Shire Pharmaceuticals has launched a lawsuit against Nostrum Pharmaceuticals after it made public plans to launch a similar version of Shire's epilepsy drug Carbatrol.
Nostrum, a privately owned company based in New Jersey, filed a new drug application for a generic version of the 300mg dosage strength of Carbatrol.
Shire, which launched its Carbatrol drug in 1998, said it had served Nostrum with a complaint for patent infringement but would not go into details. A spokeswoman said its patents on the drug - which has made about $164m of sales since its launch - did not expire until 2016. "Our lawyers have looked at the dossier [from Nostrum that has been filed with the US Food & Drug Administration] and believe it infringes patents," she said.
The move is not a great surprise, however, since the FDA announced last summer that an unnamed drug manufacturer had asked it to approve a copycat version of Shire's epilepsy treatment.
Carbatrol is one of Shire's main drugs and produced sales of $11.6m in the third quarter of last year. The company estimates it has about a 40 per cent market share.
The spokeswoman also said yesterday that the filing centred only on the 300mg strength of the drug and did not affect its 100mg or its 200mg products.
The 300mg strength, she said, made up about half the total sales Shire has so far recorded from Carbatrol.
The company's response to Nostrum's filing triggers a 30-month stay of approval - meaning the earliest date a generic version of the drug could be launched, if cleared by the court, is January 2006.
Shire's biggest selling drug is its hyperactivity drug Adderall XR, which accounts for about half of its sales. It is also battling to prevent generic versions of that drug hitting the market. At the end of last year, it announced it was suing the US drug maker Impax, which signalled it was developing a copy of Adderall XR. It has already launched proceedings against Barr, another US company developing generic Adderall.