Can You Givr Me Some Informationreviewsfda Info on Impax Products

By Carina Storrs
HealthDay Reporter

WEDNESDAY, Dec. v (HealthDay News) -- People taking the antidepressant Wellbutrin now take 1 less pick for a generic version of the drug.

In October, the U.S. Food and Drug Administration recommended that generic Wellbutrin, or bupropion, made by Impax Laboratories and distributed by Teva Pharmaceuticals, be taken off the market, and Impax and Teva have agreed to stop shipping the drug.

The decision is based on an FDA study that found that the extended release (XL) form of bupropion -- Budeprion 40 -- at the 300 milligram (mg) dose was non bioequivalent to brand-proper name Wellbutrin XL at the same dose, suggesting that it may not be equally safe and effective.

The written report was published December. 5 in the New England Journal of Medicine.

Four other manufacturers brand bupropion XL in 300 mg tablets, and patients tin nonetheless get their prescription filled with these products.

"The other four generic versions of 300 mg extended-release bupropion tablets are non affected by FDA'southward recent announcement," said FDA spokesperson Sandy Walsh.

Although the agency stated that lack of bioequivalence might only employ to the Impax/Teva product because of its unique formulation, the agency is requesting that the other four manufacturers submit bioequivalence data to the agency by March 2013.

"This kind of consequence puts a cloud over all of the generic XL [forms of bupropion]," said Dr. David Hellerstein, a professor of psychiatry at Columbia University Medical Center, in New York City.

Companies including Impax/Teva also make a bupropion Xl in 150-mg tablets, which are also not afflicted by the FDA decision.

But even before the FDA determination, Hellerstein avoided any kind of generic bupropion XL. "Patient would mutter that generic XL is not the same equally make-name 40 -- it wears off sooner, it has more side effects," he said. "I tell patients not to go to Forty unless you're committed to taking brand proper name."

For patients who want a less expensive generic, he recommends sustained release (SR) because at that place does non seem to be a clinical difference between the brand name and generic versions in that form. SR has to be taken twice a day, while Xl is taken once a solar day.

"If it were me and I could beget it and/or my insurance visitor allowed me to take it, I would err on the side of caution and have the brand name until the generics were proven at the college doses to be bioequivalent," said Dr. Sheldon Preskorn, a professor of psychiatry at Academy of Kansas School of Medicine-Wichita.

The FDA decided to study the bioequivalence of bupropion Forty 300 mg made by Impax/Teva to the brand-proper name counterpart because of adverse events that had been reported to the agency since the generic was approved in 2006.

"The adverse issue reports we got included loss of antidepressant issue and, in some instances, worsening of depression symptoms, following a switch from the brand name to a generic product," Walsh said.

Some patients also reported that agin effects associated with bupropion, including headache, fatigue and feet, got worse after switching to Impax/Teva'south generic version, Walsh added.

Virtually half of these patients said their depressive symptoms and adverse events improved subsequently switching back to Wellbutrin Xl 300 mg, according to the FDA.

"Relapsing of major depression is non inconsequential," Preskorn said. "Major depression causes bug with social operation, work operation and some level of a suicide risk."

For the bioequivalence study, the FDA measured the level of Wellbutrin and bupropion Forty 300 mg in the blood of 24 healthy adult volunteers over the course of the 24-hour interval afterward taking the medications.

The FDA requires the level of generic drug absorbed in the blood to be, on boilerplate, within eighty and 125 percent of the level of the brand-name version. Yet the range of assimilation of bupropion XL was but between 77 and 96 percent of the level of Wellbutrin.

The departure in blood concentration between Wellbutrin and bupropion in this study could explain the clinical difference in safety and effectiveness, Preskorn said. "If the concentration is substantially lower or higher, then your concern would be reduced efficacy or greater likelihood of off-target effects," he said.

Although it is unclear why but the generic Forty in 300-mg tablets and non in 150-mg tablets, or simply the Impax/Teva version of the 300-mg tablets, would lack bioequivalence, it could be because college doses of the drug have trouble dissolving in the gastrointestinal tract, Preskorn said.

The FDA approved the generic versions of Wellbutrin Forty based on the studies demonstrating bioequivalence at the lower, 150-mg dose.

Typically the FDA recommends that makers of generic drugs exam the blood concentration of the drug at the highest dose and and so extrapolate bioequivalence data for the lower doses based on these findings.

Nonetheless, in the case of bupropion, the FDA granted a waiver to companies to test the lower dose because of concern that the college dose could cause seizures in the volunteers, Walsh wrote.

Either way, extrapolating information about safety and efficacy from one dose is usually appropriate, said Dr. Sidney Wolfe, manager of the health inquiry group at Public Denizen, a nonprofit consumer advocacy organization based in Washington, D.C.

"For most drugs, there is such a wide departure between the amount that works and the amount that causes trouble that checking out every single dose is not necessary," he said.

Still bupropion might exist an exception. Ever since it entered the market in 1985, it was known at that place was a fine line betwixt antidepressant effect and seizure adventure, Wolfe said. The FDA knows which drugs have this type of narrow therapeutic window, and for them it might have been improve to check out all the doses, he added.

Copyright © 2012 HealthDay. All rights reserved.

References

SOURCES: Sandy Walsh, Office of Public Affairs, U.Due south. Food and Drug Administration; David Hellerstein, Thou.D., professor, clinical psychiatry, directory, medical communications, Columbia Academy Medical Eye, New York City; Sheldon Preskorn, G.D., professor, psychiatry, chief science officer, clinical trial unit, University of Kansas School of Medicine-Wichita; Sidney Wolfe, M.D., director, wellness research group, Public Citizen, Washington, D.C.; December. v, 2012, New England Journal of Medicine

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