Legal decision could delay biogenerics in US
generic version of Pfizer's blockbuster hypertension drug Norvasc
(amlodipine besylate) in a development that could spell trouble for
companies hoping to market generic versions of biologic drugs.
The US Court of Appeal for the Federal Circuit in Washington ruled on Friday that Dr Reddy's AmVaz (amlodipine maleate) contravened Pfizer's patents on Norvasc, guarding the product from competition for some time, and perhaps as long as 2007. The court overturned an earlier decision in Dr Reddy's favour.
This is a significant victory for Pfizer - Norvasc is one of its top products with sales of $4.34 billion (€3.48bn) last year, and $1.93 billion of that total coming from the US market.
Dr Reddy's had tried to win approval for AmVaz by taking the product down a little-used regulatory route known as a 505(b)(2) filing. In the US, the approval of generic versions of marketed drugs that are not exactly identical to the original product are allowed via this route by allowing a sponsor to reference the safety data from an existing New Drug Application (NDA).
Dr Reddy's had filed for a different salt of the hypertension drug, AmVaz (amlodipine maleate) on this basis. But Pfizer argued that its patents on Norvasc should cover any salt of amlodipine, and the upper court agreed.
While the implications of the case for Dr Reddy's are significant - the company has not had a major product launch for a couple of years and is embroiled in legal challenges with Eli Lilly over a generic version of its Zyprexa (olanzapine) for schizophrenia - it could also affect the embryonic biogenerics industry.
Generic biologicals (such as human growth hormone and insulin), which are expected to be evaluated under a 505(b)(2) filing in the US, could see their path to approval blocked by the precedent set in the Pfizer/Dr Reddy's ruling.
Pfizer had argued in its appeal that Dr Reddy's had contravened its patents because it had relied on safety data generated with Norvasc in its application for AmVaz.
Originator companies could use the precedent set by the Pfizer case to fight off biogenerics by forcing their sponsors to generate proprietary safety data for their products, raising the financial bar for generic biologicals and delaying approval.
Because biologics are approved on the basis of purity, potency and identity, rather than safety and efficacy as is the case with conventional drugs, current law requires that a biologic must always be produced using an identical manufacturing process.
This is near-impossible for biogenerics companies to achieve, so without recourse to cited data using 505(b)(2), they could down the route of carrying out a full, expensive clinical development programme for their biogeneric.
