In Steigerwald Arzneimittelwerk GmbH vs Assistant Controller of Patents and Designs [C.A.(COMM.IPD-PAT) 423/2022], the Delhi High Court revisited the standards governing inventive step and non-patentability objections in process claims relating to phytopharmaceuticals.

The appeal arose from the refusal of patent application number 1285/DEL/2009, entitled “Method for the production of a Plant-Based Medicament”. The subject application related to a method for producing a plant-based medicament which contains Iberis amara, Menthae piperitae folium, Matricariae flos, Carvi fructus, Melissae folium, Angelicae radix, Liquiritiae radix, Cardui mariae fructus and Chelidonii herba in the form of alcoholic extracts and a medicament produced according to this method, and its use. The Controller had rejected the claims on the ground of lack of novelty and inventive step, and non-patentability under Sections 3(d) and 3(e) of the Patents Act, 1970.

Setting aside the impugned order, the Court emphasised that general disclosures in prior art regarding the importance of a “right mixing sequence” cannot, without reasoned analysis, render a specific and technically demonstrable manufacturing sequence obvious.

The invention addressed a specific technical difficulty encountered during the manufacture of Iberogast (plant-based medicament), namely, the inability to maintain a constant and reproducible content of the lead substance osthol due to precipitation and crystal formation during production and storage. These precipitations resulted in inhomogeneity in the production batch and fluctuations in the effective substance content, thereby affecting product stability and quality over time. The Appellant asserted that this problem was not adequately addressed in the prior art and that the claimed invention proposed a specific solution through a defined sequence of mixing of individual plant extracts.

The claimed method was characterised by a three-step mixing sequence, with the first step involving the pre-mixing of Angelicae radix extract and Liquiritiae radix extract in a defined volume ratio. This pre-mixture would then be combined with selected extracts in a second step, followed by the addition of remaining extracts in a final step. According to the complete specification, the sequence and ratio of mixing were critical to inhibiting crystal formation and ensuring consistent recovery of osthol within the permissible tolerance. The Appellant relied on experimental data and examples in the specification to demonstrate that adherence to the claimed sequence resulted in stable batches, whereas arbitrary mixing sequences failed to achieve the same outcome.

The Controller reasoned that prior art documents D1 and D2 disclosed the same ingredients, similar proportions, and comparable therapeutic use, and that D1 expressly acknowledged the importance of a “right mixing sequence” for achieving product stability. On this basis, the Controller concluded that if the process disclosed in D2 was studied along with D1, a person skilled in the art (PSITA) would have sufficient motivation to arrive at the claimed method through routine experimentation. The claims were further rejected under Sections 3(d) and 3(e), on the premise that the invention amounted to the mere use of a known process and a mere admixture of known substances without any demonstrated synergistic effect.

The Delhi High Court closely examined whether the reasoning adopted by the Controller satisfied the requirements for rejecting a process claim on grounds of obviousness. The Court noted that while D1 did state that the right mixing sequence was essential for product quality, it did not disclose or suggest the specific three-step sequence or the defined pre-mixture ratio claimed in the subject application. The Court alluded that a general statement in prior art acknowledging the importance of sequence could not, by itself, render any particular sequence obvious. The Court noted that the impugned order failed to explain how the teachings of D1, either alone or in combination with D2, would motivate a PSITA to arrive at the precise sequence and ratios claimed. The reasoning in the impugned order was found to be conclusory, relying largely on the similarity of ingredients and compositions rather than on a structured analysis of how the claimed process would follow from the cited prior art references.

With respect to the objections under Section 3(d), the Court held that the Controller had failed to provide reasoning as to how the claimed method including the three steps with the specified ration was known in the view of the cited prior arts.

Similarly, the Court found the objection under Section 3(e) to be inadequately reasoned. It was noted that the claims were directed to a method of production and that the complete specification specifically attributed the improved stability and reproducibility of the medicament to the claimed mixing sequence and ratios. The Controller’s conclusion that the invention was a mere admixture resulting in aggregation of properties was found to ignore the technical teaching in the specification regarding the role of sequencing in inhibiting crystal formation and ensuring consistent recovery of the lead substance.

On this basis, the Court held that the impugned order suffered from various infirmities, including failure to apply the test for inventive step, lack of analysis of the prior art from the perspective of a PSITA, and insufficient reasoning for invoking the exclusions under Sections 3(d) and 3(e). The impugned order was accordingly set aside, and the matter was remanded to the Patent Office for fresh consideration.