Claritin Litigation Rehearing Denial Could Affect New Drug Patents

A Washington, D.C. federal appeals court ruling not to rehear Schering-Plough's adverse desloratadine patent infringement decision en banc could hold serious implications for future new drugs and biologics, two dissenting judges argue.

In an Oct. 28 decision, the court denied both of Schering's petitions for a panel rehearing and an en banc rehearing before the full court.

The request for a rehearing follows an Aug. 1 ruling by the D.C. appeals court that manufacturers of generic Claritin (loratadine) were not infringing on certain patent claims for Clarinex (desloratadine) (¹ (Also see "Generic Claritin Does Not Infringe Schering Patent - Appeals Court" - Pink Sheet, 4 Aug, 2003.), p.3).

Schering had appealed a New Jersey federal judge's ruling finding the patent claims invalid (² (Also see "Desloratadine Patent Claims No Bar To Generic Claritin, Judge Says" - Pink Sheet, 12 Aug, 2002.), p. 3).

Circuit Judge Pauline Newman, dissenting from the denials for rehearing, opined: "The panel's proposed rule may have particular impact on the discovery of biological products. Does the panel intend that no newly discovered product found in an organism can be patented? Such a ruling does not comport with either the patent statute or the incentive purposes of the patent system."

The court's decision not to rehear the case represents "an extraordinary decision, effectively precluding virtually all patents on human metabolites of drugs," according to dissenting Judge Alan Lourie.

However, in their decision the panel maintained that "with proper claiming," metabolites can be protected.

Newman asserts that "no precedent supports the position that a product whose existence was not previously known and is not in the prior art is always unpatentable on the ground that it existed undiscovered."

"The panel appears to have reached the correct result of no liability for infringement, but for the wrong reason," Newman notes. "However, instead of simply ruling that Schering cannot prevent the practice of the expired patent in accordance with its teachings, the panel strains to hold that this newly discovered, previously unknown product cannot be validly patented."

At issue is the court's finding that the claims relating to desloratadine were inherently anticipated by the practice of the loratadine patent, which results in the production of the metabolite when loratadine is ingested.

"That the thing was there, undiscovered, does not render it 'inherently anticipated,'" Newman argues. "In all applications of the law of anticipation, the initial consideration is whether the thing that is claimed was disclosed in a single prior art reference."

"When all of the elements of the claim are not shown in the prior art, precedent requires that the missing element was nonetheless known to be present in the subject matter of the reference, and that the claim is directed to the known subject matter."

However, Lourie points out the panel's decision holds "that an issued patent on a pharmaceutical product provides an enabling disclosure of all of that product's metabolites...simply by disclosing that the product can be used by administration to a human."

"Because product patents covering pharmaceutical products generally issue before clinical trials on the product have revealed the identity or nature of any metabolites, this decision will preclude protection of those metabolites as the issued patent will be effective prior art against such application."

The panel's decision mandates "that the mere issuance of the patent on the product - or any other publication of that product - inherently anticipated claims to the metabolite merely by disclosing that the product can be administered to a patient, on the theory that such administration would inevitably cause the human body to 'make' the metabolite," Lourie states.

This departure from precedent should be a matter for the full court, according to Newman. "If the law is to be changed in this direction, it must be done en banc. The court should speak with one voice on this important question." Schering's last legal recourse would be to take the case to the Supreme Court.

Separately, Schering announced it has reached a settlement with the last of the defendants regarding its Claritin-D formulation. The firm has agreed to license the patent relevant to Claritin-D 24 Hour Extended Release Tablets to Impax Labs for an undisclosed sum. The firm reached a similar agreement with generics firm Andrx for the D formulation.