Pfizer has teamed up with Dutch firm Synthon to produce a generic of Teva’s blockbuster multiple sclerosis drug Copaxone.

Synthon’s version of the drug, glatiramer acetate, is already under review by the FDA in the US. Under the terms of the agreement, Pfizer will have exclusive rights to commercialise the drug in the country. Synthon is responsible for the clinical development, manufacture and supply of glatiramer acetate. Financial terms of the deal were not disclosed.

It will not be the first Copaxone generic to hit the market, though – Novartis and Momenta’s Glatopa already launched earlier this year. Mylan and Natco Pharma have also developed their own version.

However, as Synthon’s version was filed first in 2011, the company says that it may be eligible for six months of market exclusivity in the US under the Hatch-Waxman Act.

Copaxone generated more than $4 billion in sales for Teva in the first half of the year. Its patents were originally due to expire in September, but the US Court of Appeals invalidated its protection in June.

Teva is hoping to switch as many patients as possible to a longer-acting, 40mg formulation of the drug. However, Synthon’s version is also under review for this dosage.