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  • Writer's pictureVrinda Sehgal

Pharma Trademarks Are A Different Species: Court Rejects Appeal Against Mark Derived From Same INN


Recently in the case of Sun Pharmaceuticals Ltd v. Hetero Healthcare Ltd. & Anr., the Delhi High Court rejected an appeal made by the Appellant, Sun Pharmaceuticals, claiming that the Respondent’s drug sold under the mark “LETERO” (used to treat breast cancer at an advanced stage) had infringed their trademark “LETROZ”. The Court found that both parties’ drugs contained the generic active pharmaceutical ingredient “Letrozole,” which is the international nonproprietary name (INN) of a salt used in drugs for such treatment.


The Appellant, one of the largest pharmaceutical manufacturers in the world, filed an appeal with the Division Bench of th Delhi High Court aggrieved by the order made by the Commercial Court on April 29, 2022 wherein the Court had found in favor of the Respondent, Hetero Healthcare Ltd.

The Appellant sought to permanently restrain the Respondent from using the mark “LETERO” and alleged that the Respondent’s use of the said mark in respect of pharmaceutical products amounted to trademark infringement and passing off based on its similarity to their mark “LETROZ”. They claimed that they had been using the mark “LETROZ” for a generic drug for second line treatment of advanced breast cancer since the year 2001.

The Appellant claimed that they had come across the Respondent’s drugs, containing Letrozole (the active pharmaceutical ingredient) being sold under the mark “LETERO” in 2017. The Appellant further alleged that the Respondent’s use of the mark “LETERO” was a bona fide attempt to ride on their goodwill and reputation garnered through the mark “LETROZ” in an attempt to pass off their drug as that of the Appellant’s.

The Respondent, on the other hand, argued that the term “LETROZ” was derived from the INN Letrozole’s first six letters and thus the Appellant cannot claim monopoly over use of the said word. The Respondent also pointed out that it is common practice in the pharmaceutical industry to use trademarks derived from the active pharmaceutical ingredient (API). The Respondent also argued that the term “LETERO” is a coined combination of the INN and their own mark “HETERO” and thus is a distinctive mark adopted without any mala fide intentionas as claimed by the Appellant.

Furthermore, the Respondent argued that there is no phonetic similarity between the marks “LETROZ” and “LETERO” and there can be no likelihood of confusion in the minds of the consumers.

The Commercial Court did not find any case for grant of interim injunction in favor of the Appellant. The Court also held that the Appellant cannot monopolize the INN Letrozole. It noted that, “when we compare the trade mark of the plaintiff LETROZ and that of the defendant LETERO, it is clear that there is no deceptive similarity which can confuse the doctor or the chemist…The composition are totally similar as reflected clearly on the boxes…It is beyond understanding as to how the plaintiff can stop the defendant from using Ist two alphabets when he himself is using all the 6 alphabets LETERO of the generic name i.e LETEROZOLE.”


The Division Bench of the Delhi High Court upheld the decision of the Commercial Court and found that there could be no possibility of confusion or deception in the minds of the purchasers of the drug. The Court relied on several judicial precedents including the case of Panacea Biotec Ltd. v. Recon Ltd., where it was held that, ‘when the name is derived or coined from the name of the principal ingredient being used in the manufacture of the drug, no distinctiveness or exclusiveness can be claimed by the manufacturer.’ Thus, in the present case, the Court applied the same test and found that “LETROZ” is nothing but a short name of the active ingredient Letrozole.

With regards to the claim for passing off, the Court clarified that similarity between the competing marks should be observed along with whether there is a likelihood of deception or confusion. In the present case, the Court also found that the packaging, color scheme and manner in which the marks are presented on the drugs of both the parties were “distinctly different”.

It is worth noting that the Court also held that, “In a case, where a drug necessarily has to be prescribed by a registered medical practitioner, especially, for the treatment of an ailment as serious as breast cancer, it is difficult to accept that the said medical practitioner is likely to be confused because the initial three letters of the marks – which are derived from the API – are same.Thus, the Court found that a specialized medical practitioner such as an oncologist was not likely to be confused just because the first three letters of a drug were the same, that too derived from the INN Letrozole itself. The Court also noted that the Appellant had not filed any evidence to prove that there had been any instances of confusion due to the alleged deceptive similarity between the two marks.

Dismissing the appeal, finally, the Court also clarified that an appellate court would not interfere with a trial court’s decision merely because a different view is possible. Thus, the Court stated, “As long as the view taken by the court below is a reasonable one, no interference is warranted.”


This case reflects the different approach taken in trademark disputes in the pharmaceutical industry as compared to other industries. In the pharmaceutical industry, when a trademark is derived from the active ingredient of a drug which is an INN, one particular manufacturer cannot claim monopoly over the same. The standards are set higher in the pharmaceutical industry and when matters concern life saving drugs and human health, the judiciary’s stance with regards to trademark disputes is taken with utmost care. In the present case, it is worth noting that the Court found that it was unlikely for a specialized practitioner to get confused between the two marks. Therefore, in this case, the “consumer” was not expected to be an unwary or ill-informed consumer. It is also interesting to note that the Court clarified that an appellate court shall not interfere with a reasonable decision made by the lower court merely because a different view is possible.

For any queries, please reach out to Ms. Vrinda Sehgal at


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