The European Medicines Agency has adopted the first-ever positive opinion for a biosimilar product that is fully approved could be substituted for an existing biologic.

The product, Omnitrope, is manufactured by Sandoz and contains somatropin, the human growth hormone used to treat growth disturbances and growth hormone deficiency in children and adults.

Sandoz has been at the forefront of efforts to try to bring biosimilars to market, in an attempt to develop a market for lower-cost products similar to that for generic versions of conventional pharmaceuticals.

Last year, the company took the US Food and Drug Administration (FDA) to court to try to force it to speed up the development of a regulatory framework for this type of product - known there as 'follow-on biologics'. Omnitope was filed for approval in the USA in July 2003, but has been languishing at the FDA ever since.

Australia’s Therapeutic Goods Administration approved Omnitrope in September 2004 for treatment of growth disorders in children. The product was launched in Australia in November 2005.

The EMEA's Committee for Medicinal Products for Human Use (CHMP) adopted the positive opinion for Omnitrope at a meeting earlier this week.

The CHMP concluded at that meeting that Omnitrope has been shown by studies demonstrating comparable quality, safety and efficacy to be similar to a reference medicinal product already authorised in the EU, namely Pfizer/Pharmacia's Genotropin.

Meanwhile, another application to market a biosimilar version of somatropin has been filed with the EMEA by Swiss company BioPartners, which has also submitted a dossier for interferon alpha, a treatment for hepatitis.

The main obstacle to the development of biosimilar regulations has been that, in contrast to chemically synthesised drugs, it is hard to develop quality standards for biologics. In turn, this means that quality standards that could prove ‘bioequivalence', the standard measure by which a generic is shown to behave in the same way as an originator drug, are lacking.

However, Europe is well ahead of the USA in tackling this issue. The first guidelines on quality, non-clinical and clinical issues were adopted by the CHMP in December 2003, and a general regulatory guideline on similar biological medicinal products was adopted in September 2005.

The FDA's deliberations on how to develop an approval process for these products are expected to hold up launches until at least 2009, according to a recent Datamonitor report.

The market research firm said that biologic products with sales of $20 billion in 2004 are at immediate risk of generic erosion.