Inhalable insulin? Not yet

Disappointing news recently greeted people living with diabetes. Cipla, which was working on inhalable insulin, has been denied permission by an expert committee to conduct trails on Indian patients as it felt there was insufficient preliminary data on the safety and efficacy of the trial drug. 

This is the latest in a series of setbacks in the research to find a less painful alternative to administer insulin in people suffering from diabetes. As of now, insulin is only administered through injection, often multiple times a day. 

Earlier, Pfizer did have an inhalation drug, Exubra, sold in combination with the device to administer it, but it was withdrawn in 2007. 

“The Exubra device was too big and the delivered insulin was too little,” says Anoop Misra, chairman, Fortis, Centre for Diabetes, Obesity and Cholesterol, Delhi. “One had to do several rounds of insulin inhalation to deliver what one shot of insulin could.” 

Similarly, Afrezza, developed by US-based Mannkind and which French drug-maker Sanofi agreed to manufacture and market, didn’t quite take off as expected. In January this year, Sanofi pulled out due to poor sales. Likewise, Novo Nordisk too has shelved its plans to develop oral insulin.

For over a decade now, researchers have been working to develop inhalable insulin as an alternative to injections. There is no option of an oral pill “because the insulin molecule does not get absorbed through the intestine,” says R K Singal, head of department and chairman of internal medicine at BLK Super Speciality Hospital, Delhi.

Doctors at this point in time are not quite optimistic about the idea of inhalable insulin.

“It is a product the efficacy of which we do not know,” says Singal. “We are only banking on one thing: it is less painful and, therefore, people’s acceptance will be more; it would be a more marketable and profitable product.”

That, say doctors, is not a good enough reason or approach. Before a medical product is launched in the market, they add, we need to compare it with the existing product: how effective is it in comparison, in terms of cost and benefit to people?

Inhalable insulin is a powdered form of insulin, delivered with a nebuliser into the lungs where it is absorbed — much like the asthma medicine.

But there is a problem here. To get effective control of diabetes, which is of paramount importance, you need to give a precise dose and in the inhalation method that is difficult to monitor.

The dose goes into the patient’s lungs and the percentage of it being actually absorbed by the body is unpredictable. “Just like you can’t run your car one day on petrol, another day on CNG and then on some other day on electricity, you cannot play with the amount of insulin being absorbed by the body,” says Singal.

As compared to this, the insulin injection is a definitive and precise method, adds Misra. “We cannot take chances with Type 1 diabetes,” he adds. “And in Type 2 diabetes, there are so many new drugs that small doses of insulin are not required. It normally tends to be a large dose.” 

This, he explains, would mean that something like 30, 40 or even 50 inhalations would be required. 

Besides, people who suffer from asthma and allergies or those with a runny nose cannot use the inhalation mode. In smokers and former smokers, too, the absorption is poor and, hence, the drug is not effective enough. 

Misra expresses another concern. “Any insulin,” he says, “is a growth-producing substance. If it is inhaled, it is going into the lungs and we don’t know how much of it is being absorbed and how much of it is sitting there and for how long.” 

Singal adds that though this has been a concern, nothing has been proved yet to say that insulin administered though inhalation can cause any kind of harm.

There is also the problem of cost. Inhalable insulin is far more expensive than the many formulations of injectable insulin currently available.