The gliptins are a promising new class of drugs that block the enzyme known by the catchy name dipeptidyl peptidase 4 or DPP-4. They include two drugs, vildagliptin (proposed trade name Galvus) from the Swiss pharamaceutical giant Novartis and sitagliptin phosphate (proposed trade name Januvia) from an American company, Merck.
By inhibiting DPP-4 these drugs raise the level of the glucagon-like peptide-1 (GLP-1) hormone that our bodies release in our stomachs and intestines when we eat. GLP-1 causes the pancreas to produce more insulin and at the same time inhibits the liver from producing glucose.
The gliptins are theoretically similar to Byetta and its cousins. Those drugs are analogs of GLP-1 that do their work much longer than naturally occurring GLP-1.
But there are huge differences between the gliptins and the GLP-1 analogs. The big pluses of the gliptins are that they greatly reduce A1C levels, have few side effects, work well with existing diabetes drugs, and especially that you will be able to take them as a once-a-day pill, rather than by the injections that the GLP-1 analogs require.
Still, the clinical trials of the gliptins showed one big disappointment. They don’t cause much if any weight loss. The biggest weight claim was a loss of 1.5 kg (3.3 pounds) after 52 weeks on Januvia.
“The DPP-4 inhibitors don’t appear to have much effect on weight,” Dr. Tina Vilsboell of Genofte University Hospital in Copenhagen, Denmark, told the ADA convention in an oral presentation. “We don’t know why that is.”
Both Galvus and Januvia have completed Phase 3 trials and are pending approval from the Food and Drug Administration. Analysts expect the FDA to act on them later this year or early next year. A June 22 article in The New York Times says that analysts expect Galvus and Januvia as well as Byetta to become “blockbuster drugs” with annual sales of more than $1 billion.
At the just concluded 66th Scientific Sessions of the American Diabetes Association in Washington that I attended, the dozens of presentations and posters on these drugs put as good a face on the weight issue as possible. It is true than any drug that is weight neutral like these has a big advantage over the vast majority of diabetes drugs that cause us to gain weight.
But weight is such a big issue with 80 to 90 percent of those of us with type 2 diabetes, that Byetta and its GLP-1 cousins are much more exciting to me. My guess is that Byetta will be coming to dinner a lot more than Galvus and Januvia together.
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