An Advertisement for Invokana

As I turned the cover page of the February 8-14, 2014 issue of The Lancet expecting to find the table of contents, I found instead an 8-page advertisement for Invokana, which urged me to Envision New Possibilities. Invokana, the ad said, is the #1 branded therapy prescribed by endocrinologists when adding or switching non-insulin type 2 diabetes medications.  As it happens, I was working on the March 2014 issue of Treatment Guidelines from The Medical Letter, which is on Drugs for Type 2 Diabetes. So, I thought, let’s see what we have to say about that.

Speaking truth to the power of the pharmaceutical industry, its journal ads and drug reps, is the reason for being of The Medical Letter. We go to great lengths to maintain our independence from the industry. We do not have advertisements. We do not accept grants, gifts, or donations. We do not sell bulk reprints to pharmaceutical manufacturers.

So we can look at Invokana with clear eyes. Its generic name is canagliflozin, and it is one of 2 SGLT2 (sodium-glucose co-transporter 2) inhibitors currently on the market in the US. The other, called dapagliflozin (Farxiga), was only recently approved by the FDA (it was reviewed in the February 17 issue of The Medical Letter); its approval was delayed because of concerns about an increased incidence of bladder cancer in patients treated with the drug in clinical trials. SGLT2 inhibitors are different from other drugs for diabetes: rather than acting on insulin in one way or another, they decrease renal glucose reabsorption and increase urinary glucose excretion, reducing blood glucose levels that way instead.

Our article on Drugs for Type 2 Diabetes includes a table listing the A1C reductions, advantages, and adverse effects of all the drugs used to treat the disorder. At a glance, we can see that one disadvantage of SGLT2 inhibitors is that they typically reduce A1C less than metformin, sulfonylureas, thiazolidinediones, or GLP-1 receptor agonists. Their advantages are that they cause weight loss rather than the weight gain associated with use of some of the other agents, and they do not cause hypoglycemia. They do have one unique adverse effect: they cause genital mycotic infections in both men and women (all that sugar in the urine), which some patients may find intolerable.

The Medical Letter, in a nutshell, does not share the advertisement’s enthusiasm for Invokana. We emphasize instead the use of metformin as the first-line agent for type 2 diabetes, and if metformin does not achieve the desired goal, we recommend adding one of several other drugs, but not either one of the SGLT2 inhibitors.  They are less effective, and their long-term safety is unknown. The advertisement for Invokana contains a lot of information in its 8 pages, but it won’t tell you that.

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  1. And that is one of the reasons why I continue to subscribe to The Medical Letter. Thanks for honest, science-based reports, not advertisements.

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