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King Pharmaceuticals, Inc. v. Eon Labs

January 20, 2009


The opinion of the court was delivered by: David G. Trager United States District Judge



Plaintiffs King Pharmaceuticals, Inc. and King Pharmaceuticals Research and Development, Inc. (collectively, "King") brought this action against defendant Eon Labs, Inc. ("Eon") for infringement of U.S. Patents Nos. 6,407,128 ("the '128 patent") and 6,683,102 ("the '102 patent"), which are directed to methods of informing patients about and administering the muscle relaxant metaxalone - marketed by King under the brand name "Skelaxin(r)" - with food.

Eon now moves for summary judgment of invalidity of the '128 and '102 patents, and King moves to dismiss Eon's counterclaims.

Background*fn1 The Food and Drug Administration ("FDA") first approved use of metaxalone in the early 1960s. The patent on metaxalone was issued in 1962 and expired long ago. See U.S. Patent No. 3,062,827. King's predecessor, Elan Pharmaceuticals, Inc. ("Elan") had been marketing Skelaxin in a 400 mg strength tablet for some time when it sought approval to market Skelaxin in an 800 mg strength tablet. In response, the FDA required Elan to conduct a bioequivalence study. Elan protested the requirement, writing to the FDA to explain the reasons it did not believe a bioequivalence study was necessary. Despite its initial reluctance, Elan ultimately did conduct a bioequivalence study. In the course of the study, Elan discovered that the drug is found in greater concentrations in the blood of fed subjects than in the blood of fasting subjects. Armed with these test results, Elan filed a patent application with the United States Patent and Trademark Office, claiming a method of increasing the bioavailability of metaxalone by administering it with food. This application eventually issued as the '128 patent. After purchasing certain patent rights from Elan, King filed a continuation patent application which issued as the '102 patent.


(1) Validity

Eon alleges that all of the claims of the '128 and '102 patents are invalid for anticipation by the prior art under 35 U.S.C. § 102(b), and that a subset of the claims are alternatively invalid for obviousness under 35 U.S.C. § 103(a). The patents are presumed valid, and Eon has the burden of proving invalidity by clear and convincing evidence. Bristol-Myers Squibb Co. v. Ben Venue Labs., Inc., 246 F.3d 1368, 1374 (Fed. Cir. 2001).

A patent is invalid if the invention claimed in it was "described in a printed publication in this or a foreign country . . . more than one year prior to the date of the application for patent in the United States." 35 U.S.C. § 102(b). For a prior art publication to "anticipate" a patent claim, it must "expressly or inherently disclose each claim limitation." Finisar Corp. v. DirecTV Group, Inc., 523 F.3d 1323, 1334 (Fed. Cir. 2008). On the other hand, a claim is invalid for obviousness when "the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains." 35 U.S.C. § 103.

a. The Prior Art

Eon points to six prior art references that it argues invalidate the claims of the '128 and '102 patents under either 35 U.S.C. § 102(b) or § 103.

i. Fathie I

In November 1964, Kazem Fathie, M.D., published an article titled, "A Second Look at a Skeletal Muscle Relaxant: A Double-Blind Study of Metaxalone," in 6 Current Therapeutic Research 677 ("Fathie I"). Decl. of Mher Hartoonian in Supp. of Def. Eon Labs, Inc.'s Mot. for Summ. J. that the '128 and '102 Patents Are Invalid for Anticipation and/or Obviousness ("Hartoonian Decl."), Ex. 3. Fathie I describes two double-blind studies in which patients with "low-back pain and discomfort" were administered either metaxalone or placebo. Those who received metaxalone were prescribed a recommended dose of "two [400 mg] tablets after each meal and at bedtime." Id. at 678-79 (emphasis added).

ii. Fathie II

In April 1965, Dr. Fathie published an article titled, "Musculoskeletal Disorders and Their Management with a New Relaxant," Clinical Medicine 678 ("Fathie II"). Hartoonian Decl., Ex. 4. In it, Dr. Fathie describes a clinical study in which metaxalone was administered to patients with musculoskeletal disorders. The patients were prescribed 800 mg of metaxalone, to be taken three or four times daily. The article notes that "[metaxalone was well accepted and except for mild nausea in six cases, was apparently well tolerated. Nausea might have been less prominent if the medication had been taken with food." Id. at 682 (emphasis added).

iii. Morey

Lloyd W. Morey and Allan R. Crosby published an article entitled, "Metaxalone, a new skeletal muscle relaxant," in The Journal of the American Osteopathic Association 517/61 in February 1963. Hartoonian Decl., Ex. 5. In it, they describe a study in which 61 patients suffering from striated muscular spasm were "given two tablets four times daily, after meals and at bedtime; the amount of the metaxalone per capsule was 400 mg., for those who received it." Id. at 518/62 (emphasis added).

iv. Albanese

Joseph A. Albanese published an entry on metaxalone in the 1982 edition of Nurses' Drug Reference (2d ed.). Hartoonian Decl., Ex. 6. Albanese teaches that metaxalone is available in 400 mg tablets, that the dose range for metaxalone is "800 mg 3-4 times daily" and also that "[a]dministration with meals will help reduce gastric upset." Id. at 427 (emphasis added).

v. Abrams

In 1995, Anne C. Abrams published Clinical Drug Therapy (4th ed.), in which she teaches that metaxalone should be administered in a dosage of "800 mg 3 or 4 times daily" and that it should be given "with milk or food [to] decrease gasrointestinal distress." Hartoonian Decl., Ex. 7 at 146-47 (emphasis added).

vi. Dent

In September 1975, R.W. Dent, Jr. and Dorothy K. Ervin published an article entitled, "A Study of Metaxalone (Skelaxin) v. Placebo in Acute Musculoskeletal Disorders: A Cooperative Study," in Current Therapeutic Research, vol. 18, no. 3. Hartoonian Decl., Ex. 13. They describe a study in which "[p]atients were given either metaxalone 400 mg or placebo in tablets of identical appearance. The starting and most common dosage was two tablets four times daily.... However, the only other acceptable schedule was one tablet q.i.d. [four times daily]." Id. at 434 (emphasis added).

Thus, Fathie II, Albanese and Abrams all describe or suggest taking metaxalone with food; Fathie I and Morey both disclose taking metaxalone after meals; and Dent describes taking metaxalone four times daily. King admits that each of these publications list publication dates that predate the applications for the '128 and '102 patents by more than one year, yet it denies that they qualify as prior art under 35 U.S.C. § 102(b).*fn2

The basis for King's denials is unclear, given that "[p]rinted materials purporting to be newspapers or periodicals" are self-authenticating under Fed. R. Evid. 902(6).

b. The Patents in Suit

i. The '128 patent

The '128 patent contains twenty-two claims, three of which are independent. Each of the independent claims (claims 1, 9 and 17) requires the steps of administering metaxalone to a patient with food.

Claim 1

Specifically, claim 1 of the '128 patent requires:

1. A method of increasing the oral bioavailability of metaxalone to a patient receiving metaxalone therapy comprising administering to the patient a therapeutically effective amount of ...

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