Teva is still fighting to keep generic versions of its blockbuster multiple sclerosis drug Copaxone off the market, with its seventh citizen’s petition asking the FDA to mandate that any ANDA on the product undergo extra levels of bioequivalence testing.

In the petition, dated July 2, the Israeli drugmaker argues that any Copaxone (glatiramer acetate) generics must undergo full-scale clinical trials and use the same gene expression markers and biological pathways in demonstrating sameness to the reference product. Doing otherwise would invite a similar but not identical generic that could be dangerous to public health, Teva says. The company said it had included new scientific data on gene expression in the petition.

Ordinary pharmacokinetic studies to determine generic equivalence aren’t enough for drugs like Copaxone that hydrolyze locally, Teva said.

The company originally had requested the testing mandate as an amendment to its NDA on Copaxone, which pulled in $4.3 billion in sales last year, but the FDA pushed back, requesting that Teva resubmit its proposal as a citizen’s petition so that others could weigh in.

In addition to the citizen’s petition, Teva has also mounted legal challenges to Copaxone generics that have gone as far as the U.S. Supreme Court. In April, Chief Justice John Roberts denied Teva’s request to put aside a lower court ruling invalidating one of Copaxone’s patents as too ambiguous. The Supreme Court is scheduled to hear full arguments on Copaxone’s ‘808 patent sometime next year.

Meanwhile, Teva also has been trying to give new life to its Copaxone exclusivity by switching patients from the 20mg version covered under the ‘808 patent to a 40mg dose.

Another legal challenge filed to protect Copaxone targeted the FDA itself: a lawsuit seeking to force the agency to require ANDA filers to meet additional requirements. That lawsuit was tossed by a federal judge in May. — Bryan Koenig

Originally appeared in Drug Industry Daily, the pharmaceutical industry’s number one source for regulatory news and information. Click here for more information.