Risk of Invokana Side Effects May Outweigh Benefits: Report

A new drug safety report suggests that the high rate of infections and other side effects of Invokana may tip the balance in the risk-benefit analysis for the diabetes drug. 

In a QuarterWatch report (PDF) issued on May 6, the Institute for Safe Medication Practices (ISMP) looked at the safety and efficacy of the Johnson & Johnson diabetes drug, which has only been on the market for about two years.

Invokana was released amid concerns about side effects associated with a variety of other diabetes drugs, but appears to be linked to health risks of its own, which raise questions about whether the drug’s risks may outweigh the benefits for diabetics.

The FDA approved Invokana (canagliflozin) in March 2013, as the first in a new class of diabetes medications that inhibit a particular function of the kidney, allowing an increased amount of sugar to be excreted in the urine.

Introduced by Johnson & Johnson’s Janssen subsidiary, the drug came in the wake of heart attack concerns over the drug Avandia, bladder cancer concerns involving the diabetes drug Actos, and the beginning of pancreatic cancer concerns involving the diabetes drugs Byetta, Januvia, Janumet and Victoza.

Following two years of adverse event data, the ISMP report raises concerns over Invokana side effects and the clinical trials used to approve the medication for the market.

Adverse Events Involving Invokana Problems

During the first year after Invokana was approved, ISMP found 457 serious adverse event reports submitted to federal drug regulators, which typically only account for a small portion of the total problems associated with prescription medications on the market.

Many of the reported Invokana problems involved kidney failure, kidney impairment or problems with kidney stones, urinary tract infections, dehydration, hypersensitivity and abnormal weight loss. Janssen officials reportedly told ISMP investigators that most of those injuries are known risks that are warned about on the drug’s label, with the exception of kidney stones. However, the ISMP report questions whether the benefits provided by Invokana justify those risks.

“At the time of FDA approval, canagliflozin had not been tested in a sufficient number of patients for a long enough period of time to answer that question,” the report states. “In the face of that uncertainty about benefit was increasing evidence that canagliflozin is associated with adverse effects in appropriate clinical use.”

Clinical trials for the drug found that urogenital infections, mainly fungal, were the most frequent side effect of Invokana, with a full 14% of women and nearly 4% of men who took the drug developing fungal infections at rates as high as six times that of non-Invokana users with similar kidney and health profiles.

Looking at reports to the FDA’s adverse event reporting system, the researchers found that Invokana received more serious adverse event reports than 92% of the other drugs regularly monitored.

The ISMP report found that at the cost of those risks came very few benefits. According to the report, the Invokana clinical trials showed that the drug typically lowered levels of glycated hemoglobin (HbA1c), a primary type 2 diabetes blood sugar measurement, by about only one percent. It also caused weight loss of a mean of five to six pounds in users.

“While Janssen noted that the drug had now been tested in more than 10,000 patients, the data were still of insufficient duration to establish whether the drug had a measurable clinical benefit on the complications of Type 2 diabetes,” the report concludes. “The current data are also insufficient to address unanswered questions raised in the FDA reviews about whether long-term use might result in a steady decline in kidney function, increased risk of bone fractures, or more cardiovascular events. By contrast, we observe clear evidence of harm to some patients in terms of hypersensitivity reactions and an array of renal adverse effects.”