While many patients believe that generic drugs are exact copies of their brand name brothers, the body often absorbs generic medication at a different rate, and federal regulators do not routinely disclose the slight chemical differences.
Differences between a brand name pill and its generic copy became painfully obvious to a Manhattan woman being treated for depression who spoke to the I-Team on the condition her identity be withheld. In 2007, she says she experienced vastly different results when she transitioned from Wellbutrin XL to a generic version of the pill marketed by Teva.
"What it felt like was, first thing in the morning I was getting all this medication dumped into my blood stream and it was a roller coaster ride. It just didn't feel right," she said.
It turned out the pills were not equivalent. An FDA study showed Teva's generic version released the anti-depressant chemicals at a different rate. After hundreds of patient complaints, the FDA asked Teva to pull the pill off the market in 2012.
Neither Teva, the firm that marketed the generic pill, nor Impax, the company that manufactured it, responded to emailed questions from the I-Team.
"I think a lot of people are surprised to hear that generic drugs really aren't identical to the brand name medication," said Dr. Tod Cooperman, who operates ConsumerLab.com, a website that publishes test results on health products and supplements.
The FDA considers generics to be therapeutically equivalent as long as their active ingredients are absorbed at a rate between 80 and 125 percent of the brand name pill. But the FDA does not routinely make public the exact absorption rates of generic pills. That data is called bioequivalence information.
Cooperman says doctors could avoid unnecessary suffering for their patients if they could use bioequivalence data to more finely tune dosages of generic drugs.
"If that information, that bioequivalence information, were available, as I believe it always should have been, at least your doctor will have a clue as to the differences between these medications," Cooperman said.
Sandy Walsh, a spokeswoman for the FDA, told the I-Team in an email that generic drug bioequivalence data is only released to the public after an official request under the Freedom of Information Act. She also said the test results could be partially or totally withheld out of consideration for a pharmaceutical company's trade secrets.
"Data in all drug applications is subject to FOI because it needs to be reviewed for proprietary/confidential information," Walsh wrote.
Now New York State Assemblywoman Amy Paulin, a Democrat from Scarsdale,wants to bypass the FDA with a bill that would force drug companies to share bioequivalence information or be barred from New York's drug market.
"It would require the generic company to give that same chemical make-up that they have to give to the FDA, to us the state, for us to put on a website to be available," Paulin said. "It'll help the whole country," she added.
Walsh said the FDA does not comment on pending legislation, but she cautioned against placing too many demands on companies that manufacture generics. While brand name medications require exhaustive clinical testing, generics remain relatively cheap because they can bypass expensive research and development stages.
"The spirit of the generic drug law was that the process is 'abbreviated' and does not require as much study as what is done for a brand new product," Walsh wrote.
Since Teva's version of Wellbutrin was pulled, patients using generic versions of epilepsy drugs and blood pressure pills have also complained that their generic medications are significantly different from brand names. The FDA has not made their bioequivalence data public.