Alphapharm Pty Ltd v H Lundbeck A/S

In the matter of Alphapharm Pty Ltd v H Lundbeck A/S, the Federal Court of Australia considered the patentability of a pharmaceutical substance, specifically escitalopram, in relation to its parent compound, citalopram. The dispute centred on whether the substance escitalopram, which is a more potent enantiomer of citalopram, could be patented independently when citalopram itself was already patented. The patent in question related to the (+)-enantiomer of citalopram, known as escitalopram, marketed under the brand name Lexapro. The primary legal issue was whether escitalopram could be considered a distinct pharmaceutical substance for the purposes of patent law, separate from citalopram, and if it could be patented when citalopram was already registered and patented.

The court addressed the interpretation of the term "pharmaceutical substance" as defined in the Patents Act, which includes a substance for therapeutic use involving a chemical or physico-chemical interaction with a human physiological system. The court examined the statutory requirements for patent term extensions concerning pharmaceutical substances, particularly focusing on sections 70 to 79A of the Act. It was necessary to determine whether escitalopram, as a component of the racemic mixture citalopram, could be considered a distinct pharmaceutical substance eligible for a separate patent. The court also considered the relevance of the Australian Register of Therapeutic Goods (ARTG) and the requirement that the pharmaceutical substance must be included in the register.

The court reasoned that escitalopram, while being a component of citalopram, exhibited distinct pharmacological properties that warranted its recognition as a separate pharmaceutical substance. It distinguished escitalopram from citalopram based on its significantly higher potency and specific therapeutic effects. The court held that escitalopram could be patented independently, as it met the criteria for a distinct pharmaceutical substance under the Act. The decision underscored the importance of the chemical and therapeutic distinctiveness of escitalopram from citalopram, allowing for separate patent protection. Consequently, the court ruled in favour of Lundbeck, affirming the patentability of escitalopram.