SULFONYLUREAS, REPAGLINIDE, AND
NATEGLINIDE
WORKING
These are oral medications
that bind to receptors on the beta cell, causing it to release insulin. The released insulin then lowers the
glucose levels.
Tolbutamide, chlorpropamide,
acetohexamide, and tolazamide are referred to as first-generation sulfonylureas, and, with the exception of
tolbutamide, are rarely used these days. The newer, second-generation drugs are glyburide, glipizide,
glimepiride, and gliclazide, and these are commonly used. They vary in their duration of effect and how they
are removed from the body.
Nateglinide and repaglinide
are chemically different from the sulfonylureas, but they work the same way. Their effect lasts only a few
hours, and so they are commonly given before each meal.
SIDE EFFECTS
The main side effect of these
medicines is that they can cause hypoglycemia (low blood glucose reactions) if a person takes the prescribed
dose and does not eat enough. The risk of hypoglycemia with the sulfonylureas is higher in the elderly and those
with kidney failure. For these groups, it is better to use lower doses and the fast-acting drugs—glipizide,
repaglinide, and nateglinide. Tolbutamide is also an inexpensive option that can be given two or three times a
day and has a low risk of hypoglycemia.
People taking these medicines
tend to gain some weight with time. The reasons for the weight gain are not clear—one possibility is that at
times the medicine causes low glucose levels, causing hunger so that the person overeats. Also, perhaps if the
person sees that the medicine controls the glucose level well, he or she might be tempted to eat more, thinking
that there will not be any consequences.
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