New inhaler for asthma control

ASTHMA IS a chronic, inflammatory lung disease, characterised by recurrent breathing problems that vary over time and in severity. During an asthma attack, the mucosa lining of the airways swells , muscles around the airways tighten (bronchoconstriction) and mucus clogs the tiny airways of the lungs, making breathing difficult.

Asthma cannot be cured, but it can be controlled in 95 per cent of the people suffering from it. Several types of medication are used to treat asthma, of which the two main classes are preventers and relievers. Inhaled corticosteroids, which suppress underlying inflammation, are currently the most effective preventer therapy. Relievers are generally effective only on symptoms and taken whenever a patient encounters breathing difficulty. Common relievers are the Beta agonists (bronchodilators) which artificially relax the airways.

For most patients, the effective management of asthma requires both preventer and reliever. A landmark study published in 1997 showed that a combination of the bronchodilator formoterol and the corticosteroid budesonide, taken through a single inhaler, provided best management for patients with moderate to severe asthma. This study also showed that this combination improved patients' lung function and reduced both day and night-time symptoms.

It has also been shown that inhaling the medication in the form of dry powder is more effective than as an aerosol, since some of the powder reaches the airways while most of the aerosol spray gets dispersed in the mouth. However, the dry powder inhalers currently in use here are obsolete in design and deliver less than 10 per cent of the powder to the lungs.

The international pharma company AstraZeneca, which has one of its R & D labs in Bangalore, has recently come up with a novel design of inhaler which assures delivery of as much as 30 per cent of the drug dose deep into the lungs. The device, Symbicort Turbuhaler, has been developed by Thomas Sandstrom University Hospital , Sweden and Dr. Lars Borgstrom , Astra Zeneca R & D at Lund.

The inhaler has a reservoir at the bottom for the drug powder. A twist grip, when turned forth and back, loads a single dose into the inhalation chamber above through a rotating dosing disc which determines the dose of medication. Scrapers above the disc ensure precise dosing by removing excess amounts of drug. The measured amount of drug travels through an inhalation channel to the mouthpiece , which is specially designed with spiral channels to deaggregate the dose to respirable particles and propel them deep down into the airways. A numerical dose counter allows the patient to see how many doses are left. The background colour of the dose counter is red for the last 20 doses. The new inhaler has been found to deliver uniform doses throughout the whole dosing interval at a constant budesonide to formoterol ratio.

N. N. Sachitanand

in Bangalore

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