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C H A P T E R 3 8 Agents to control blood glucose levels

TABLE 38.3

DRUGS IN FOCUS Other oral hypoglycaemic agents (continued)

Drug name

Dosage/route

Usual indications

Other oral hypoglycaemic agents (continued) Incretin mimetic exenatide (Byetta)

5 mcg by SC injection within 60 minutes before morning and evening meals; may be increased to 10 mcg b.d. after 1 month

Adjunct to diet and oral agents to improve glycaemic control in people with type 2 diabetes

Sodium-glucose co-transporter inhibitors canagliflozin (Invokana)

100–300 mg/day PO

Adjunct to diet and exercise to improve glucose control in people with type 2 diabetes, as monotherapy or combined with other agents Adjunct to diet and exercise to improve glucose control in people with type 2 diabetes, as monotherapy or combined with other agents Adjunct to diet to lower blood glucose in type 2 diabetes; in combination with insulin or sulfonylureas to control blood sugar in people whose diabetes cannot be controlled with either drug alone Adjunct to diet to lower blood glucose in type 2 diabetes; in combination with insulin or sulfonylureas to control blood sugar in people whose diabetes cannot be controlled with either drug alone

dapagliflozin (Forxiga)

10 mg/day PO

Thiazolidinediones pioglitazone (Actos)

15–30 mg/day PO as a single dose; use caution with hepatic impairment

rosiglitazone (Avandia)

4–8 mg/day PO as a single dose; use caution with hepatic impairment

with the body’s glucose controls in a number of ways, including affecting insulin release, decreasing insulin resistance or altering glucose absorption from the GI tract and release of glucose by the liver. They often are combined with a sulfonylurea to increase glycaemia control. S ulfonylureas The sulfonylureas bind to potassium channels on pan- creatic beta cells. They may improve insulin binding to insulin receptors and increase the number of insulin receptors. They are also known to increase the effect of antidiuretic hormone on renal cells. They are effec- tive only in people who have functioning beta cells. They are not effective for all diabetics and may lose their effectiveness over time with others. Sulfonylureas are further classified as first-generation or second- generation sulfonylureas. All of the sulfonylureas can cause hypoglycaemia. First-generation sulfonylureas The first-generation sulfonylureas included chlorpropa- mide and tolbutamide. However, these drugs are no longer used in Australia and New Zealand. The first-generation sulfonylureas were associated with an increased risk of cardiovascular disease and death in a somewhat controversial study. They are now

thought to possibly cause an increase in cardiovascular deaths. Second-generation sulfonylureas The second-generation drugs include glibenclamide ( Daonil , Gliben , Glimel and others), gliclazide ( Dia- micron, Glyade ), glimepiride ( Amaryl ) and glipizide ( Melizide , Minidiab ). See Table 38.3 for usual indica- tions for each drug. Second generation sulfonylureas have several advantages over the first generation drugs, including the following: • They are excreted in urine and bile, making them safer for individuals with renal dysfunction. • They do not interact with as many protein-bound drugs as the first-generation drugs. • They have a longer duration of action, making it possible to take them only once or twice a day, thus increasing compliance. Glimepiride is a much less expensive drug than most of the other sulfonylureas, which has advantages for some people. Prescribers may try different agents (first- or second-generation drugs) before finding the one that is most effective for a given person. Therapeutic actions and indications The sulfonylureas stimulate insulin release from the beta cells in the pancreas (see Figure 38.3). They improve