Questionable Witnesses and Unquestionable Reasoning: Observations on Merck v. Glenmark

Wednesday saw the Delhi High Court deliver judgement (PDF) in Merck v. Glenmark, a two-year-long patent infringement case concerning Merck’s patented anti-diabetic Sitagliptin (marketed under the brand name Januvia). This represents the first judgement on merits to decide the fate of a Dipeptidyl Peptidase-4 (DPP-4) inhibitor, a class of drugs that are becoming increasingly significant (both from an economic and a public health perspective) in a country of more than 60 million diabetics.

Sitagliptin Phosphate Monohydrate

Image from here.

Shamnad culled out the key takeaways from the judgement in his post – the fact that it disproves Western caricatures of India as an anti-IP jurisdiction, Glenmark’s reliance on dubious expert witness testimony, the dismissal of any “public interest” justification for patent infringement, and the fact that the whole thing got wrapped up within 3 months of the Supreme Court order mandating expedited disposal (miracles do happen!).

Over this post, I summarise and evaluate the court’s treatment of Merck’s case that Glenmark infringed upon its patent, and Glenmark’s argument that the Sitagliptin patent was liable to be revoked.

Before that, here are some general observations on the judgement as a whole:

  • As Shamnad noted, it’s extremely well-reasoned and makes for crisp reading, despite its page-count.
  • As if to pre-emptively quash any Robin Hood-esque public interest argument Glenmark could mount, the court makes it a point to take note of Merck’s pricing policy for the drug, marketed as Januvia. The court also refers to Merck’s patient access programme with approval. (¶6)

The court issued a permanent injunction and restrained Glenmark from manufacturing any product claimed by the ‘816 patent. However the court did not see it fit to order damages/lost profits since no case was made out by Merck. Nonetheless, Glenmark was ordered to pay Merck’s attorney costs for the proceedings. This case goes to show that “at risk” strategy for launching generics is no longer lucrative.

Dramatis Personae

Central to the arguments on both sides were the following patents:

  • IN 209816

This was the subject of the dispute (the “suit patent”), and contained 20 claims.

  • EP 1654263

This was a patent granted to Merck by the EPO for Sitagliptin Phosphate Monohydrate (the “’263 patent”).

  • Indian Patent Application Nos. 5498/DELNP/2005, 1130/DELNP/2006, 2710/CHENP/2008, 4922/DELNP/2010

These were patent applications (“phosphate applications”) made by Merck concerning the phosphate monohydrate salt of Sitagliptin.

Questions before the court

On the patent front, there were two broad questions that needed answering:

First, did Glenmark’s manufacture and sale of Sitagliptin Phosphate Monohydrate infringe upon the suit patent?

Second, does Glenmark’s counterclaim seeking revocation of the suit patent hold water?

(As an aside, I’m a little curious as to why the bench chose to structure the judgement in the way that it did. While I understand that the question of revocation arose out of a counterclaim, wouldn’t it have made more sense to examine it prior to going into the question of infringement? It appears to me that the court could have saved considerable time and expense if it turned out that Glenmark’s counterclaim held out, rendering the question of infringement moot. However, I have no idea how trial proceedings take place, and would be extremely interested to hear an explanation for this.)


Glenmark’s argument on infringement rested on two limbs:

Sitagliptin/Sitagliptin Hydrochloride v. Sitagliptin Phosphate Monohydrate

As readers may know, Merck had filed a patent application in India for Sitagliptin molecule and subsequently filed another separate patent application claiming Sitagliptin phosphate itself. While the product patent Sitagliptin was granted in India as the ‘816 patent, the subsequent Sitagliptin phosphate salt patent (5948/DELNP/2005) was abandoned due to Sec 3(d) rejections. Glenmark relied on this fact and argued that since Merck had filed two separate patents for Sitagliptin and Sitagliptin monophosphate, they were chemically different products and that Merck had no rights over Sitagliptin phosphate and their rights were limited to Sitagliptin free base simpliciter. (¶8) Further, Glenmark contended that they were not infringing the Sitagliptin product patent and were only within the scope of the second salt patent which was abandoned anyway. (¶11) The court (like Madhulika) did not buy this argument, because Sitagliptin Phosphate Monohydrate tablet which is 128.5 mg in fact, contains 100 mg of Sitagliptin Free Base and is the active moiety. (¶13, ¶49, ¶76) The court also accepted Merck’s argument that further patents (such as the ‘263 patent and the phosphate applications) were selection patents that did not ipso facto lead to the exclusion of the phosphate salt from the protection of the suit patent. (¶51)

Manufacture of Sitagliptin Phosphate Monohydrate without using patented molecules

Glenmark also claimed to use a manufacturing process that used neither the free base nor the hydrochloride salt as a raw material or an intermediate. (¶11) However, this claim was rejected by the court as being completely unsubstantiated by the evidence on record. (¶73)

Glenmark also argued that the transformation of the phosphate compound into free base form happened inside the body, and therefore could not constitute infringement. (¶48)

This, too, was rejected by the bench, which held that Sitagliptin is not formed by a natural process, but is administered into the body. (¶75)


Lack of inventive step [S. 64(1)(f)]

Glenmark argued that the suit patent is obvious in light of earlier patents disclosing DPP-4 inhibitors, as well as other patents disclosing various other portions of the Sitagliptin coupound. Glenmark’s argument seemed to hinge on the assertion that the suit patent lacked an inventive step merely because the claimed molecule could be manufactured by a synthesis of compounds claimed in other patents. (¶¶81-83)

Merck, in an extremely well-reasoned rebuttal to this argument that was accepted in whole by the judge, showed that Glenmark’s case rested on the selection and combination of previously patented compounds in a manner that was explained only by assuming that it benefited from the hindsight knowledge of Merck’s patented compound to cherry-pick patents and even the substituents on the alleged constituent compounds. (¶84-86)

The most damning piece of evidence, however, came from Glenmark’s own witness (DW-2, the same witness whose testimony was called out repeatedly by the judge), who admitted to a hindsight-based prior art analysis. (¶87, ¶95)

On the whole, the judge took a good amount of space and time (about 20 paragraphs) to rip apart Glenmark’s prior art search, and its relevance to the Sitagliptin patent.

Lack of industrial applicability [S. 64(1)(g)]

This argument flowed from Glenmark’s previous assertion that the free base was unstable and could not be delivered as a drug. In ¶98, however, the judge holds that Sitagliptin free base is the moiety that possesses the therapeutic effects claimed.

Insufficient disclosure and broad claiming [S. 64(1)(h) and S. 64(1)(i)]

Again, this argument stemmed from the fact that the hydrochloride salt was the only form in which the preparation of Sitagliptin was exemplified in the disclosure. Glenmark also argued that the suit patent only teaches the hydrochloride salt, and therefore its coverage ought to be restricted to the hydrochloride, and not the free base or the phosphate. (¶45)

This was countered on fact by Merck, with support from expert testimony. (¶59)

The argument on broad coverage was that the claim was embodied in the form of Markush structures, which could potentially cover billions of molecules within the broad class claimed.

In ¶102, the court holds that Markush structures are accepted in a wide variety of pharma patent claims, and that the claims can neither be held to be overbroad nor to disclose too little information.

Non-disclosure of subsequent applications [S. 64(1)(j)] and of foreign proceedings [S. 64(1)(m), S. 8]

Glenmark argued that Merck’s failure to keep the patent office informed of its applications for the phosphate salt amounted to violations of the Act that merited revocation of the suit patent. Here, again, the court refused to entertain Glenmark’s contention.

Glenmark’s counsel contended that the term “may” mentioned in S 64 of the act should be construed as “shall”. However the court did not agree with the defendant’s position and emphasized that revocation did not proceed automatically from a violation of S. 64 of the Act, but was instead a discretionary power to be exercised by the court if it was satisfied with the facts and circumstances of the case, and if the omission to furnish information was deliberate. (¶106)

All in all, it appears to be quite a comprehensive victory for Merck on all fronts. Further, it does not appear that any of the issues decided against Glenmark contain an iota of doubt in reasoning. It seems highly unlikely, therefore, that the ruling would be overturned on any ground.

Balaji Subramanian

Balaji Subramanian

Balaji is a third year student at NALSAR, Hyderabad. He is currently an editor of the Indian Journal of Intellectual Property Law. He is fascinated by technology law and IP law, and is an active member of NALSAR's Technology Law Forum. When he isn't doing law school things, he wanders the country looking for quizzes to participate in. He can be emailed at [email protected]

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