ROBINS' MICRO-K EXTENCAPS DOSAGE PATENT HELD INVALID

ROBINS' MICRO-K EXTENCAPS DOSAGE PATENT HELD INVALID on grounds of "obviousness," Columbus, Ohio Federal Court Judge James Graham determined on April 18. Graham's ruling invalidates the patent for the extended release/microencapsulation mechanism used in the company's top-selling potassium chloride product. American Home Products' A. H. Robins filed a patent infringement suit against Erbamont subsidiary Adria Labs in October 1989. Robins charged that Adria Labs' K-Lease potassium chloride capsules with myristic acid-treated shell walls infringed the company's patent for a "Controlled-Release Potassium Dosage Form." However, Graham ruled that Robins' patent was invalid because it involved technology "which is taught or obvious in view of prior art." In his decision against Robins, Graham noted that the basic chemical processes involved in the Micro-K dosage form -- the use of microencapsulation techniques and surfactants to control the dispersibility patterns of drug substances -- were "well known in the pharmaceutical art and had been known since the 1960s." Graham wrote that even if the court were to consider the Micro-K patent valid, Robins would still be unable to claim patent infringment because of differences in the two products' chemical formulations and modes of action. "Myristic acid in the shell wall of the Adria microcapsules does not perform the same function in the same way to obtain the same result as the hydrophilic surfactant external to the microcapsules described in the [Micro-K] patent," the decision states. Still pending in the dispute is a 1989 counterclaim filed by Adria parent Erbamont alleging that Robins "brought their suit in a bad faith attempt to exclude competitors from the market." Adria received an ANDA for K-Lease on April 1990 and has been marketing their version of the extended-release potassium chloride since June. If the court's rule in favor of Erbamont on the counterclaim, the company will receive financial damages. Robins has not yet announced whether they intend to appeal Judge Graham's decision.