Yes, I like
to prescribe metformin in my patients: But what is the dose &side effects??
Dosage and side effects ??
Metformin is available as 500, 850 and 1,000 mg tablets with a target dose of
1,500-2,550 mg / day.
Metformin has a dose dependent absorption
in humans and its bioavailability is
limited to 50-60 % because the amount
available may result from pre
systemic clearance or binding to the intestinal wall.
Therapeutic
regimens of metformin administration
are not well standardized and its dose should probably be adjusted according
to the patient’s BMI and insulin
resistance .
For example
it was demonstrated that nonobese women with PCOS respond better than obese women to metformin treatment
at a dosage of 1,500 mg/ day
for 6 months Nonobese women in fact showed a statistically significant decrease
in serum androgen level and fasting insulin level and also an improvement
in menstrual cyclicity . Moreover
it is possible that women
who did not respond to
metformin 1.5 g dose per day
might show clinical changes
if the dose is increased to 2 g.
Common side effects are gastrointestinal such as diarrhea nausea vomiting bloating abdominal discomfort flatulence and unpleasant metallic taste in the mouth.
Lactic acidosis
and hypoglycemia are very rare.
To reduce
these side effects. It is recommended to
start metformin with a low dose
and then gradually increase
within a period of 4-6 weeks.
Why Creatinine
estimation on 6 monthly basis while on Met RY?: In cases of IGTT renal function
may be impaired. As such if a man or woman is on long term met therapy then
before initiation of metformin ,serum creatinine estimation seems prudent
thereafter on 6 monthly basis .
.Metformin may cause vitamin B12
malabsorption and so every
patient should be monitored for signs and symptoms
of vitamin B 12 deficiency numbness paresthesia macroglossia
behavioral changes and pernicious anemia.
Metformin prescription should be avoided in women with renal
insufficiency congestive heart failure
sepsis or hepatic dysfunction .Therefore testing
of hepatic and renal function is
necessary in advance of prescription and thereafter yearly testing
is indicated.
However it has been
demonstrated that metformin use
for up to 6 months dose not adversely
affect renal or liver function
in a large sample
of PCOS women even
those with mildly abnormal
baseline hepatic parameters .The length of metformin
treatment in PCOS patients
is not standardized but data present in literature showed that after a
long term metformin
treatment drug suspension is related
to a quick reversion of its beneficial effect
on peripheral insulin
sensitivity. The insulin resistance is associated
with
Abnormally
low levels of DCI in urine
plasma and insulin target tissues
Vote for MI :: NOTA to DCI::How many members believe that
“ PCO is often associated with excessive MI
urinary excretion : . Intracellular
MI deficiency in
insulin sensitive tissues In the contrary more recently Nestler
proposed that in a woman with
PCOS an initial genetic
or environmental insult causing
insulin resistance leads to
a compensatory hyperinsulinemia.
The latter induces a defect that increases renal
clearance of DCI and this
lead to a reduction in
circulating DCI and its availability to tissue. The consequence is an intracellular deficiency
of DCI and of DCI – IPG a mediator of insulin action .Diminished
release of DCI IPG in response
to stimulation by insulin results
in a further decrease in insulin
sensitivity . Moreover
defective DCI- IPG release
in response to insulin could be due to a qualitative
defect in the insulin signaling mechanism that
activates DCI IPG mediator
release from the membrane there may
be a primary defect in the union
of the insulin receptor B unit to the G protein or a defect
in G protein activation of phospholipase.
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