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Sulfonylureas
Sulfonylureas represent
the oldest class of oral antidiabetic drugs, which have been used
since the 1950s. One first generation drug is still used (Chorpropamide)
and there are several second-generation drugs. These may be
prescribed as an add-on to metformin, but use has been decreasing,
possibly due to the availability of newer agents and concern about
cardiovascular event risk, weight gain, and hypoglycemia. These
medications tend to be less expensive and recent trials exonerating
glimepiride of excess cardiovascular risk suggest continued value in
consideration.
Available forms:
Chlorpropamide (Diabinese®)
Glipizide (Glucotrol®, Glucotrol XL®)
Glyburide (Micronase®, Glynase®, Diabeta®)
Glimepiride (Amaryl®)
Indications for Use
Adjunct to diet and
exercise to improve glycemic control in adults with type 2 diabetes.
Mechanism of Action
Stimulates beta cells of
the pancreas to release more insulin. In addition, there may be a
lowered clearance of insulin, resulting in sustained insulin levels.
Side effects may
include: hypoglycemia, weight gain, hunger, upset stomach, skin
reactions, and increase in risk for cardiovascular events.
Meglitinide Analogs
Available Forms
Nateglinide (Starlix®)
Repaglinide (Prandin®)
Indications of Use
As an adjunct, along
with diet and exercise, to attain glycemic control for patients who
have type 2 diabetes.
Mechanism of Action
The meglitinide analogs
increase calcium movement through calcium ion channels in the
pancreatic β cells, and the increased intracellular calcium
stimulates the release of insulin. This class is considered a
shorter-acting drug that should be taken before meals. These tend to
be more expensive than sulfonylureas with a similar clinical
efficacy profile.
Side effects may include
hypoglycemia, although there is less of a risk of this than there is
with sulfonylureas.
α-Glucosidase
Inhibitors
This class of drug slows
down or blocks the breakdown of carbohydrates, thereby slowing the
absorption of glucose into the bloodstream. It should be noted that
α-glucosidase inhibitors are not mentioned in the American Diabetes
Association’s 2019 Standards of Care or in recent authoritative
reviews as a first-, second- or, third-line treatment for type 2
diabetes. There are significant adverse effects such as diarrhea and
flatulence which can limit patient acceptance. The efficacy of
acarbose and miglitol are both similar to α-glucosidase inhibitors.
Available forms:
Acarbose (Precose®)
Miglitol (Glyset®)
Mechanism of Action
These drugs work when
glucose absorption is delayed, post-prandial glucose is lowered, and
the metabolism of sucrose to glucose and fructose is inhibited.
Dopamine-2 Agonist
Available forms:
Bromocriptine (Cycloset®, Parlodel®)
Mechanism of Action
While the exact blood
sugar lowering mechanisms of the dopamine-2 agonists is not fully
understood, this medication is used mainly in Parkinson's Disease.
In type 2 diabetes the doses are lower , but may “reset an
abnormally elevated hypothalamic drive” in order to decrease plasma
glucose, free fatty acids and triglycerides in patients with insulin
resistance. The result is the ability to lower blood sugar levels
through a reduction in glucose production by the liver.
These medications include bromocriptine, and are well-tolerated, and
have the potential to reduce cardiovascular event rates.
Bile
Acid Sequestrants (BAS)
Available form:
Colesevelam (Welchol®)
Mechanism of Action
The
cholesterol-lowering bile acid sequestrant (BAS) Welchol can also
help to lower blood sugar levels in patients with diabetes, though
the mechanism is not well-understood. This medication may be
considered as safe in patients with liver conditions as it is not
absorbed.
Side effects may include constipation and flatulence. |
