A new HIV treatment will reduce the number of pills patients have to take, researchers say.

Patients prescribed Reyataz (atazanavir) would take three pills a day, compared to up to 12 if they are on similar existing treatments.

Charities said the drug offered another treatment option for people living with HIV.

Patients often have to change their medication because the HIV virus becomes resistant to current treatment.

Some patients have already been able to take Reyataz.

But doctors have had to prescribe it on an individual basis, taking responsibility for any side effects the patient may suffer.

The drug has now been licensed so it can be prescribed more widely.

‘Fulfilling lives’

Reyataz is a protease inhibitor - which inhibitors block another key enzyme which HIV requires to re-produce itself.

These drugs are given to patients as a second stage of treatment, after they have developed resistance to another class of drugs.

But other protease inhibitors can have unpleasant side effects, affecting how patient’s bodies metabolise fat.

They can develop very drawn faces, significant swelling around their abdomens or even “humps” on their backs .

Dr Margaret Johnson, clinical director of HIV/AIDS Services, Royal Free Hampstead NHS Trust, said: “HIV is now a long-term condition in the developed world so with the focus of treatment shifting to allowing patients to live more fulfilled lives.

“Reyataz is an important advance. Not only has it been shown to be as effective as the previous standard of care, but you can take it once daily and it minimises the gastrointestinal side effects - particularly diarrhoea - which have been hurdles with other protease inhibitors.”

‘Fewer side effects’

Jo Robinson, senior health promotion specialist at the Terrence Higgins Trust, told BBC News Online researchers always welcomed another drug in the arsenal to fight HIV.

She added: “One of the best things about this drug is that it appears not to cause side effects like other protease inhibitors.

“A lot of people have deformities, which occur when they take these treatments.”

Ms Robinson said taking fewer pills would also benefit patients.

“You have to take HIV drugs 95 to 100% of the time because the virus is very unforgiving.

“It doesn’t matter if it’s four drugs a day, or 20 - you have to take them every day. But it’s obviously easier if you only have to take four.”