A US district judge has turned down Danish drugmaker Novo Nordisk's motion for a

preliminary injunction that would have blocked further sales of Pfizer’s inhaled insulin Exubera.

The injunction request formed part of Novo’s patent infringement lawsuit filed against Pfizer in August, which alleges that Exubera infringes on its inhaled insulin patents and that sales of Exubera may cause “irreparable harm” for future sales of Novo Nordisk’s experimental inhaled insulin, AERx, and to the company’s reputation. The latter product is not expected to be launched before 2010 or 2011.

In his ruling, Judge Leonard Sand noted that preventing “the release of a new and less invasive treatment for diabetes would quite obviously be contrary to the public interest.” However he also noted that the evidence and arguments given by both sides “raises substantial questions as to the alleged infringement by Pfizer” and that issues of infringement and validity “will be best served through closer inspection at trial.”

Novo "remains confident"

It is the latter point that encouraged Novo to issue a statement saying that it does not regard the ruling “as impairing the strength of our underlying case,” plus it involves only one of the five patents at issue in the lawsuit. The company added that it “remains confident" in the strength of its patents, and looks forward to "a full trial on the merits of the infringement case against Pfizer.” A trial date has yet to be set for the suit.

On the other hand, Pfizer said that the court’s decision is good news for patients because it allows Exubera to remain on the market as an important option for the treatment of diabetes.

Exubera, which was developed with Nektar Therapeutics and is the first approved non-injectable insulin product, received the green light from the US Food and Drug Administration in January and Pfizer began marketing the drug through diabetes specialists in July. However it is planning a much wider marketing campaign from March.

The effect on Novo of this product is clear, in that 70% of its revenues stem from insulin injection. When patients have the option to switch from injections to Exubera, the financial cost to the Danish firm is not hard to imagine.