At long last, MannKind Corp has finally got the green light from regulators in the USA for its rapid-acting inhaled insulin Afrezza, though the green light comes with a boxed warning and the need for more studies.

At the third time of asking, the US Food and Drug Administration has given the thumbs-up to Afrezza (insulin human) to improve glycaemic control in adult diabetics. It is delivered using a small, easy-to-use inhaler at the start of a meal and dissolves rapidly upon inhalation to the deep lung, delivering insulin quickly to the bloodstream.

MannKind notes that peak insulin levels are achieved within 12-15 minutes of administration, and decline to baseline by approximately 180 minutes. The firm’s founder and chief executive, Alfred Mann, who is estimated to have put nearly $1 billion of his own money into the company, said the approval “validates the years of clinical research and commitment that powered the development of this unique therapy”.

He added that Afrezza’s “distinct profile and non-injectable administration will address many of their unmet needs for mealtime insulin therapy, and has the potential to change the way that diabetes is treated”.

The road to approval has been a very bumpy one, given that the FDA first rejected the drug in 2010 and turned it down again in 2011. Now the agency has also insisted on a number of restrictions for use.

The FDA says it must be used in combination with long-acting insulin in type 1 diabetes patients with type 1 diabetes, and it is not recommended for the treatment of diabetic ketoacidosis, or in patients who smoke. Afrezza also comes with a boxed warning that it should not be used in patients with chronic lung disease, such as asthma or COPD, because of the risk of acute bronchospasm.

The agency is also requiring four post-marketing studies - one in children, another to evaluate pulmonary and cardiovascular risks and two looking at how it works and dosage. Observers are now waiting to see if MannKind can grab a strong commercial partner for Afrezza.