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Susan Darlen of Mecklenberg, NC asks:
Is there a point to continuing funding drug treatments? I ask this because with the emergence of a drug resistant strain of HIV, it seems that any drug treatment's effectiveness is on borrowed time.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, responds:
Our initial success with highly active antiretroviral therapy (HAART) in
controlling HIV-1 replication and slowing disease progression is
actually providing more, not less, incentive for antiretroviral drug
clinical development.
It is now clear that with the appropriate drugs, HIV replication can be
controlled for far longer periods than was possible even a few years
ago. We now need to develop drugs that decrease the likelihood of the
virus developing resistance and thereby sustain the proven benefit of
therapy.
Some of the approaches for overcoming drug resistance under evaluation
are:
- Increasing the potency of antiretroviral drugs available to patients.
For example, an experimental drug called Abacavir, a nucleoside reverse
transcriptase inhibitor in the same class as AZT, ddI, ddC and D4T, is
considerably more potent than the older drugs.
- Improving adherence to the drug regimens. The complicated nature of the
current antiretroviral regimens makes adherence difficult. Omitting
doses of antimicrobial medications is a recipe for inducing drug
resistance. Therefore, investigators are working to introduce regimens
that can improve adherence by decreasing the number and frequency of
pills that a patient must take each day. In this regard, an
experimental drug called Efavirenz, a potent non-nucleoside reverse
transcriptase inhibitor (NNRTI), can be given once a day in combination
with other anti-retroviral drugs. Several clinical studies also are
evaluating the efficacy of less frequent administration of protease
inhibitors. The development of less toxic combination regimens is also
being evaluated.
- Developing drugs that target other stages of the viral life cycle will
make it increasingly difficult for the virus to develop resistance. Only
2 viral proteins (i.e.reverse transcriptase and protease) are targeted
by the 11 drugs that are currently available for the treatment of HIV
infection. New drugs that target the ability of the virus to use
chemokine receptors to enter cells, and that target the viral integrase
enzyme are in development.
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