Insulin Exubera - an update
Since we first published our document on inhaled insulin in 2003, a lot has happened. Inhaled insulin has been studied in clinical trials involving over 3,000 adults and has been approved for use by the drug licencing authorities in Europe and America. Insulin Exubera is the first of these products to come to the market.
The difficulties surrounding the development and production of this inhaled insulin is illustrated by the fact Insulin Exubera was jointly developed by two large pharmaceutical companies, Pfizer inc. and Sanofi-Aventis. The inhaler device was developed by a third company Nektar Therapeutics. Pfizer has since purchased the full global rights to the drug and Exubera will therefore be marketed solely by Pfizer.
Insulin Exubera is a form of short acting insulin delivered by inhaler which is taken before meals. The trials have shown that insulin delivered by the inhaled route is as effective as the short acting insulin delivered by injection.
The insulin is inhaled as a dry powder which is absorbed via the lungs and thereby into the bloodstream.
Inhaled insulin does not at present substitute for long acting or basal insulin which may also be required for good control.
One of the many questions which researchers asked is ‘does inhaled insulin work long-term’ and ‘does it harm the lungs‘. Studies over a four year period have shown no deterioration in lung function as well as sustained efficacy. It must be understood that longer term safety data will only result from clinical use in patients.
The need to perform these studies explains why this product, which has been spoken of for many years, has taken so long to reach regulatory approval. Over three thousand patients have tried Exubera insulin in these clinical trials.
No. It has been approved for use by those with Type 1 or Type 2 diabetes who require short acting insulin.
Exubera is supplied in unit dose blisters containing 1 mg and 3 mg of human insulin. The recommended starting dose is based on this formula:
Body weight (kg) x 0.15 mg/kg = total daily dose in mg
The total daily dose is then divided into three pre-meal doses.
1 mg of Exubera is equivalent to 3 IU of human insulin injected subcutaneously (sc).
3 mg of Exubera is equivalent to 8 IU of human insulin sc.
The dosing is complex and 3 of the 1mg blisters does not equate to a 3 mg dose.
The dose should be inhaled within 10 minutes before the start of a meal.
The target groups for inhaled insulin have not yet been clearly defined. However people who require assistance for injections, those who are ‘needle phobic’ and people who travel a lot may benefit.
During clinical studies it was observed that people treated with Exubera may have a mild to moderate cough which often disappeared with continued use. Small differences in lung function which occurred without symptoms, were also noted, though these changes were not progressive. Hypoglycaemia has been described and is more frequent in smokers in whom the use of this medication is contraindicated.
- Poorly controlled or severe asthma
- Severe Chronic Obstructive Lung Disease (Chronic Bronchitis and Emphysema)
- Active smokers
- Pregnant women
Patients must not smoke during Exubera therapy and must have stopped smoking six months prior to initiating treatment. There is an increased risk of hypoglycaemia in smokers.
At the time of writing Exubera has not been launched in the UK though the granting of a European drug licence is a promising start. The drug would also have to be approved by NICE - the National Institute for Clinical Excellence, which would look at the evidence from clinical trials and decide whether to recommend the preparation for use in the NHS. This advice will be based on clinical efficacy and safety as well as ‘cost-effectiveness’. Inhaled insulin will almost certainly be more expensive than conventional injected insulin. One of the questions NICE will examine, is ‘which patient groups would benefit from using inhaled insulin’.
As this is the first time this device will be used by healthcare professionals we anticipate that the manufacturing company Pfizer Ltd will provide education and support for use of the inhaler.
This has not been made public as yet.
It is anticipated that Exubera will be available for prescribing in the UK from May 2006 though the launch date has yet to be confirmed.
Dr Nishan Wijenaike
West Suffolk Hospitals NHS Trust