Issue 180 | April 5, 2004
Pfizer Inc. v. Dr. Reddy's Labs, Ltd.


35 U.S.C. 156(b) – A patent term extension, granted to compensate the patent owner for the regulatory delay required to obtain FDA approval for one salt of a new drug, also extended the term of the patent respecting another salt of the same drug, which was covered by the claims but not FDA approved for marketing.

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The Federal Circuit reversed the judgment below that defendant Reddy does not infringe the extended term of the '909 patent. The Federal Circuit concluded that the extended patent term includes the claims that cover Reddy's product.

The Pfizer '909 patent claims the drug amlodipine and its acid addition salts.

Pfizer obtained FDA registration of a drug product whose active ingredient was the besylate salt of amlodipine. Pfizer submitted clinical data obtained using both the besylate salt and the maleate salt of amlodipine. The besylate salt was selected by Pfizer for ease of tableting.

The seventeen-year term of the '909 patent ended on February 25, 2003, but the patent term was extended until July 31, 2006, under the Federal statutory scheme to compensate the patent owners for the portion of the patent term lost to the FDA approval process during the term of the patent. A drug cannot be marketed without FDA approval, even though it is patented.

In Pfizer's application to the United States Patent and Trademark Office (PTO) requesting patent term extension under 35 U.S.C. Section 156, Pfizer identified amlodipine besylate as the product for which regulatory approval had been obtained.

In December 2001 Reddy filed a new drug application proposing to market the maleate salt of amlodipine. Reddy acknowledged that amlodipine maleate is covered by the claims of the '909 patent, but argued that the term extension applies only to the besylate salt because that is the FDA-registered product. The district court agreed with Reddy.

Reddy argued that only the specific salt for which Pfizer obtained approval is protected by the extended term of the patent. In particular, Reddy argued that the district court properly held that Section 156(b) limits the rights derived under the extended term of a patent to the specific form of the approved product, i.e., a free base or a specific salt.

35 U.S.C. Section 156(f) defines the term "drug product" as the active ingredient of a new drug, including any salt or ester of the active ingredient, as a single entity or in combination with another active ingredient.

The Federal Circuit concluded that the active ingredient is amlodipine, and that it is the same whether administered as the besylate salt or the maleate salt. The statute foresaw variation in the salt or ester of an active ingredient, and guarded against the very loophole now urged. None of the aspects offered to the district court or on this appeal suggested a statutory intent to provide the generic producer with access to the pioneer's approved uses and data while barring extension of patent coverage of the drug product whose approvals and data are provided.

Judge Mayer dissented. He believed the district court correctly interpreted 35 U.S.C. 156(b) to limit the patent term to the specific product that was the subject of Food and Drug Administration approval. Regardless of how a product is defined in section 156(f), to be eligible for a patent term extension, that product must have been subject to a regulatory review period before its commercial marketing or use. In this case, the product subject to regulatory review was amlodipine besylate. It was not merely amlodipine, nor was it amlodipine maleate, the product that Reddy seeks approval to market. As such, the product amlodipine maleate cannot qualify for a patent term extension; it does not comport with the statutory requirements for eligibility.

Please e-mail George Wheeler of McAndrews, Held & Malloy, Ltd. at gwheeler@mhmlaw.com with any questions that you might have about this case.

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