Buprenorphine - UK

On Nov 01, 2016, Court of appeal (UK) handed down its decision in Napp Pharmaceutical Holdings Limited v (1) Dr Reddy's Laboratories (UK) Limited (2) Sandoz Limited [2016] EWCA Civ 1053 case regarding Buprenorphine transdermal product.

The appeal was filed by Napp pharma against judgment dated 28 June 2016 ([2016] EWHC 1517 (Pat)), by Arnold J in favor of DRL and Sandoz finding non-infringement. The court of appeal finally dismissed the appeal.

The case concerns EP 2 305 194 patent in respect of buprenorphine, formulated as a transdermal patch for use in the treatment of chronic pain.  Napp contended that both Dr Reddy's and Sandoz threatened to infringe the patent by marketing their own transdermal patches.

The appeal concerned the construction of claim 1 which reads as follows:

"A buprenorphine transdermal delivery device comprising a polymer matrix layer containing buprenorphine or a pharmaceutically acceptable salt thereof, for use in treating pain in humans for a dosing interval of at least 7 days, wherein the transdermal delivery device comprises 10%-wt buprenorphine base, 10 to 15%-wt levulinic acid, about 10 %-wt oleyloleate, 55 to 70%-wt polyacrylate, and 0 to 10%-wt polyvinylpyrrolidone."

Issue was the correct interpretation of the numerical features of the claim, and in particular, what is meant by "10%-wt buprenorphine base", "10-15%-wt levulinic acid" and "about 10%-wt oleyloleate".  At first instance, Arnold J considered that buprenorphine and levulinic acid were expressed to the nearest whole number (and therefore covered 9.5-10.5%-wt for buprenorphine, and 9.5-15.5%-wt for levulinic acid).  As to "about 10%-wt oleyloleate", Arnold J held that this allowed a margin of error of 1% around the figure of 10%-wt, because the word "about" would be understood to give a small degree of imprecision over and above that permitted by normal rounding.

The Court of Appeal reiterated the approach to construction of numerical features and ranges in patent claims as set out in paragraph 38 of Smith & Nephew plc v ConvaTec Technologies Inc [2015] EWCA Civ 607. Napp submitted that the patentee had chosen to express himself to the nearest 5% for at least buprenorphine and levulinic acid in claim 1, and noted that the patent worked in increments of 5%.  The Court of Appeal recognised that the figures in the patent were indeed in multiples of 5%, but that did not tell one anything about the degree of precision to which these numbers are expressed.  If the patentee had wished to claim, for example, 7.5-12.5%-wt buprenorphine he could have done so by making express provision in the claim.  The figures were expressed to the nearest whole number.