[CARPA] Fwd: Re: swapping to Metformin XR

Thu Apr 19 11:27:53 EST 2007

The pharmacokinetics of metformin is tricky. Metformin is absorbed in
the upper GI tract and is water soluble making it hard to release the
drug slowly in a XR form and to keep it in the right place long enough
to release and be absorbed. 

Thus it was necessary to formulate it into a polymer that forms a
gelatinous mass in the stomach. The size of this mass, a concurrent meal
and the natural diurnal slowing of the GI tract at night together
provide the best conditions for absorption because of delayed passing 
through the gut. There is also a saturation effect with doses greater
than 2g not having a proportional increase in absorption. One also
wonders about the impact of 6 "gelatenous masses" in the gut at the same
time?

All the trials on the XR formulation were done with dosing with the
evening meal and I have wondered by how much this is reduced in reality
if given with a morning meal. And whether a reduction in absorption is
more than offset by an increase in compliance. In other words, is
morning metformin XR 2g better than morning regular metformin 1g (the
evening dose being forgotten?). 

I'd be interested to hear if there are actual clinical benefits like
lower HbA1cs in your patients? 

The other issue is one of side effects. Having a smaller amount of drug
released into solution in the gut at any one time might logically be
associated with less GI side effects. The trials showed no difference
between XR and regular metformin but the numbers were low. Has anyone
noticed an impact on GI side effects? 

Fran Vaughan
Pharmacist

>>> <MichaelW.Nixon at nt.gov.au> 19/04/2007 9:24 am >>>
I am finding such a lot of non-compliance amongst the Aboriginal
diabetic 
population and I'm slowly changing all my patients over to SR metformin

(up to 2gms) in the hope that there may be more compliance by a once
daily 
dose in the morning - to be had with their weetbix or porridge! - So
far 
seems to be working. Just watch the Kidneys! - Mike.

Dr Michael W Nixon
DMO Reg.  Rm 126,  Block 4, RDH
(Chair MSHR, Ethics Research Committee)
Box 40596
CASUARINA NT 0811
Ph 892 28358 Mob 0427 618 915

"Alex Hope" <wombat at octa4.net.au> 
Sent by: carpa-bounces at ozdocit.org 
18/04/2007 09:36 PM
Please respond to
Central Australian Rural Practitioners Association <carpa at ozdocit.org>

To
carpa at ozdocit.org 
cc

Subject
[CARPA] Fwd: Re: swapping to Metformin XR

Would be good to have input from a few more people on this topic.
I haven't tried it with any of my patients yet.
Alex
(scroll down for email exchange)
Dr Alex Hope

Community GP,
Ltyentye Apurte Community Government Council Health Centre,
CMB Santa Teresa,
via Alice Springs,
NT 0872.

Ph  08 8956 0911
Fax 08 8956 0910
Mobile 0408 085 143

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***********Here Followeth a  Forwarded Message***********

On 18/04/2007 at 8:18 PM Ciara.OSullivan at nt.gov.au 
<Ciara.OSullivan at nt.gov.au> wrote:

>Hi there
> 
>The recommended maximum dose of metformin XR is 2 g daily, which is 
pretty
>much in line with the total dose of standard metformin we are mostly 
using
>now.
> 
>Ideally metformin XR is taken nocte ... but this is not very practical

and
>I think we just have to compromise over this detail.
> 
>Cheers - Ciara
>
>-----Christine Connors/THS/NTG wrote: -----
>
>To: Ciara O'Sullivan/THS/NTG at NTGeMAG
>From: Christine Connors/THS/NTG
>Date: 04/16/2007 10:01AM
>cc: Alan Evans/THS/NTG at NTGeMAG, Heinz Deiter/THS/NTG at NTGeMAG, John
>Hester/THS/NTG at NTGeMAG, Louise Elliott/THS/NTG at NTGeMAG, Nick
>Tyllis/THS/NTG at NTGeMAG, russell.thompson at wynhealth.org.au, Stephen
>Brady/THS/NTG at NTGeMAG, Stephen Foster/THS/NTG at NTGeMAG, 
wombat at octa4.net.au 
>Subject: Re: swapping to Metformin XR
>
>so what is other people's experience
>will patients take the 4 tabs to make 2gm daily or do they prefer the
>usual 1gm bd?
>
>Ciara: apart from the obvious issue of big tablets, is there any
issues
>taking metformin XR as 3gm single daily dose?
>
>
>Dr. Christine Connors
>Program Director PCD
>NT Department of Health & Community Services
>Phone: (08) 8922 8218
>Fax: (08) 8922 7714
>Mobile: 0401 116 121
>email: christine.connors at nt.gov.au 
>
>
>
>
>
>
>
> Ciara O'Sullivan/THS/NTG
>
>
>Ciara O'Sullivan/THS/NTG 
>
>14/04/2007 07:31 PM
>To
>
>Alan Evans/THS/NTG at NTGeMAG, Stephen Foster/THS/NTG at NTGeMAG, John
>Hester/THS/NTG at NTGeMAG, Louise Elliott/THS/NTG at NTGeMAG, Nick
>Tyllis/THS/NTG at NTGeMAG, Heinz Deiter/THS/NTG at NTGeMAG,
>russell.thompson at wynhealth.org.au 
>
>cc
>
>Christine Connors/THS/NTG at NTGeMAG, wombat at octa4.net.au, Stephen
>Brady/THS/NTG at NTGeMAG
>
>Subject
>
>Re: swapping to Metformin XR
>
>
>
>Hi team
> 
>Metformin XR is now available in most remote clinics.
> 
>I would like to emphasise that metformin XR and standard metformin 500
mg
>tablets are equivalent and when swapping from a usual treatment dose
of
>standard metformin of 1 g bd, you need to prescribe metformin XR 4 
tablets
>daily. No down-titration is needed with subsequent up-titration.
> 
>YES!!! The metformin XR tablets are pretty big and are actually the
same
>size (but bulkier) than metformin 1 g tablets. You need to show the
>patients what they are getting as some patients are horrified and
refuse
>to swap. 
> 
>I think using metformin XR in usual treatment doses of 2 g per day is

very
>useful for patients on few other tablets. However use of metformin XR
>poses some real problems for us as clinicians; on the one hand we want
to
>provide convenient once daily medications (improves compliance) but on

the
>other hand, prescribing 4 whoppers in addition to a handful of other
>morning medications is very off putting for many patients (reduces
>compliance).
> 
>This is the doctors' s dilemma. However, the solution is not to
prescribe
>half the previous standard dose of meformin (ie swapping from
metfrormin 
1
>g bd to metformin XR 1 g od) which potentially deprives the patient
of
>useful treatment, and this is what I am seeing on a lot of the scripts
at
>the moment!
> 
>Cheers - CIara

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