A once-a-day drug heralded as a potential 'breakthrough' in the treatment of asthma and hay fever is to be tested on patients for the first time.

Clinical trials are to start soon on the medication which, it is hoped, will have fewer side effects than existing ones.

This news comes as a major boon for asthma sufferers rather than having to take two drugs -or use a combined inhaler - a single daily puff from their inhaler would be enough to stop the symptoms.

The compound, which is known as RPL554 is a single molecule that does both jobs and should have a better side effect profile.

Leanne Male, assistant director of research at the leading charity Asthma UK, said 'There hasn't been much progress recently with alternative, effective and practical treatment options for a wide range of people with asthma and hay fever. However, by combining anti-inflammatory properties and the ability to overcome airway narrowing in a single long-lasting drug administered via the nose, RPL554 could offer real hope of a significant breakthrough. 'Therefore we eagerly await the results of this first clinical trial in humans' Male Added.

Up to 60 men and women with asthma and hay fever will test the drug in the Netherlands at the Centre for Human Drug Research.

These preliminary trials for safety and efficacy will be completed early next year. If successful, they will be followed by tests involving hundreds of patients. The drug could be available in three to four years' time.

The drug was invented by Sir David Jack, the former research director at drug giant GlaxoSmithKIine who developed many asthma drugs currently in use.

In contrast, current treatments for asthma and hay fever sufferers are beta-agonists, which open up the airways, and inhaled steroids, which dampen down the inflammation that causes irritation. They are either taken together or singly. However, those treatments have serious side effects, including possible harm to the cardiovascular system and the 'shakes' reported by many patients from excess use.