are in common use, however, are themselves acidic, which would ordinarily cause the drug to deteriorate while
in storage, but the storage stability of the drug is enhanced if it is mixed with an alkaline compound. It was
found that when such an alkaline core is enteric coated some diffusion of moisture through the coating occurs
during the time that the dosage resides in the stomach, which dissolves part of the core in the proximity of the
coating with the result that an alkaline solution forms under the enteric coating and dissolves it from within.
That problem is overcome, according to the invention, by coating the alkaline core with a substance that forms
a barrier between the alkaline core and the outer enteric coating. It is the composition of that subcoating layer
that lies at the centre of the present dispute.
[5]
The invention is claimed as follows in claim 1 of the patent specification (some of the remaining claims are of
secondary relevance to this appeal and I will return to them later in this judgment):
"1. An oral, pharmaceutical preparation in the form of enteric coated tablets or pellets, containing omeprazole as
the active ingredient characterized in that it is composed of:
(a) alkaline core material containing omeprazole together with an alkaline reacting compound, or an alkaline
salt of omeprazole optionally together with an alkaline reacting compound, and
(b) on said alkaline core material one or more inert reacting subcoating layers comprising tablet excipients
which are soluble or rapidly disintegrating in water, or polymeric, water soluble, filmforming compounds,
optionally containing pHbuffering, alkaline compounds between the alkaline core material and
View Parallel Citation
(c) an outer layer, which is an enteric coating."
[6]
The dispute falls within a narrow compass. Paragraph (b) of claim 1 envisages the active alkaline core of
paragraph (a) being subcoated with one or more layers "comprising tablet excipients which are soluble or
rapidly disintegrating in water, or polymeric, water soluble, filmforming compounds". The active alkaline core of
respondent's product, Ulzec, is subcoated with a single compound (polyvinyl pyrrolidone, which is a water
soluble, filmforming polymer). The respondent alleges that it is an essential element of the claim that the
subcoating layer or layers should be constituted of more than one excipient or compound and that because the
alkaline core of Ulzec is subcoated with a single compound the patent is not infringed.
[7]
In Letraset Ltd v Helios Ltd 1972 (3) SA 245 (A) at 274GH Van Winsen JA, writing for the court on that issue,
described the nature of the enquiry into infringement as follows:
"The determination of the question as to whether or not plaintiff has proved an infringement of his patent turns
upon a comparison between the article or
Page 142 of [2002] 4 All SA 138 (SCA)
process, or both, involved in the alleged infringement and the words of the claims in the patent. If the article or
process falls within the ambit of the claims, properly construed: an infringement is proved. But the article or
process will not be regarded as falling outside the scope of the claims if such differences as the comparison may
disclose are not matters of any substance. In making the comparison the law looks at the essence of what is
contained in the claim and will not allow what is described as the "pith and marrow" of the protected invention to
be pirated. The evaluation of what is the substance or essence of an invention is a matter for the "good sense" of
the judicial tribunal seized with the enquiry."
[8]
While the enquiry into infringement requires the allegedly infringing article or process to be compared against
the language of the claim, it appears from that dictum, and has subsequently been repeated by this Court, that
the language of the claim must be construed purposively, so as to extract from it the essence, or the essential
elements, of the invention (Multotec Manufacturing (Pty) Ltd v Screenex Wire Weaving Manufacturers (Pty) Ltd
1983 (1) SA 709 (A) at 722AD; Stauffer Chemical Co and another v Safsan Marketing and Distribution Co (Pty) Ltd
and others 1987 (2) SA 331 (A) at 343A344D; Sappi Fine Papers (Pty) Ltd v ICI Canada Inc (Formerly CIL Inc)
1992 (3) SA 306 (A) at 319I). For as pointed out by Lord Diplock in Catnic Components Limited and another v Hill
and Smith Limited [1982] RPC 183 (HL) at 242, in a passage that was approved and adopted by this Court in
the cases I have referred to:
". . . a patent specification is a unilateral statement by the patentee, in words of his own choosing, addressed to
those likely to have a practical interest in the subject matter of his invention (ie "skilled in the art"), by which he
informs them what he claims to be the essential features of the new product or process for which the letters patent
grant him a monopoly. It is those novel features only that he claims to be essential that constitute the socalled
"pith and marrow" of the claim. A patent specification should be given a purposive construction rather than a
purely literal one derived from applying to it the kind of meticulous verbal analysis in which lawyers are too often
tempted by their training to indulge. The question in each case is: whether persons with practical knowledge and
experience
View Parallel Citation
of the kind of work in which the invention was intended to be used, would understand that strict compliance with a
particular descriptive word or phrase appearing in a claim was intended by the patentee to be an essential
requirement of the invention so that any variant would fall outside the monopoly claimed, even though it could
have no material effect upon the way the invention worked."
[9]
In Multotec Manufacturing (supra) at 721CE Corbett JA observed that a court should always guard against "too
'textual' an approach" in the interpretation of claims in a patent specification because by "peering too closely at
the language of a claim the Court may overlook an infringement that takes the substance of the invention."
While the claim must be construed to ascertain the intention of the inventor as conveyed by the language he