GLUCOVANCE combines glyburide and metformin hydrochloride, two antihyperglycemic
agents with complementary mechanisms of action, to improve glycemic control
in patients with type 2 diabetes.
Glyburide appears to lower blood glucose acutely by stimulating the release
of insulin from the
pancreas, an effect dependent upon functioning beta cells in the pancreatic
islets. The mechanism by which glyburide lowers blood glucose during long-term
administration has not been clearly established. With chronic administration
in patients with type 2 diabetes, the blood glucose lowering effect persists
despite a gradual decline in the insulin secretory response to the drug. Extrapancreatic effects
may be involved in the mechanism of action of oral sulfonylurea hypoglycemic
drugs.
Metformin hydrochloride is an antihyperglycemic agent that improves glucose
tolerance in patients with type 2 diabetes, lowering both basal and postprandial
plasma glucose. Metformin hydrochloride decreases hepatic glucose production,
decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.
Pharmacokinetics
Absorption and Bioavailability
GLUCOVANCE
In bioavailability studies of GLUCOVANCE 2.5 mg/500 mg and 5 mg/500 mg, the
mean area under
the plasma concentration versus time curve (AUC) for the glyburide component
was 18% and 7%,
respectively, greater than that of the Micronase
brand of glyburide coadministered with metformin.
The glyburide component of GLUCOVANCE, therefore, is not bioequivalent to Micronase.
The metformin component of GLUCOVANCE is bioequivalent to metformin coadministered
with
glyburide.
Following administration of a single GLUCOVANCE 5 mg/500 mg tablet with either
a 20% glucose solution or a 20% glucose solution with food, there was no effect
of food on the Cmax and a relatively small effect of food on the AUC of the
glyburide component. The Tmax for the glyburide component
was shortened from 7.5 hours to 2.75 hours with food compared to the same tablet
strength
administered fasting with a 20% glucose solution. The clinical significance
of an earlier Tmax for
glyburide after food is not known. The effect of food on the pharmacokinetics
of the metformin
component was indeterminate.
Glyburide
Single-dose studies with Micronase
tablets in normal subjects demonstrate significant absorption of
glyburide within one hour, peak drug levels at about four hours, and low but
detectable levels at
twenty-four hours. Mean serum levels of glyburide, as reflected by areas under
the serum
concentration-time curve, increase in proportion to corresponding increases
in dose. Bioequivalence
has not been established between GLUCOVANCE and single ingredient glyburide
products.
Metformin hydrochloride The absolute bioavailability of a 500 mg metformin
hydrochloride tablet given under fasting conditions is approximately 50-60%. Studies using single oral doses of metformin
tablets of 500 mg
and 1500 mg, and 850 mg to 2550 mg, indicate that there is a lack of dose proportionality
with increasing doses, which is due to decreased absorption rather than an
alteration in elimination. Food decreases the extent of and slightly delays
the absorption of metformin, as shown by approximately a 40% lower peak concentration
and a 25% lower AUC in plasma and a 35-minute prolongation of time to peak
plasma concentration following administration of a single 850 mg tablet of
metformin with food, compared to the same tablet strength administered fasting.
The clinical relevance of these decreases is unknown.
Glucovance
Pregnancy
Metabolism and elimination
Patients with type 2 diabetes
Hypoglycemia
Mechanism of action
Metformin hydrochloride
Information for patients
Drug interactions
Overdosage
Glipizide (glucotrol)
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