Ask the Pharmacist

Q: My doctor put me on a medication for my diabetes called Invokana. I seem to keep hearing negative things about it in the media. Should I be concerned?

A: Invokana (canaglifozin) and its “sister” drugs, Jardiance (empaglifozin) and Forxiga (dapaglifozin), first entered the Canadian marketplace in mid-2014 and have found themselves in the middle of a media storm from pretty much that point.

Initially, the class of drugs known as the sodium-glucose co-transporter 2 inhibitors (SGLT2 inhibitors), was eagerly greeted as a novel new way to help Type-2 diabetics get a better handle on their blood sugars. These drugs work differently than other diabetic medications in that they cause more of the sugar in your blood stream to be incorporated into your urine where it is eliminated from your body rather than being reabsorbed back into the blood stream as it normally is.

As a class, they were only modestly effective at lowering your sugars (on average they would reduce your A1C, which is a measure of the three-month average of your blood sugars, by about one per cent), but they had the potential to lower your weight and blood pressure as well without greatly increasing the risk of your blood sugars dropping too drastically.

On the down side, they were known to increase your risk of bladder and genital yeast infections, as well as cause you to urinate more frequently. Overall, they were generally considered to be fairly safe drugs when they first entered the market. However, with the recent release of the sixth “Black Box” warning about these drugs from the FDA in the United States, it may be time to reassess whether these drugs with their minor benefits are worth the risks they seem to pose.

The latest warnings indicate that Invokana seems to increase the risk of diabetics having to undergo an amputation while they are on the drug. Diabetics, in general, have a higher risk of this type of surgery than the general population due to the degenerative effects of elevated blood sugars on the blood vessels within our body.

However, patients on Invokana seem to require an amputation about twice as often as regular diabetics (six per 1,000 people per year on Invokana versus three per 1,000 taking other diabetic drugs or treating with diet alone), mainly of the toe or mid-foot region.

While this effect has still only been seen with Invokana, there are very real concerns that fellow SGLT2 inhibitors, Forxiga and Jardiance, might increase this risk as well. Patients currently taking these drugs are being told to notify their family practitioner immediately if they experience foot pain or tenderness or sores and ulcers on their feet as they do their daily foot inspection.

Experts are also advising that those who may be at a greater risk of requiring an amputation (such as those who have previously had one, or also suffer from peripheral neuropathy, peripheral vascular disease or have a current foot ulcer), to consult their physician as to whether they should consider changing their medication regimen.

However, given the concerns about these drugs prior to this, we may be reaching a point where all patients might be justified in consulting with their physician as to whether they should stay on these drugs for the long-term even if they seem to be tolerating them well.

In the past couple of years, ongoing monitoring has linked the various members of this class to other significant and potentially life-altering side effects, such as ketoacidosis (a metabolic state in which the acidity of your blood can rise quickly and can, in extreme cases, be fatal), hyperkalemia (an increase in the amount of potassium in your body which can lead to heart rate irregularities), a decrease in bone density and subsequent increase risk of suffering a fracture, an increased risk of having your kidneys injured, and a possible link to bladder cancer.

No drug comes without some degree of downsides but we are probably at the point where we can debate whether these three drugs with their modest benefits really justify the risks, rare may they be, that they seem to pose.

We would strongly suggest that no one suddenly stop taking these drugs as elevated blood sugars pose their own far more common risks (eye damage, cardiovascular risk, kidney disease, nerve pain), but it would be prudent upon your next appointment with your physician to get his or her opinion as to whether these drugs are still the best way to control your diabetes.

For more information about this or any other health-related questions, contact the pharmacists at Gordon Pharmasave, Your Health and Wellness Destination. Also check the website at www.gordon-pharmasave.com/ and the Facebook page at www.facebook.com/GordonPharmasave/?fref=ts