An investigational study has been launched by federal drug regulators to look into generic versions of the blood pressure drug Toprol XL, following thousands of complaints received from doctors and patients, which are not being seen among users of the brand-name drug.
The FDA has received reports of problems involving generic metoprolol succinate, which suggest that the medication may be less effective and causes more side effects than AstraZeneca’s Toprol XL.
All generic drugs are required to be bioequivalent to the brand-name products they imitate; meaning they should be just as effective and have the same risk of side effects.
On April 16, the FDA announced it will fund a number of generic Toprol XL studies to test whether the generic versions are actually equal to the brand name drug. The Department of Health and Human Services (DHHS) has indicated that it is taking applications from researchers seeking a grant to conduct the study to its requirements.
So far, the FDA has been unable to pin down on its own the cause of the complaints or to confirm that there is some difference in the generic Toprol XL products manufactured by Actavis, Dr. Reddy’s Laboratories, Mylan Inc. and Wockhardt Ltd.
“Therapeutic inefficacy and adverse events have been reported by physicians and patients switching from brand to generic metoprolol extended release products,” the grant application states. “The FDA continues to monitor the FDA Adverse Event Reporting System (FAERS) for reports relating to currently marketed metoprolol products. However, based on current data available to the agency, it is difficult to draw definitive conclusions about the cause of the concern.”
Since March 2009, the FDA has received more than 3,400 adverse event complaints involving generic Toprol XL. However, the reports do not identify which generic versions are causing the problems; they only state that they are not the brand-name product by AstraZeneca.
One of the manufacturers, Wockhardt, Ltd., manufactured generic Toprol XL at a facility in India that was banned from shipping drugs to the U.S. in November 2013, after the FDA found out that its workers were providing false information on quality control tests. The facility was also found to be unsanitary. Before the factory was banned from sending drugs to the U.S., it accounted for a quarter of all generic Toprol XL.
Novartis also used to manufacture the drug, but stopped following a massive recall in 2008 that affected about 6 million bottles. The recall was issued after the FDA declared that the drug did not meet the agency’s quality standards.