The Food and Drug Administration (FDA) has expressed concerns about the therapeutic equivalence of two generic versions of Concerta (methylphenidate HCl extended-release; Janssen) tablets indicated for the treatment of attention deficit hyperactivity disorder (ADHD).

The two approved generics are manufactured by Mallinckrodt and Kudco Ireland. After analyzing adverse event reports, an internal FDA re-examination of previously submitted data, and FDA laboratory tests of Mallinckrodt and Kudco Ireland products, the FDA reported that the generic products may not produce the same therapeutic benefits for some patients as the brand Concerta.

Methylphenidate HCl Extended-Release products are designed to release the drug over a 10–12 hour period. However, the Mallinckrodt and Kudco products were shown to release the drug at a slower rate during the 7–12 hour range. A reduced release rate may lead to patients not achieving the desired therapeutic effect.

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The FDA has therefore changed the therapeutic equivalence rating from AB to BX for the Mallinckrodt and Kudco products. A BX rating implies that the products are still approved and can be prescribed, but are no longer recommended as automatic substitutes at the pharmacy for Concerta. Also, the FDA has modified its draft guidance for industry for bioequivalence testing for Methylphenidate HCl Extended-Release tablets.

Mallinckrodt and Kudco have been requested to confirm the bioequivalence of their products within six months, or voluntarily pull their products off the market.

Janssen also manufactures an authorized generic version of Concerta (marketed under Actavis). Its analysis showed it to be bioequivalent to, and substitutable for, brand Concerta. The FDA plans to further evaluate its testing and approval standards as well as its bioequivalence guidances for other generic Methylphenidate HCl Extended-Release products.

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