United States: Method of Treatment Interpreted to Include a Pharmaceutical Formulation of the Claimed Compound

In a case turning on claim construction, the U.S. Court of Appeals for the Federal Circuit affirmed a lower court’s ruling of infringement construing a claim directed to a treatment for bone reabsorption and urolithiasis to encompass the use of a pharmaceutical formulation of the active agent. Merck & Co., Inc. v. Teva Pharmaceuticals USA, Inc., Case No. 03-1168 (Fed. Cir. Oct. 30, 2003).
The drug Fosamax is marketed by Merck & Co. (Merck) and approved by the U.S. Food and Drug Administration (FDA) for the treatment of osteoporosis and Paget’s disease. The active agent of the product is formulated as a salt having the common name alendronate salt. The Merck patent in issue was U.S. Patent No. 4,621,077 (the `077 patent), which contained a single claim directed to a method of treating bone reabsorption and urolithiasis through the administration of the non-salt form of the compound, alendronic acid.

Alleging that the delivery of the acid as recited in the claimed method includes the delivery of the salt form, Merck sued the generic drug maker Teva Pharmaceuticals (Teva) for infringing the `077 patent claim when Teva filed for regulatory approval to sell the alendronate salt form. Teva defended its actions on the basis that the alendronate salt is distinct from the claimed acid form. The district court found that the method administering alendronic acid was infringed by the administration of alendronate salt.

In construing the claim, the Federal Circuit took notice that while extrinsic evidence cannot change the meaning of a term as it is used in the specification, expert opinion is not prohibited to explain the meaning of claim language used in the patent as it would be understood by those skilled in the field of the invention. Here, the Court framed the issue to be decided as whether a person skilled in pharmacology would understand from the specification that the claimed method of treatment by administering alendronic acid encompasses administering alendronate salt.

Affirming the lower court’s finding of infringement, the Federal Circuit found that the claimed acid form was exemplified in the specification in formulations that included the salt, and usage of the active agent in the salt form for the treatment of bone disorders was presented in the specification. The Court further found extensive evidence in the record that persons experienced in the field refer to the active ingredient in the form of the salt and that qualified witnesses in the field of pharmacology understood that the acid, which is administered in the form of the salt, is the active agent.