How is Metformin Dosage Determined?

[ElloBee]

Great video, but shame it has not been updated with the results of the ACCORD study. Clearly, it is hard to justify anyone being put on more than 1000mg of Metformin without a very good reason. I expect that if GPs limited metformin to the 1000mg, a lot more people would take it due to fewer side effects, and above 1000mg there seem to be few additional benefits for most people. (Other the people find this website due to them not liking the side effects.....)

I am now flowering one more person on twitter.....

Ignore my previous reply Ringi, I've just spotted your other post explaining the ACCORD study (still figuring out how to use this site haha!). Thanks so much for the info, it's really appreciated!

 

[ElloBee]

I have often wondered about medication and weight ,children can't take some medication unless they are over 12 years old ,cats have to be weighed to determine the dose .I am well over 12x6 but I probably weigh less than some 12 year olds
Oh woe is me !!
CAROL

This is one of my concerns Carol, that if it isn't already, surely weight should be taken into account. Surely a smaller body cannot tolerate as much of the drug? Likewise surely a larger body could tolerate more. I am by no means a scientist or doctor though, so I am open to being told otherwise!

 

[Deleted member 308541]

Hi Tipetoo, I am pleased that the Metformin has been effective for you! Did your GP determine the dosage based on glucose levels or were there additional factors involved? (If you don't mind me asking!!)

He based it on my hba1c result that came back a lot a higher than previous ones.

 

[Sarah69]

I've taken metformin for a very long time. It's never worked for me as an appetite suppressant. A few years ago I was put on 6 x 500mg a day, although I started to take the dose at first then I kept forgetting to take them so I've never really taken that amount. I read a lot of people saying that 2000mg is the max dose but that can't be right if I've been prescribed more than that. It was a diabetic consultant at the hospital diabetic clinic that I attend who prescribed this amount.

 

[bulkbiker]

I'm really sorry to hear this. I genuinely hope things get better for you and that you can have better experiences.

Don't be sorry it has led to me taking control of my health and educating myself.
I feel empowered.

 

[Alexandra100]

This is one of my concerns Carol, that if it isn't already, surely weight should be taken into account. Surely a smaller body cannot tolerate as much of the drug? Likewise surely a larger body could tolerate more. I am by no means a scientist or doctor though, so I am open to being told otherwise!

I think weight and size matters more for some medicines than for others. Age can also count. Having good kidney function is a factor, and that tends to deteriorate with age. I'm not sure if there are other reasons older people are sometimes prescribed smaller doses. The leaflet that comes with the drug will usually mention the dose or doses recommended. When I was put on to the anti-coagulant Dabigatran I noticed that I qualified for the reduced dose due to age + low body weight but the specialist nurse disagreed and insisted I take the full dose. The lower dose of Dabigatran is known to be less effective in stopping blood clots than the full dose. I have not so far had any problems with it. BTW I am not a dr or scientist either!

 

[Alexandra100]

I read a lot of people saying that 2000mg is the max dose but that can't be right if I've been prescribed more than that.

There is some useful info. on Metformin dosage in this article by my much quoted Jenny Ruhl:

"One important point that my doctor missed when prescribing the ER version of metformin is this: The maximum dose of Metformin ER is LOWER than the maximum dose of regular Metformin.

According to the prescribing information, the maximum dose of the ER is 2000 mg a day. That of the regular is 2550 mg/day. Don't count on a pharmacist to catch the error if your doctor prescribes too much. Mine didn't, but I felt distinctly unwell on the high dose, and a quick look at the prescribing information online showed me the error.

Fortunately, a metformin overdose appears to be surprisingly benign. People have survived suicide attempts where they swallowed as much as 85 grams of the stuff at once. (They did develop lactic acidosis, which can be fatal, but survived.)

The dose at which metformin is supposed to be effective for most people is 1500 mg per day, though I know some smaller people who find a dose of 1000 mg effective. Your body weight will make a difference here, so if you are very large, you may need the maximum dose. In any event, don't conclude that metformin doesn't work until you have tested the dose up to the maximum.

It also takes up to two weeks for the full effect of metformin to become evident. While I will see an increase in my blood sugars if I forget a single day's dose, if I stop the drug for two weeks I see a slow rise in blood sugars through this period. My guess is that this two stage effect is because metformin works both on the liver (where it reduces the release of glucose) and the muscle (where it tricks the tissue into thinking it has just exercised and thus ramps up its burning of glucose). Whatever the explanation, give the drug a few weeks to see what it really does.

Also, many people who experience gas after taking metformin find that cutting way back on their intake of starchy carbohydrates helps eliminate the problem. "

You can read the full text here: http://diabetesupdate.blogspot.co.uk/2006/11/metformin-vs-metformin-er.html