As any asthma sufferer knows, keeping tabs on inhalers and the medication they deliver is both vital and a pain.

Most sufferers have at least two - a 'preventer', the corticosteroids which have an anti-inflammatory action which treats the sensitivity that provokes asthma attacks in the first place, and a 'reliever', or bronchodilator, that acts short term - relaxing the smooth muscles of the lung and dilating the airways in the event of an attack.

For some whose asthma is difficult to bring under control, yet a third inhaler may be needed containing a long-acting bronchodilator.

Given the complicated nature of asthma therapy, it's not surprising that up to half of those with asthma fail to take medication correctly - either missing doses or using the wrong drug at the wrong time - taking for example a reliever on a daily basis instead of a preventer.

Compliance with the long-term preventer medication is particularly poor because it doesn't appear to have an immediate result, though it is a vital part of long-term treatment of asthma.

Missing doses means more than just succumbing to the odd wheezing session. More than 40 per cent of asthma sufferers still experience daily symptoms, meaning their condition is not well controlled and predisposing them to later lung complications, while, according to the Scottish Confidential Inquiry Into Asthma Deaths published last year, poor compliance is an important contributory factor in fatal attacks, which claim 1,500 lives a year.

Against this background, the launch of a new inhaler yesterday which combines, for the first time, two of the commonly prescribed drugs used to control asthma has been greeted with enthusiasm.

Seretide contains the long acting bronchodilator, salmeterol, and the corticosteroid, flucticasone propionate, in one inhaler. This combination, say manufacturers Allen and Hanbury, should improve compliance, help asthma sufferers to gain 24-hour control and reduce reliance on emergency therapy - as well as reducing the number of inhalers they have to keep track of.

Clinical studies on 2,700 people show that taking the two together in one 'puff' is at least as effective as taking the two drugs separately, and improves lung function as well as reducing asthma symptoms and the use of 'rescue' medication, the short-acting relievers used in an acute attack.

Because of the immediate action of the salmeterol, patients should feel the benefits of treatment within the first day which should motivate them to continue treatment.

There is also some evidence that taking the two together may have extra benefits for symptoms control compared to separate dosage.

Professor Peter Barnes, from the department of thoracic medicine at the National Heart and Lung Institute in London, says the dual-drug inhaler is a 'logical combination for patients who are not adequately controlled on low to moderate doses of inhaled steroids alone, or for those who find it difficult to comply with their inhaled steroid therapy'.

Prof Barnes also pointed out that substituting one inhaler for two should significantly decrease the cost of asthma therapy not only to the NHS - estimated at £730 million - but also to the patient who will only pay one prescription charge for the dual inhaler instead of two.

For Greta Barnes (no relation), director of the National Asthma and Respiratory Training Centre, the new product's benefits come not from the drugs themselves - both are which are part of current asthma therapy - but from the convenience and combination.

'The therapies we've got at the moment work very well if people use them properly. Seretide certainly has a role, but it's more one of convenience at the moment than a different action.'

However, seretide will not solve all problems, she adds. 'A lot of medical people don't like combination drugs, partly because it's more difficult to separate any adverse effects that may result and partly because, in this case, if you wanted to change the dose of one of the drugs, you'd have to have a new inhaler.'

Patients also won't be able to take a double puff of the combined inhaler if they experience worsening symptoms as that would be a doubling of both medications. They will still need to carry an emergency reliever to ease acute symptoms.

• Further information: National Asthma Campaign Helpline 0845 701 0203