First Permanent Injunction Granted in a Patent Infringement Suit in India

Hon’ble Justice Mr. A.K. Pathak on October 07, 2015 granted the first ever permanent injunction in a patent infringement suit under the Patents Act 1970. The detailed judgment of 133 pages is in relation to the patent infringement action by Merck against Glenmark with respect to patent number 209816 which covers the type-II diabetes drug sitagliptin.

The judgement restrains the Defendant by a decree of permanent injunction from making, using, selling, distributing, advertising, exporting, offering for sale or deadline in sitagliptin phosphate monohydrate or any other salt of sitagliptin in any form, alone or in combination with one or more other drugs. The Plaintiff has also been entitled to actual costs of the proceedings under the order.

While Merck had claimed infringement of its 209816 patent, Glenmark argued that the product sitagliptin phosphate monohydrate being manufactured by them was actually not covered by the suit patent due to which their activities were not infringing. In addition, Glenmark claimed that Merck’s patent was invalid.

The Hon’ble Court held that since the patent relates to an invention of a chemical molecule/ compound in the medicinal field and is of a highly technical nature, the Court has to go by the opinion of the experts in the field and is not to impose their views over the views of the technical experts, more so when the Judges are not experts in the chemical/medicinal field.

The Hon’ble Court also discredited the independent technical expert of the Defendant as in the opinion of the Court said expert had taken contradictory stands which were in conflict with what was stated in his own publications (e.g. patent documents in which he has been named as an inventor) and in the publications of the Defendant. The Court also observed that the Defendant’s expert witness had a personal interest in sitagliptin since he was named as an inventor in a patent application related to sitagliptin pterostilbene phosphate. Furthermore, the Court observed that the Defendant’s expert witness gave evasive replies to questions which would inconvenience the Defendant. The Court found the Plaintiff’s independent technical expert’s testimony more favourable and reliable and found no reason not to accept the explanation provided by him.

On the question of whether sitagliptin phosphate monohydrate is covered by the suit patent since the suit patent exemplified only the hydrochloride salt of sitagliptin, the Hon’ble Court conceded with the Plaintiff’s independent expert’s testimony that the conversion of a salt to a free base and the free base to another salt was a very basic chemical transformation taught in all sophomore organic chemistry classes. Moreover, the suit patent claims sitagliptin and all its pharmaceutically acceptable salts and the phosphate salt is mentioned as a preferred salt in the specification.

The Court further observed that the Defendant’s technical expert and also the Defendant themselves in their own patent applications relating to sitagliptin have admitted that the salts of sitagliptin are generically encompassed within the scope of the suit patent which also discloses a process for the preparation of the sitagliptin and related compounds. Therefore, sitagliptin phosphate monohydrate is generically disclosed in the suit patent.

On the question of infringement, the Hon’ble Court held that a comparison of the Plaintiffs’ and Defendant’s package insert shows that all the products contain the same compound, i.e, sitagliptin phosphate monohydrate, a DPP-IV inhibitor used for the treatment of type II diabetes. Distinguishing the facts of the present case from those in F Hoffman La Roche v Cipla Ltd. (2012(52) PTC 1(DEL), the Court held that the Plaintiffs in the present case have not sought to establish infringement based on packaging and product inserts alone but also based on ocular and other documentary evidence on record.

The Court also held that the Defendant cannot conveniently disown what has been written on the packagings and the product inserts, which is a disclosure to the public at large including the doctors and consumers of the drug, about the contents used and the utility of the drug.

The Court stated that the use of sitagliptin free base alone in sitagliptin phosphate monohydrate tablet by the Defendant amounts to infringement of the suit patent. All the literature on record indicates that sitagliptin is the DPP-IV inhibitor. It is the sitagliptin free base which is the DPP-IV inhibitor and phosphate salt is used for the delivery of sitagliptin the body. Therapeutic efficacy is not enhanced by sitagliptin phosphate monohydrate since it is sitagliptin itself which is the active moiety and is effective for inhibiting DPP-IV enzyme and is useful for the treatment of type II diabetes. Sitagliptin phosphate monohydrate has enhanced properties in the sense that it has improved physical and chemical properties, but the active moiety is sitagliptin.

On the contention of the Defendant that they were using a process for the manufacture of sitagliptin that was different from the process used by Merck, the Court that no such different process was disclosed in the written statement and counter claim filed by the Defendant and no employee of the Defendant appeared as a witness to prove such a process. The process which was introduced in the evidence of the Defendant’s independent technical expert was not duly proved because he did not have occasion to verify said process having not monitored the manufacturing at any stage or having not involved himself in such a manufacturing process. Further, the independent technical expert did not personally analyse the products of the Defendant so as to verify the process.

The Defendant’s contention that Plaintiffs ought to have proved that Defendant was deploying the same process was considered inadmissible as it was the Defendant who took the plea of using a different process and therefore, should have proved the same, more so when the products of the Plaintiffs and Defendant contain the same chemical compound.

On the issue of obviousness of the suit patent the Hon’ble Court held that the onus to establish obviousness is on the Defendant which they failed to discharge by leading positive evidence. The technical expert of the Defendant has admitted to hindsight which is not permissible in an obviousness analysis. Further, the Plaintiff’s expert pointed to the non-obviousness of the suit patent in his affidavit which opinion remained unshattered in his cross-examination. Mere comparison of chemical structure is not sufficient and picking up parts of a chemical structures of different patents and clubbing them is also not sufficient as this appears to have been done based on hindsight.

On industrial application, the Hon’ble Court held that compounds that are derived from the suit patent will be a product as required under the provisions of the Patents Act and it cannot be denied that sitagliptin free base has therapeutic utility and sitagliptin phosphate monohydrate has better physico-chemical characteristics. Further, sitagliptin phosphate monohydrate is generically covered in the suit patent. There is no requirement under the law that the product has to be under a manufacturing process at the time a patent is granted.

On the issue of insufficient disclosure and broad claiming by way of Markush claims, the Hon’ble Court held that the Markush claims of the suit patent are not different from other patent documents (including those of the Defendant and their expert) which also contain Markush claims.

The suit patent is addressed to a person skilled in the art and not to a lay person. The Defendant themselves acknowledge in their patents that sitagliptin and its pharmaceutically acceptable salts are disclosed in the suit patent. The Defendant cannot be permitted to blow hot and cold in the same breath.

On the ground of non-compliance with section 8 of the Patents Act, the Hon’ble Court was in agreement with the decision of the Divisional Bench in Sukesh Bhel & Anr. Versus Koninklijke Phillips Electronics, that the power of the Court to revoke the patent on the ground of Section 8 violation is discretionary. The Court further ruled that no evidence was led by the Defendant to show that the non-disclosure of information was deliberate or for malafide reasons.

On public interest, the Hon’ble Court held that sale of the drug by the Defendant at a price lower than that of the Plaintiff cannot be a ground to decline injunction against the Defendant. The Court also held that public interest could not be a ground for denying infringement in the instant case as sitagliptin is not the only type II diabetes drugs in the market. There are several other DPP-IV inhibitors available, including, teneligliptin which is also manufactured and marketed by the Defendant.

In view of the foregoing, the validity of the patent was upheld and a permanent injunction was granted.


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