Novartis AG v Dexcel-Pharma Ltd

Patent claims must be construed from the perspective of the skilled person, having regard to the technical purpose of the claimed elements. A microemulsion pre-concentrate need not itself contain separate hydrophilic and lipophilic phases. It is sufficient that, on dilution in water during use, those components form the required phases in the resulting microemulsion.

The characteristics identified in a patent specification as indicating a microemulsion are not necessarily mandatory cumulative requirements. The question is one of overall judgment, including whether the dispersion performs the function of carrying the active ingredient. Borderline cases may involve fuzzy claim boundaries without rendering the claims incapable of infringement.

Novartis claimed infringement of United Kingdom Patent No 2 222 770, concerning pharmaceutical compositions comprising cyclosporin in the form of an oil-in-water microemulsion pre-concentrate or microemulsion. The patent’s validity had previously been upheld in Novartis AG v Ivax Pharmaceuticals UK Ltd [2006] EWHC 2506 (Pat).

Dexcel had not marketed Deximune in the United Kingdom. The issues were whether Deximune contained hydrophilic and lipophilic phases, whether it formed a microemulsion in the conditions of use, and whether that amounted to infringement of claims 1 and 48.

1. Construction. Applying the approach in Kirin Amgen Inc v Hoechst Marion Roussel Ltd [2004] UKHL 46, the claims were construed according to what the skilled pharmaceutical formulator would understand the language to mean, read in context and having regard to the technical purpose of the claimed elements.

2. The issue decided in Novartis AG v Ivax Pharmaceuticals UK Ltd [2007] EWCA Civ 971 was whether a lipophilic phase had to be distinct from the surfactant. It did not decide whether hydrophilic and lipophilic phases had to be separate in the pre-concentrate. The pre-concentrate need only be capable of forming the claimed microemulsion when adequate water is added. The required phase separation therefore had to exist in the resulting microemulsion, not necessarily in the pre-concentrate itself.

3. The word “microemulsion” was construed using the patent specification because the skilled person in 1988 had limited relevant knowledge. The listed characteristics were indicators rather than rigid cumulative conditions. The court had to make an overall judgment, taking account of the dispersion’s function of carrying the cyclosporin. The claims had fuzzy edges, but were sufficiently clear to be capable of infringement.

4. The relevant dilution was that occurring during administration. Deximune was expected to be diluted by at least approximately 1:10 and commonly around 1:20 or more. At those dilutions it was substantially non-opaque, formed substantially spontaneously, was sufficiently stable, monophasic and optically isotropic, and had particles predominantly below 2,000 Å. It therefore formed a microemulsion within the meaning of the patent.

5. Deximune contained a hydrophilic phase and a lipophilic phase and infringed claim 1. It also formed a microemulsion on administration and therefore infringed claim 48. Its marketing would infringe both claims.