A US federal judge has ordered the Food and Drug Administration to deliver a verdict on a version of human growth hormone developed by Novartis’ generics subsidiary Sandoz that is a copy of Pfizer’s Genotropin (somatropin) product.

The product, called Omnitrope, is a so-called ‘biogeneric’ product, more accurately referred to as a ‘follow-on biologic’ in the USA or ‘biosimilar’ in Europe, which have proved a headache for regulators. But with Sandoz on the brink of becoming the first company to successfully bring a biogeneric to market in Europe, all eyes are on the FDA’s lack of progress in regulating the sector.

The main problem for the agency has been the lack of a defined regulatory route to approval for these products, mainly because it is not possible to make a biologic by one production process that is completely identical to another using a different process. This means that classical notions of bioequivalence – which underpin the generic drug market – do not apply.

Europe cleared its regulatory framework last month, although there are still some areas of contention, notably the generic names of biosimilar drugs, pharmacist substitution of a biosimilar for an innovator product, confidentiality of innovator dossiers and the balance between pre- and post-marketing studies in supplying safety and efficacy data.

But the FDA is lagging far behind, saying that it will not finalise its own guidance on approval criteria for follow-on biologics until a voluntary code of practice has been developed by industry. This stance could set back approval of such products until 2009, according to Datamonitor.

Datamonitor also estimates that biologics with annual sales of around $20 billion are out of patent and vulnerable to generic competition, and uptake of biogenerics is expected to be rapid as the at-risk drugs - which as well as hGH include insulin, erythropoietin, interferons and colony stimulating factors - tend to carry a high price tag.

Omnitrope was filed for approval in the USA in July 2003, but has been languishing at the FDA ever since, and Sandoz decided to take matters into its own hands last September, filing a lawsuit against the FDA in a bid to force it into action.

A Wall Street Journal report suggests that the judge in the case criticized the FDA for its hesitancy in handling follow-on biologics.