Reports of problems with type 2 diabetes drug Invokana (canagliflozin) have continued to increase, according to the Institute for Safe Medicine Practices (ISMP) most recent QuarterWatch for the second quarter of 2015.
“Both prescription volume and adverse drug event reports are increasing rapidly for a new class of drugs for Type 2 diabetes that lower blood sugar by causing the kidneys to excrete some circulating glucose rather than returning it to circulation,” the authors wrote. Invokana is one of those drugs in a class called “incretin mimetics.” The other two medications in the same class are Jardiance and Farxiga, which were both approved after Invokana.
Invokana Works by Blocking Reabsorption of Glucose
Invokana was the first in this new class of drugs—also called “sodium-glucose co-transporter 2 (SGLT-2) inhibitors”—to be approved by the FDA. At the time, it was marketed as a more convenient option to previous type 2 diabetes medications. Manufacturer Janssen Pharmaceuticals, in its announcement of the approval, stated that Invokana was the only “oral, once-daily medication available in the United States offering improved glycemic control while also showing reduced body weight and systolic blood pressure in clinical trials.”
The drug company went on to explain that the kidneys play an important role in balancing blood glucose levels, as most of the glucose that passes through the kidneys is reabsorbed back into the blood stream. Invokana inhibits the action of SGLT2, which is involved in the re absorption process. As a result, not as much glucose goes back into the body—some of it is flushed out with the urine.
Though this action lowers overall blood glucose levels in patients, it has also been linked with some serious side effects.
Over 5,000 Adverse Events Linked with Invokana Use
The ISMP states in their report that “despite the lack of long-term data on safety and benefits,” Invokana and other similar drugs have quickly reached widespread use. By the second quarter of 2015, Invokana had been prescribed 1.1 million times. Yet while prescriptions increased, so did the reports of problems.
Between the second quarter of 2014 and the second quarter of 2015, a total of 5,484 new cases of adverse events were reported concerning Invokana. Some of these involved diabetic ketoacidosis (DKA)—a condition in which the blood becomes to acidic. The FDA warned of a potential increased risk of this condition in patients taking Invokana and other similar drugs back in May 2015, stating that the medications could lead to DKA, “a serious condition where the body produces high levels of blood acids called ketones that may require hospitalization.” The FDA required manufacturers to add new label warnings concerning the condition last December.
The ISMP also reported that the majority of the adverse drug events associated with SGLT2 drugs are genital fungal infections. The ISMP notes that the presence of glucose in the urine and bladder “creates a favorable environment for infections,” and that without treatment, these infections can spread to the kidneys, with life-threatening results.
ISMP Question the Safety of Invokana
The ISMP also noted a particular concern with this new class of drugs and older patients, as they can be at increased risk for kidney problems to begin with. “Whether the clinical benefits of these drugs outweigh the increasing evidence of their risks remains uncertain,” the authors wrote.
Conditions associated with Invokana included DKA, genital and other fungal infections, renal toxicity, hyperkalemia, acute renal failure, and urinary tract infections.