Monograph: |
Glipizide
A white or almost white crystalline powder. Practically insol-
uble in water and in alcohol: sparingly soluble in acetone;
soluble in dichloromethane. It dissolves in dilute solutions of
alkali hydroxides. Store in airtight containers. Protect from
light.
Adverse Effects, Treatment, and Precautions
As for sulphonylureas in general, like glimepiride.
Interactions
As for sulphonylureas in general, like glimepiride.
Antacids. Magnesium hydroxide and sodium bicarbonate
have been reported to increase the rate of absorption, although
not the total amount absorbed, of a dose of glipizide in
healthy subjects. No such effect was seen with aluminium
hydroxide.
Pharmacokinetics
Glipizide is readily absorbed from the gastro-intes-
tinal tract with peak plasma concentrations occur-
ring I to 3 hours after a single dose. It is extensively
bound to plasma proteins and has a half-life of ap-
proximately 2 to 4 hours. It is metabolised mainly in
the liver and excreted chiefly in the urine, largely as
inactive metabolites.
A study in 12 healthy subjects indicating that hyperglycaemia
impairs the absorption of single doses of glipizide. This is
probably a result of an effect on gastric emptying and gastric
motility.
Uses and Administration
Glipizide is a sulphonylurea hypoglycaemic.
It is given by mouth in the treatment of type
2 diabetes mellitus and has a duration of ac-
tion of up to 24 hours. The usual initial dose is 2.5 to
5 mg daily given as a single dose 15 to 30 minutes
before breakfast. Dosage may be adjusted at inter-
vals of several days by amounts of 2.5 to 5 mg daily,
to a maximum of 40 mg daily. Doses larger than
15 mg daily are given in two divided doses before
meals. Modified-release formulations of glipizide
are available in some countries; one such prepara-
tion (Glucotrol XL) is given in doses of 5 to 10 mg
daily as a single dose with breakfast.
Administration. Although glipizide may be given in doses
up to a recommended maximum of 40 mg. evidence for the
benefits of high doses is scanty. A small study in patients with
type 2 diabetes mellitus found that not only did increases in
glipizide doses to more than 10 mg daily produce little or no
benefit, but that the higher doses were associated with re-
duced rises in plasma-insulin concentrations and a lesser re-
duction in plasma-glucose concentrations. There is,
however, some evidence that glycaemic control and insulin
sensitivity can be improved by the use of a modified-release
rather than a conventional formulation of glipizide.
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