Metformin vs. Metformin XR

I'm sorry to annoy you guys with yet another Metformin question, but here it is.

When my endocrinologist gave me the sample for Metformin, he gave me the XR version. I think it was because I was worried about the gastro side effects, but he didn't say. I take it once a day, at night after dinner, and though my BG isn't stellar, I no longer feel sick because of my BG. Overall, it works out pretty well.

Anyway, my endocrinologist's office wrote me a prescription for Metformin--not XR--by mistake. Does the non-XR version last all day, or only a few hours? Should I have them rewrite the script for the XR version?

Also, I kinda already filled the Metformin prescription (I didn't notice that it didn't say XR, I was just so happy to have the prescription!). Do you think my pharmacy will fill the script for XR even though I have the non-XR in my possession? Does anyone think my insurance will cover the extra script?

Thank you!

A couple of ways to go here. Many people don't experience gastro side effects from regular Metformin (I don't). So you could try it and see what happens.

Or, operating on the principle of "if it ain't broke, don't fix it", you could have them rewrite the scrip for XR, since you know that seems to be working.

My impression is that the XR version works more slowly and for a longer time, but I don't know that for a fact.

As for how your insurance will respond . . . . that varies drastically from company to company -- impossible to predict. Only one way to find out for certain -- try it.

As long as you don't have gastric distress, you should be fine. You may need to take it 2-3 times/day, but it should be fine. The max dose of metformin is actually higher than metformin XR.

Well, the whole problem is that I'm only taking it once a day. I'm worried that it'll wear off a few hours after I take it (or even before breakfast) and then I'll be stuck for the rest of the day with no Met in my system.

Guitar, I can't find the duration of action of the XR version but one can assume that it lasts longer than 8 hours since it can be used once a day whereas the regular Met is usually 2 or 3x a day. It is recommended that the XR (or ER for extended release) be taken with the evening meal. I was first asked to take the ER Met 2x a day but had way too low BGs and finally talked my endo into the once a day/evening meal dose. I have type 1 and it helped me to reduce my total insulin dose. I was getting insulin resistant.

Actually, metformin has three actions and much of the action will accumulate over weeks, even with regular as opposed to XR. Blood levels of metformin have a major peak over a period of hours, but it actually is absorbed in your cells over a much longer time frame.

Why can't you just split your doses?

Into 250 and 250? Hmmm, that's actually not a bad idea.

Has anyone had experience splitting the metformin pill?

This is a very resourceful and innovative group. Wondering if splitting the pill has helped people 1. adjust to the effects of taking metformin 2. achieve better BG control.

You can split metformin but metformin XR should specifically not be split. If you split the metformin XR it breaks the matrix which makes it long acting.

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@Brian_BSC. That makes sense to not split the XR. Do people split the immediate release regular Metformin because the 500 mg is too potent? are they trying to slowly adjust to the GI upsets by taking smaller quantities?

People may split dosages for different reasons. You might split them because they are too large, potent or you want a half dose. If you need a dosage of 2500 mg/day then getting a Walmart prescription for metformin 1000 mg for $4/month and save money. If you are sensitive to the gastric side effects one way to adjust is certainly moving slowly up in dosage by splitting.

Does Metformin hurt the kidneys? I was taken off of it because of that.

While we’re talking about metformin - is it to be taken with a meal because that helps with gastric upset, or because it aids in absorption? My doctor initially told me to take it in the evening (not necessarily with dinner - she suggested before bed, actually)

Metformin itself doesn’t hurt the kidneys, the problem is that metformin is excreted by the kidneys. And if your kidneys are working properly the metformin can accumulate in your system to potentially harmful levels. The prescribing information advises doctors to monitor renal (kidney) function and if your serum creatinine levels get too high you should not take metformin.

For many people taking metformin with a meal can reduce gastric distress. Some doctors advise taking part or all of your dose at night, presumably to help protect again morning highs (Darn Phenomenon).

My doctor wanted me to take all 4 Diabex XR tablets after my evening meal because that way the medication works consistently over the 24 hour period. And that was when my problems with the XR type of medication started. I got no side effects from taking them all at once, but I found it extremely difficult to cope with the sight of the 4 ‘horse tablets’ and my throat would close up in protest. I am now on Diaformin which you take 3 times a day and which can be broken in half or crushed. As Brian stated above, XR tablets cannot be broken up.

Thank you all!