BuSpar: Will FDA list BMY new Buspar patent ?

December 4, 2000

Bristol Myers Squibb submitted  a new patent, (’365), (which it claims covers BuSpar), to the FDA for listing  in the Orange Book. The ’365 patent covers a “metabolite” of BuSpar  which is created in the body after Buspar is taken.  Normally, the FDA lists all patents in the Orange Book which are submitted  to it; but in an unusual move, the FDA  has decided to hold administrative hearings to determine if  ’365 should be listed. Meanwhile, the FDA has delayed issuing the final ANDAs for buspirone to Watson or Mylan.

Watson and Mylan have asked the two different federal courts to issue injunctions:

• 1- to block the listing of the new BuSpar patent (’365) in the Orange Book; and
• 2- to force the FDA to issue ANDAs on their generic drugs for buspirone.

Because the ’365 metabolite is only part of the chemical compound of BuSpar, there is a strong factual argument that ‘365 should not be listed with Buspar.  Moreover,  because the metabolite (’365) is chemically different from Buspar,  Bristol Myers has no valid claim for patent infringement that would justify the FDA’s delay in issuing the ANDAs to Watson and Mylan. .  Eventually, the FDA will issue the ANDAs to Watson and Mylan but either the administrative proceeding requested by the FDA or the federal courts must first decide that the metabolite is not BuSpar.

Although Verdict believes that the generic companies have a strong factual argument that the metabolite is chemically different than BuSpar, courts are reluctant to issue injunctions against the FDA. Watson and Mylan’s suits may  be designed to prod the FDA into “high gear.”  Although the final outcome will depend in part on strength of the arguments to be raised by the FDA and Bristol in their briefs, my hunch is that the Courts may  block the filing of the ’365 in the Orange Book, but may hesitate in ordering the issuance of the ANDAs.  Of course, once the Orange Book issue is decided, there would be no reason for the FDA not to issue the ANDAs.  Timing will depend on when the FDA and Bristol Myers file their briefs.