Diabetics in the USA hoping to be rid of some of their daily insulin injections will have to wait a little longer, after the US Food and Drug Administration (FDA) extended its review period for Pfizer’s inhaled insulin Exubera by three months.

The agency said it needed the extra time to review additional technical chemistry data submitted on the product. If approved, Exubera could be used in place of short-acting insulin injections taken before mealtimes, although most diabetics will still need to inject themselves with a long-acting insulin to provide background levels of the hormone.

Last month, an FDA advisory committee voted in favour of approving Exubera for both forms of diabetes [[14/10/05a]], despite doubts being raised about its efficacy in type 1 diabetes in an earlier FDA briefing paper [[09/09/05a]]. It has also been recommended for approval in the European Union [[14/10/05a]].

Pfizer and its European partner for Exubera, Sanofi-Aventis, originally expected to seek approval of Exubera in 2001, but suffered a setback after seeing small declines in lung function in some patients taking the drug [[03/05/02b]]. The companies have since generated longer-term safety data on the product that they claim demonstrate its safety [[15/06/05d]].

Exubera has been developed using technology from drug delivery specialist Nektar Therapeutics.

Even with the delay, Pfizer, Sanofi-Aventis and Nektar have a good lead over rival companies developing inhaled insulin products. Following behind include inhaled insulins from Eli Lilly/Alkermes and Novo Nordisk/Aradigm - both in Phase III testing - and a product from Mannkind, which is in Phase II.

Analysts have suggested that the first non-injectable insulin to reach the major pharmaceutical markets could quickly achieve sales in excess of $1.5 billion dollars a year.