Global Insight Perspective | |
Significance | A U.S. appeals court reversed a lower court ruling upholding Pfizer's U.S. patent covering amlodipine besylate; the active ingredient in Norvasc. |
Implications | Norvasc is Pfizer's second-highest selling drug and its earlier-than-expected patent protection loss could cost Pfizer as much as US$1 billion in lost revenues this year. |
Outlook | The court decision is in favour of Apotex, but the benefits of Norvasc's early patent protection loss would be reaped by another generics challenger—U.S. company Mylan. As the first-to-file for approval of generic amlodipine with Paragraph IV certification, Mylan will be entitled to 180 days of marketing exclusivity in the United States. Pfizer said it "is considering all its options" and could yet launch another legal bid to protect Norvasc. |
Norvasc Patent Loss Comes Surprisingly Early
Last month, Mylan lost its bid to invalidate the key patent protecting Norvasc (U.S. Patent no. 4,879,303) when the U.S. District Court for the Western District of Pennsylvania decided to uphold the latter. Mylan's inability to overturn the '303 patent came hot on the heels of similar court losses for other generics drug-makers, including Apotex and Synthon (U.S.). Apotex decided to appeal, and in a surprise ruling the Court of Appeals of the Federal Circuit has now granted it.
The appeals court decision reverses the ruling of a lower court, the U.S. District Court for the Northern District of Illinois, which had upheld the validity of Pfizer's '303 patent for Norvasc. In its ruling, the appeals court said the lower court had ”erred” when it disagreed with Apotex and found that Pfizer's discovery process for the patent was unique, according to a Reuters report. As a result of the ruling, Pfizer's '303 patent—the key patent protecting the active ingredient of Norvasc—is currently invalid. The market is wide open for generic copies of Norvasc unless Pfizer launches an appeal against the latest court ruling and obtains an injunction, preventing generics from being launched until the patent protection case is resolved.
Mylan to Benefit from Case Outcome
The ruling is in favour of Canada's Apotex and came in response to the latter's legal appeal. However, the winner is likely to be Mylan. The U.S. generics company is believed to be the first to file for approval of a generic copy of Norvasc and its filing contained the so called Paragraph IV certification (essentially claiming that the patent protecting the branded drug is invalid). If generics are allowed to be launched early because the patent is invalidated, the first-to-filer with Paragraph IV is allowed to enjoy 180 days marketing exclusivity in the United States. The privilage in this case falls to Mylan, which is largely expected to launch its copy of amlodipine in the United States as early as next week.
Mylan filed its original abbreviated new drug application (ANDA) in May 2002 for 2.5 mg, 5 mg and 10 mg of amlodipine.
Outlook and Implications
Pfizer's '303 patent protects the besylate salt of amlodipine (which was switched from maleate salt due to better chemical stability in the original new drug application—NDA—in 1987). Its Norvas patent was originally due to expire this month, but Pfizer managed to extend patent protection by six months (to September 2007) after obtaining paediatric approval for Norvasc.
The invalidation of the patent comes six months earlier than expected. Although the patent loss has been factored in for the company's 2007 performance, considering the size of Norvasc sales, the impact on revenue will be substantial. Nine months of generic competition in the United States (as opposed to three if generics were prevented from entering the market until September) would cost Pfizer at least US$1 billion in lost revenues based on the company's 2006 Norvasc sales of US$2.5 billion. In absolute terms, the US$1 billion would have little impact on Pfizer and yet the sum is substantial enough to make Pfizer consider its strategic options seriously. The company may appeal and seek an injunction to block generic copies of Norvasc from entering the market until the patent protection case is resolved. Alternatively—and this is the more likely scenario, from Global Insight's perspective—Pfizer could launch an authorised generic of Norvasc in a bid to boost revenues and stem its losses from generic competition. Ironically, Apotex may emerge as a suitable partner for an authorised generic, considering the latter won the appeal but may not reap the benefits until Mylan's exclusivity expires.