On June 23, the U.S. Food and Drug Administration (FDA) approved a new pill that combines two older drugs for Type 2 diabetes. Called PrandiMet, the pill is a combination of repaglinide (brand name Prandin) and metformin (Glucophage and other brand names).
The two components of PrandiMet help lower blood glucose levels in different ways. Metformin prevents the liver from making too much glucose and makes the body more sensitive to insulin. Repaglinide stimulates the pancreas to release insulin quickly, and is used at mealtimes to help control after-meal blood glucose levels.
The approval of this new combination drug was based in part on a study of 83 people (published in Diabetes Care in 1999) that showed that repaglinide and metformin together lowered blood glucose more than either drug alone. In the study, the people randomly assigned to take a combination drug for 4–5 months had a 1.4% drop in HbA1c levels compared to nonsignificant HbA1c changes in people who took either drug on its own. The study was also double-blind, meaning that neither the researchers nor the participants knew who was receiving which drug.
However, these results were not without side effects. People who took the combination drug had a higher rate of hypoglycemia (33%) compared to those who took repaglinide alone (11%). And those who took repaglinide either alone or in combination gained weight (about 5–6.5 pounds), while the people in the metformin-only group lost weight (about 1.9 pounds).
Other concerns associated with PrandiMet include kidney and liver function; people who have kidney or liver disease should not use PrandiMet, and the FDA advises that people have their kidney function checked before starting on PrandiMet and then at least once a year while they are taking the drug. PrandiMet should also be stopped before radiologic procedures involving iodinated contrast dye and not taken for another 48 hours after the procedure. And, because it contains metformin, PrandiMet carries some risk of gastrointestinal side effects (such as diarrhea, nausea, and vomiting) and a small risk of the serious side effect lactic acidosis.
PrandiMet will be available in the second half of this year. It will come in two fixed doses—1 milligram [mg] of repaglinide with 500 mg of metformin and 2 mg repaglinide with 500 mg metformin—and is recommended to be taken two to three times a day with meals.
PrandiMet is the first Type 2 diabetes combination drug combination on the market to contain repaglinide, but several other combination drugs contain metformin. These include Janumet (sitagliptin [Januvia] plus metformin), ACTOplus met (pioglitazone [Actos] plus metformin), Avandamet (rosiglitazone [Avandia] plus metformin), Metaglip (glipizide [Glucotrol] plus metformin), and Glucovance (glyburide [Micronase, DiaBeta, and Glynase] plus metformin).