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The current treatment guidelines for HIV therapy are outlined in the DHHS guidelines. Recommendations are based on whether the patient is treatment naïve or treatment experienced. The three most common classes of medications are non nucleoside reverse transcript inhibitors (NNRTI), nucleoside reverse transcriptase inhibitors (NRTI), and protease inhibitors (PI).
For treatment naïve patients there are currently three types of combinations recommended. The combinations recommended are:
- NNRTI based therapy (1 NNRTI + 2 NRTI)
- PI based therapy ( 1-2 PI's + 2 NRTI)
- Triple NRTI based regimens
Each combination has potential advantages and disadvantages. When selecting an initial therapy one has to consider:
- Co-morbidities
- Adherence potential
- Dosing convenience
- Potential drug-drug interaction
- Pre-treatment CD4 counts
- Gender
- Pregnancy potential
After assessing the above the optimal initial combination can be determined for each patient. The currently preferred specific agents within each class can be found in the April 2005 DHHS treatment guidelines.
Management of the treatment experienced patient is more complex and needs to be more individualized. First, one must determine why the initial therapy has failed. Failure can be due in part or full to many reasons, including patient adherence, drug toxicities, sub optimal pharmacokinetics, or the development of resistant strains.
Resistance testing is recommended to guide therapy in all treatment failures and should be performed within 4 weeks of stopping a previous regimen. The results of resistance testing and the patient's prior treatment history are then used to formulate subsequent therapy. Adding a drug with a new mechanism of action such as a fusion inhibitor or pharmacokinetic enhancing of protease inhibitors with ritonavir is often done at this point.
Interpretation of resistance testing and selection of regimens for the treatment experienced patient is a highly complex process and consultation with experts should be obtained.
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