Last week saw yet another setback for multinational pharma companies in India, as Merck & Co failed in a bid to block Glenmark Pharmaceuticals from selling a generic version of its Januvia and Janumet diabetes drugs.
The US pharma giant filed a lawsuit against Glenmark earlier this month after the Indian drugmaker started selling copycat versions of Januvia (sitagliptin) and Janumet (sitagliptin and metformin) under the Zita and Zita Met brand names.
The High Court in Delhi has refused to impose an injunction on Glenmark’s sales of the copycat products, but has said that Merck’s lawsuit alleging patent infringement can get underway.
Merck has sold sitagliptin in India since 2008, both under its own banner and under a license by India’s Sun Pharmaceutical, which sells the two drugs as Istavel and Istamet. Sun is a co-plaintiff in the case against Glenmark.
According to the court documents, Merck sells Januvia in India for around 43 rupees per pill – around 20 per cent of its price in the US – while Glenmark’s versions are sold at a 20-30 per cent discount.
The case is yet another example in which a drugmaker has fallen foul of India’s stance on intellectual property (IP), particularly with regard to modified versions (eg salts or crystalline forms) of active pharmaceutical compounds.
At first glance, the deliberations in the Merck versus Glenmark case seem to centre on sitagliptin and sitagliptin phosphate salt, which are patented separately in the US. Merck only has a patent on sitagliptin in India, as a separate patent on the phosphate salt was abandoned, but said India’s IP laws made a separate filing unnecessary.
Glenmark has launched generics containing the phosphate salt version of the drug and argues that as a result it does not infringe Merck’s IP in India. Merck obviously takes the opposing view, arguing that the phosphate form is covered by its sitagliptin patent.
It is a mark of the complexity of India’s IP that Glenmark’s reliance on differentiation of its generic with regard to the salt form used seems to conflict with prior patent rulings in India – notably the recent judgment on Novartis’ Glivec (imatinib mesylate).
In that case, Novartis’ IP on Glivec was overturned on the grounds that the new salt form it employs was a new form of a known substance and therefore unpatentable.