Two consumer-advocacy organizations are criticizing a Food and Drug Administration investigation into a generic version of a popular, once-daily dose antidepressant, calling the regulatory agency’s review “inadequate.”

White Plains-based ConsumerLab.com and The People’s Pharmacy, of Durham, N.C., said a determination by FDA that a generic version of Wellbutrin XL 300, manufactured by Impax Laboratories and distributed by Teva Pharmaceuticals, was safe was based on information from a lower dose of the drug.

Calling the FDA’s findings disappointing, ConsumerLab.com and The People’s Lab said there was no evidence that the FDA evaluated the generic drug for safety and effectiveness.

“For the FDA to say that it has reviewed the safety and efficacy of this product is not correct,” said Dr. Tod Cooperman, president of ConsumerLab.com.

“The FDA is misleading the public by publishing a positive review which actually provides no data for the 300 milligram product – the strength about which people are complaining,” said Joe Graedon of The People’s Pharmacy (www.peoplespharmacy.com).

The FDA undertook its investigation after receiving complaints that patients taking the branded product experienced a loss of effectiveness when switched to the generic pill. Further, patients reported new onset or worsening of side effects.

In reporting its findings today, the FDA said the generic version, marketed as Budeprion XL 300 milligrams, was “safe and effective.”

Further, the government said the generic version was equivalent, and therefore interchangeable with, Wellbutrin XL 300.