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Drug Investigation:Toprol XL vs. Generic Metoprolol Succinate Extended-release (ER) Tablets
Initial Posting: 3/17/08 Last Update: 12/31/08
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Background: Toprol XL is approved for the treatment of high blood pressure and other cardiovascular disorders including angina pectoris and stable but symptomatic forms of heart failure. Toprol XL is also used to reduce the occurrence of migraine headache. It is a beta-1-selective (cardioselective) adrenoreceptor blocker. Its generic form, metoprolol succinate extended-release tablets, first became available in November of 2006 in the 25 mg strength, followed by additional strengths (50 mg, 100 mg, and 200 mg) in July and August 2007. Toprol XL and its generic forms are expected to provide a controlled and predictable release of metoprolol for once-daily administration.
Toprol XL has been one of the most popular medications for controlling blood pressure and arrhythmias. Prior to the launch of generics, annualized sales of the most popular strength -- 50 mg -- was $640 million; sales of the 25 mg strength was about $300 million, and the 100 and 200 mg strengths together had sales of $778 million according to IMS Health.
Problems Reported with Generic Versions of Metoprolol Succinate Extended-release: A large number of complaints have been posted for generic versions of Toprol XL. These complaints generally focus on one or more of the following:
a dramatic increase in blood pressure
an increase in heart rate and ectopic beats
side effects such as nausea, dizziness, hives and headaches (including migraine)
Although there are known side-effects with Toprol XL, these, other than dizziness and itching, differ from those being reported after a switch to a generic. In particular, patients taking the generic are reporting an increase in blood pressure and heart rate while a known side-effect of Toprol XL is a slowing of the heart rate (bradycardia). The common side effects of Toprol XL, as noted on its package insert, are tiredness (10%), dizziness (10%), depression (5%), diarrhea (5%), pruritus (itching) or rash (5%), shortness of breath (3%), and bradycardia (slow heart rate) (3%).
Perhaps most striking about the consumer complaints is that problems generally stopped when medication was switched back to Toprol XL. The increase in blood pressure and heart rate reported by some suggest that the generics they used are not as effective as the original, possibly not providing high enough drug levels throughout the day.
Below are examples of complaints reported by users of generic metoprolol succinate received by ConsumerLab.com or posted at www.PeoplesPharmacy.com:
"After being on TOPROL XL for almost a year, I was switched to the generic [25 mg]â€¦ After being on it for less than two weeks, my BP started fluctuating toward the high end at different times of the day. After talking to my doctor, he wrote me a D.A.W. [Dispense as Written] order for TOPROL XL, and though I had to pay more, my BP became balanced throughout the day."
"My doctor prescribed Toprol-XL several years ago to control hypertension. All went well. Last week my pharmacist refilled my prescription with generic metoprolol succinate. Within two days my blood pressure was sky high--190/100. This has never happened before, so there may be a problem with this generic for Toprol-XL."
"My employer's drug service replaced Toprol XL with the generic equivalent in Jan 2007 and I used it until July-Aug 2007. During that time I had a number of blood pressure tests which showed my pressure rising for no apparent reason. Not to life-threatening levels, but noticeable. Late in 2007, I switched back to Toprol XL and the latest tests, after about 3 months, are back to normal low readings."
"In 2004, my GP prescribed Toprol XL (50 mg daily) for my stage 3 hypertension and migraine headaches. It has worked perfectly; my headaches have been virtually nonexistent and my BP has been in the normal range. Caremark refilled my last prescription with Metoprolol Succinate (without checking with my physician), which I have started taking. I am now experiencing terrible, unrelenting headaches, but have not yet had an opportunity to have my BP checked."
The 50 mg and 25 mg strengths have been most commonly mentioned in the complaints. Eon Labs or its parent Sandoz, which specifically markets these two strengths, has also been identified in several of the complaints. Other strengths and companies have not been commonly mentioned.
If you would like to report a problem with a generic drug, please let us know. Click here.
In January 2009, the manufacturer of four strengths of generic Metoprolol Succinate ER tablets issued a recall due to manufacturing problems. In August 2008, the U.S. FDA sent a Warning Letter to another manufacturer of Metoprolol Succinate ER tablets regarding violations in manufacturing -- resulting in later recalls but with little public announcement. See the Updates section of the report for more information.