If you have used a lot of HIV drugs in the past, it can be can be more difficult to find a combination of anti-HIV drugs that will work for you. The term ‘salvage therapy’ used to be used for people with very limited treatment options.

But it has now become a lot easier for people who have taken a lot of HIV drugs in the past to find a combination of drugs that is effective. This is because new classes of drugs have been approved such as fushion inhibitors and entry inhibitors or will be approved soon  (integrase inhibitors), and more potent and tolerable drugs have been developed in the existing classes.

Until recently, the chance of achieving an undetectable viral load (below 40 or 50) if you had taken a lot of HIV drugs in the past was relatively low but new clinical practice and improved drugs are now being developed specifically for people who are having difficulty finding an effective combination of anti-HIV drugs. These advances have increased the possibility of highly antiretroviral-experienced people achieving an undetectable viral load. In fact, European treatment guidelines issued in October 2007 said that the aim of anti-HIV treatment for everybody regardless of their prior treatment experience should be an undetectable viral load.

First and second line choices of treatment are relatively straightforward in most cases as the range of classes available makes finding a new combinations simple (two nucleoside analogues and a non-nucleoside [NNRTI] can be followed by two nucleoside analogues plus a boosted protease inhibitor). For those whose first or second-line treatment has failed, different factors begin to determine which treatments can be used. Some factors, such as drug resistance, low blood concentrations of particular drugs and adherence issues, may influence the approach this time around. When changing your treatments, you and your doctor should consider the reasons previous treatments have failed, before choosing the next regimen.

Resistance testing is an important tools used in this decision as it can help to identify which drugs are most likely to be effective for you.

By using resistance testing and treatment history to select a combination that includes as many drugs that will work as possible, an undetectable viral load in people who have used a lot of anti-HIV drugs in the past is now often possible.

The development of Fuzeon (T-20, enfuvirtide) introduced a brand new class of drugs, the fusion inhibitors. It shows no cross-resistant to any of the existing drug classes and so is a crucial step towards successfully treating those with treatment experience. While T-20 must be injected twice daily, which some people find difficult, combined with newer therapies, this class has helped many people achieve undetectable viral loads.

Other classes of anti-HIV drugs have also been developed that provide important treatment options for people with HIV that has drug resistance. Integrase inhibitors offer a new mechanism for interrupting HIV’s reproduction. One such drug, raltegravir (Isentress) and it is now available for use by people who have taken a lot of anti-HIV drugs before. CCR5 antagonists are another class in development. Maraviroc (Celsentri) and vicriviroc are two drugs from this class. Maraviroc received approval in the US and Europe in 2007.

New drugs in the classes already available have or are been designed to work against HIV even if there is a lot of resistance present. If you currently have experience of multiple protease inhibitors, ritonavir-boosted darunavir (Prezista) or ritonavir-boosted tipranavir (Aptivus) have been shown to be important treatment options for people with a lot of resistance to older protease inhibitors. For many, these protease inhibitors prove to be even more effective when combined with T-20 increasing the chances of success.

NNRTIs are also entering a new generation of development with some potential new drugs looking like they might work against virus with NNRTI resistance. Etravirine (Intelence) is one such drug and it should be approved in 2008.

While the currently available drugs may be enough to manage the virus for some, others will be eagerly awaiting the approval of some of these newer therapies. Where drugs are not currently licensed, they may be accessible through clinical trials, although often certain criteria need to be met. Often, drug companies run expanded access schemes so that patients with few treatment options can obtain early access to the drugs. You will need to be eligible to obtain them, but those with extensive treatment experience are a top priority. Speak to somebody at your HIV clinic for further advice.