Pre-Exposure Prophylaxis or PrEP

Pre-exposure prophylaxis (PrEP) involves putting HIV negative people on antiretroviral drugs (ARV) with the aim of protecting them from HIV infection. This blog looks at some of the pros and cons of PrEP.

Wednesday, July 20, 2011

ARV Resistance: the Ultimate Pharmaceutical Industry Wet Dream

Few in the pharmaceutical industry wish to discuss the important issue of resistance developing to antiretroviral drugs (ARV). Resistance inevitably develops but the question is, at what rate? In high prevalence countries, which are also resource poor countries, there are very few types of ARV available. So when resistance develops to the common ones, there are few alternatives left and most of them are prohibitively expensive.

Ed Susman discusses resistance, which seems to develop rapidly in the US. The US has one of the highest average spends on healthcare in the world. People on ARVs there are monitored carefully and their regime is changed relatively quickly when the patient is not responding for any reason. This is unlikely to happen in developing countries, where most detailed monitoring is beyond their reach, for a variety of reasons.

Another thing Susman discusses is transmitted resistance, which means that a person with a resistant strain of HIV can transmit their resistance, along with the virus. Therefore the current rate of resistance could rise sharply, especially where HIV transmission rates are high.

This might be an acute problem in countries where there is talk of rolling out PrEP on a large scale or using HIV treatment as a means of preventing HIV transmission. Huge numbers of people will be on ARVs with very little monitoring and probably fairly lax adherence. Given that it takes many months to discover non-response to drugs and provide a change of regime in some rich countries, this problem is going to be a lot more challenging in poor countries.

Susman does not discuss resistance in a context where some, perhaps a lot, of HIV is transmitted non-sexually. If large numbers of people are being treated in unsterile conditions and HIV happens to be transmitted nosocomially, the rate of resistance to common drugs, usually the only affordable ones, could increase and leave many patients beyond help.

As one of Susman's informants says "individuals infected with HIV who respond to antiretroviral regimens can anticipate a life expectancy that is similar to uninfected people, because of the number of treatment options currently available. However, in these young people who already have lost one or two or more classes of drugs, [there will be] limited options for therapy". The options will be a lot more limited in African countries, if there are any options.


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