Efavirenz, marketed as SUSTIVA by DuPont Pharmaceuticals, only needs to be taken once a day and is taken in combination with other HIV drugs.

It was approved in the USA last summer where it has become the only non-nucleoside reverse transcriptase inhibitor (NNRTI) - a class of HIV drug - to be included as a first line option in national guidelines.

The only other frontline drugs are combinations which include protease inhibitors which are more difficult to take.

In the last few years, the number of people in Europe and the USA who have been dying from Aids has been massively reduced due to the arrival of combination therapy - a individualised cocktail of at least three to four different HIV drugs.

The therapy has reduced the presence of HIV to undetectable levels in many patients, but many are difficult to take.

Patients often have to take different types of drug several times a day and, with protease inhibitors and some other drugs, there are restrictions on what and when patients can eat.

SUSTIVA only needs to be taken once a day and there are no restrictions on diet.

"Normal lives"

DuPont says it will help patients to lead "more normal lives" and "offers a major advance in convenience of use for people living with HIV".

In clinical trials, it has been shown to reduce HIV levels in many body fluids, including blood and cerebrospinal fluid.

Aids drugs have cut death rates dramatically in recent years

DuPont says it has also been shown to reduce HIV to below quantifiable levels in 98% of patients, including those with high viral loads.

Aids experts say this is the first time data on people with high viral loads has been so clearly analysed.

Simon Collins of the Aids Treatment Project said: "It is key to the long-term treatment success of HIV that the drug is effective on people with high viral loads."

DuPont also claims efavirenz used with two other drugs is more effective than combinations using protease inhibitors.

Professor Brian Gazzard, clinical research director of the HIV/GUM unit at Chelsea and Westminster Hospital in London, called it "a major advance in the treatment of HIV infection".

The drug, which will cost the NHS £234.65 per bottle of 90 capsules, has some side effects which include drowsiness and disorientation.

Aids treatment experts say that it may also produce hallucinogenic effects.

But DuPont says the side effects are usually "transient" and less likely to put people off taking efavirenz than those of other HIV drugs.

More choice

A spokeswoman for the Aids Treatment Project welcomed the approval of SUSTIVA, but said it had to be seen "in context".

"It has done well in trials and does add to people's options which is good since HIV is quick to develop resistance to many drugs if the combination does not reduce viral loads to undetectable levels.

"The bigger the choice available to people the better, but it must be remembered that all HIV drugs have to be taken in combination and it is very likely the other drugs taken with SUSTIVA will not be taken just once a day."

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The original of this article can be found at http://news.bbc.co.uk/hi/english/health/background_briefings/aids/newsid_358000/358023.stm.

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