Canadian group Biovail said yesterday it is taking the US Food and Drug Administration to court to try and prevent it from approving Anchen’s generic version of its antidepressant Wellbutrin XL, a sustained-release form of bupropion, before it addresses issues outlined in a Citizen’s Petition.

The Citizen’s Petition, which was filed last December, raised concerns over whether the copycat form of Wellbutrin has the same bioavailability as the branded product, and Biovail says it wants US regulators to resolve this query at least a week before it issues an approval for Anchen's copycat.

Earlier this month, a judge in a Toronto court ruled that although Biovail's patents on the sustained-release formulation of bupropion were valid, a copycat version developed by Anchen Pharmaceuticals did not infringe upon them.

Wellbutrin XL is a big source of revenue for Biovail. UK drug major GlaxoSmithKline licensed the compound in 2001 from the Candian group, which consequently gets an approximate 30% royalty rate on sales of the product, currently representing around 40% of its total turnover.

Shares in the group closed up 1% at $17.01 after the news.