The notice begins by stating that “it is well established that methods of medical treatment and surgery are not statutory subject matter and are excluded from the definition of invention.” This is fair summary of the law. In my view the SCC decision in Tennessee Eastman v Commissioner of Patents, [1974] SCR 111, which is usually cited on this point, really turned on s 41, which is now repealed, but the Federal Courts have consistently read it more broadly, and the point is now established in the Federal Court jurisprudence, independently of the authority of Tennessee Eastman.
The Notice then states that “Medical use claims, however, are generally permitted as long as they do not equate to medical or surgical methods . . . The Federal Court has concluded, however, that inventions preventing physicians from exercising their skill and judgment in using a known compound for an established purpose effectively cover a method of medical treatment.” This is also a fair summary of the case law.
However, the Notice then goes on to say:
[If] it is determined after a purposive construction that a dosage regimen or dosage range
is an essential element of a claim encompassing the use of a known compound in an
established treatment, then the claim covers a method of medical treatment, and thus, is
not compliant with section 2 of the Patent Act.
Where an essential element only serves to instruct a medical professional “how” to treat a
patient, rather than “what” to use to treat the patient, this will lead to the conclusion that
the claimed use encompasses a method of medical treatment.
The apparently blanket rejection of dosage regime claims is not consistent with the case law.
In Merck v Apotex / alendronate 2005 FC 755, 41 CPR(4th) 35, concerning 2,294,595, the inventive concept was the discovery that a single large weekly dose had fewer side effects than an equal amount taken on a daily basis [27], and the patentee claimed the composition in the specified dosage and dosing interval, as well the composition “for use” in the specified dosage and dosing interval [28]. Mosley J held that these claims were not an unpatentable method of medical treatment, though his reasoning was very cursory as he had held the patent invalid for obviousness [133]-[138]. In contrast, in Axcan v Pharmascience / URSODIOL 2006 FC 527, 50 CPR(4th) 321 concerning 1,318,590, Harrington J. in the Federal Court held that a claim to a dosage form of a pharmaceutical composition for treatment of cirrhosis was an unpatentable on the sole basis that it was a method of medical treatment. Harrington J described the holding of Mosley J in alendronate, but he did not attempt to distinguish it.
In finasteride Hughes J reviewed these cases and reconciled them by saying that "In Axcan, Harrington J. found the claim to be invalid because it was directed to a dosage range in which it was left to the physician to make on appropriate selection" [112]. At the same time Hughes J approved Mosley J's alendronate decision [112]. This is significant, because, as noted, subject matter was only a secondary consideration in Mosley J's decision, so it is relatively weak authority on its own. Consequently, Hughes J concluded that [114]:
a distinction must be made between claims that rely upon the skill and judgment of a
medial practitioner and those that deal with a vendible product, be it a scalpel, X-ray
machine or 1 mg tablet that are to be used or prescribed for use by such practitioner.
Thus in Hughes J’s view, it is not any dosage regime which is unpatentable, but only a dosage regime which requires skill and judgment.
This is reinforced by his holding on the facts that the claim in question was not unpatentable as being a method of medical treatment. In finasteride only Claim 5 of Patent 2,173,457 was at issue. After incorporation of prior references [5], Claim 5 reads:
5. The use of [finasteride] for the preparation of a medicament adapted for oral
administration useful for the treatment of male pattern baldness in a person and wherein
the dosage amount is about 1.0 mg.
Hughes J expressly construed this claim such that “having a dosage at about 1.0 mg” was an essential element [101]. Nonetheless, he held it was patentable subject matter: "In the present case, we have a 1.0 mg tablet taken as a daily dose. No skill or judgment is brought to bear. It is a vendible product and not a method of medical treatment" [114].
The Practice Notice cited Hughes J’s finasteride decision, but only in an introductory sentence saying that the Notice was intended to reflect judicial decisions. Despite that intent, I do not see how the statement that a claim is an unpatentable method of medical treatment if “a dosage regimen or dosage range is an essential element of a claim,” can be reconciled with finasteride. And apart from fine points of doctrine, there are now two cases holding dosage regime claims are patentable subject matter, and one to the contrary.
