Regulators in the USA have rejected Boehringer Ingelheim and Eli Lilly's empagliflozin over concerns about the facility where the closely-watched investigational diabetes drug will be made.

The US Food and Drug Administration has issued a complete response letter for empagliflozin, a sodium glucose co-transporter-2 (SGLT2) inhibitor. The agency has referenced "previously-observed deficiencies" at a Boehringer facility where empagliflozin will be manufactured, stating that these need to be resolved before approval of the application.

On the plus side, the FDA has not asked Boehringer to complete any new clinical trials to support the application. The latter is based on results from one of the largest clinical registration programmes in its class, comprised of more than 10  trials and more than 13,000 people.

Boehringer and Lilly said they are committed to working with the FDA to make empagliflozin available and will be submitting a response to the CRL as soon as possible.

There is much interest in SGLT2 inhibitors where compounds remove excess glucose through the urine by blocking glucose re-absorption by the kidney. The class is currently led by AstraZeneca's Forxiga /Farxiga (dapagliflozin) and Johnson & Johnson's Invokana (canagliflozin).