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denied that is not the invention covered by claim 1. Although directly contradictory, each party found support
for its interpretation in the body of the patent specification, which reads in relevant part, under the heading
"Detailed disclosure of the invention:"
"Drospirenone . . . is a sparingly soluble substance in water and aqueous buffers at various pH values. Furthermore,
drospirenone is rearranged to an inactive isomer under acid conditions and hydrolysed under alkaline conditions. To
ensure good bioavailability of the compound, it is therefore advantageously provided in a form that promotes rapid
dissolution thereof.
It has surprisingly been found that when drospirenone is provided in micronised form . . . rapid dissolution of the
active compound from the composition occurs in vitro ('rapid dissolution' is defined as the dissolution of at least 70%
over about 30 minutes . . . of drospirenone from a tablet preparation containing 3 mg of drospirenone in 900 ml of
water at 37ºC determined by the USP XXIII Paddle Method using a USP dissolution test apparatus 2 at 50 rpm).
Instead of providing the drospirenone in micronised form, it is possible to dissolve it in a suitable solvent, e.g.
methanol or ethyl acetate, and spray it onto the surface of inert carrier particles followed by incorporation of the
particles containing drospirenone on their surface in the composition.
Without wishing to be limited to any particular theory, it appears that the in vitro dissolution rate of drospirenone is
connected to the dissolution rate in vivo resulting in rapid absorption of drospirenone in vivo on oral administration of
the compound. This is an advantage because isomerisation of the compound in the gastric environment and/or
hydrolysis in the intestine is substantially reduced, leading to a high bioavailability of the compound. . . .
The composition of the invention may be formulated in any manner known in the pharmaceutical art. In particular, as
indicated above, the composition may be formulated by a method comprising providing drospirenone and, if desired,
ethinylestradiol in micronised form in said unit dosage form, or sprayed from a solution onto particles of an inert
carrier in admixture with one or more pharmaceutically acceptable excipients that promote dissolution of the
drospirenone and ethinylestradiol so as to promote rapid dissolution . . . on oral administration."
[30] On Pharma's construction of these paragraphs the "surprising finds" made were, that when DSP is provided in
micronised form (or dissolved and sprayed onto the surface of the particles of an inert carrier), rapid
dissolution of the active compound from the composition in vitro is achieved. With regard to the contrary
interpretation contended for by Bayer ie that it covers the invention described by Prof Davies Pharma
pointed out that there is no indication that the "surprising finds" relate to rapidly dissolving DSP leading to
good bioavailability in vivo without the need for it to be protected by an enteric coating. In fact, so Pharma
argued, the specification does not even refer to the subject of enteric coatings at all. Its only topic of
discussion is the rapid dissolution of DSP and the two methods in which this can be attained.
[31] I do not believe, however, that this is how the skilled addressee would understand the specifications. First of
all, the fact that rapid dissolution could be achieved in vitro through one of the two methods referred to, was
wellknown at the time. Indeed, it was common knowledge amongst those skilled in the art that the same
result could be achieved in at least five ways. Hence, rapid dissolution by these two methods could never
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have been understood by those skilled in the art to constitute the "surprising finds". What the "detailed
disclosure" teaches at the outset, as I said, is that DSP is (a) sparingly soluble in water and at the same time,
(b) unstable in an acidic environment, in that it rearranges into an inactive isomer in these conditions (ie that
DSP is acid labile). It then continues to explain that despite (b) it has surprisingly been found that when
DSP is provided in a rapidly dissolving form (which would ordinarily mean that both the solubility and the risk
of degradation as a result of acid lability, were increased) high bioavailability was nonetheless attained in
vivo. To the skilled operator, the "surprising find" described would therefore be, in my view, the invention
described by Prof Davies, which indeed came as a surprise to Bayer's development team. It is true that all this
is not explicitly stated in the specification and that no mention is made, for instance, of enteric coatings. But
as appears from the authorities I have referred to at the outset, one must read the specification through the
eyes of a person skilled in the field and avoid the undue focus on a literal analysis in which lawyers tend to
indulge.
[32] As I read it, there is therefore no basis upon which the limitation proposed by Pharma can conceivably be read
into the claim of the patent in the context of the specification. On the contrary, I think the plain meaning of the
claim read with the specification goes the other way. First of all it teaches that DSP can be provided in
micronised form or "instead" that "it is possible" for the dissolution rate of integer E to be achieved through
the use of inert carrier particles. These are not statements from which one could infer that the claim should be
limited to a particular method of achieving a dissolution rate. But what settles the matter, I think, is the
patentee's express statement that "composition of the invention may be formulated in any manner known in
the pharmaceutical art". This means that the composition of the invention could be formulated in any known
manner that would achieve the dissolution rate specified in integer E, which includes the method employed in
the formulation of Pharma's Ruby product.
[33] In sum, I therefore agree with the court a quo's finding that the skilled reader of the patent (reading it as a
whole) would accept that claim 1 covers any method of achieving the dissolution rate of integer E; that
Pharma's Ruby product therefore falls within the compass of the claim and consequently infringes the 2004
patent.
Inventive step
[34] This brings me to Pharma's attack against the patent on the basis that it lacked an inventive step. The
challenge must of course be understood in the light of section 25(10) of the Act which requires that, in order