapentin in the morning?

[Carlettejaque in reply to Nerakeel24]

I started taking Gabapentin 28 months ago as a treatment for neuropathic skin pain. An agonising condition that affects every single inch of my skin. The gabapentin stops the pain completely. Despite the side effects i wouldnt want to stop taking it. I started getting the RLS and hot feet syndrome 10 months ago. The Gabapentin didn't prevent me from getting RLS. As the day progresses my feet get hotter and hotter until they burn and sting. During the day I use a pet cooling pad which I cool in the fridge . During the evening I put my feet in ice water. I sleep with my feet uncovered and I put a bottle of frozen water between my feet. If I don't get my feet cold or they warm up I get the RSL. I'm dreading this weekend's heatwave . It's an awful feeling isn't it. I don't get the unintentional movement or jerks that some people get but because of the horrible feeling in my legs i have to keep moving them. It's not something you can ignore and sleep through. I dont usually get the RSL during the day, only during the evening and night. People just don't understand what an awful problem RLS is.

[Nerakeel24 in reply to Carlettejaque]

Oh dear that sounds miserable. I'm so sorry you have to go through such misery! I hope things get better for you! I only get restless legs at night and have been trying to figure out how much gabapentin to take, and at what times, to get the best relief. RLS is absolutely miserable! all the best...

[Carlettejaque in reply to Nerakeel24]

You could try increasing to 800mg a day taken 3 times one when you get up in the morning between 7 & 8am again at 2pm and the last dose at 9pm good luck. Hope it helps.

[Muso-man]

Hi Sue I take 300 at 5-6 o’clock and 600 at 11.00 o’clock. 12 moths and seems to be ok.