Therapeutic Options When Changing Antiretroviral Therapy

Recommendations for changes in treatment differ according to the indication for the change. If the desired virologic objectives have been achieved in patients who have intolerance or toxicity, there should be substitution for the offending drug, preferably using an agent in the same class with a different toxicity or tolerance profile. If virologic objectives have been achieved, but the patient is receiving a regimen not in the preferred category (such as two NRTIs or monotherapy), there is the option to continue treatment with careful monitoring of viral load or to add drugs to the current regimen to comply with strongly recommended treatment regimens. As discussed above, most authorities feel that treatment with regimens not in the strongly recommended category is associated with eventual failure and recommend the latter tactic.

At present there are very few clinical data to support specific strategies for changing therapy in patients who have failed the strongly recommended regimens; however, a number of theoretical considerations should guide decisions. Because of the relatively rapid mutability of HIV, viral strains with resistance to one or more agents often emerge during therapy, particularly when viral replication has not been maximally suppressed. Of major concern is the possibility of broad cross-resistance among drugs within a class. Evidence indicates that viral strains that become resistant to one PI or NNRTI often have reduced susceptibility to most or all other PIs or NNRTIs.

Table 21 summarizes some of the most important guidelines to follow when changing a patient's antiretroviral therapy. As stated above, a change in regimen because of treatment failure should ideally be guided by results of resistance testing. Dose modifications may be required to account for drug interactions when using combinations of PIs or a PI and NNRTI (Table 18 ). In some individuals, options may be limited because of prior antiretroviral use, toxicity or intolerance. In the clinically stable patient with detectable viremia for whom an optimal change in therapy is not possible, it may be prudent to delay changing therapy in anticipation of the availability of newer and more potent agents. It is recommended that the decision to change therapy and design a new regimen should be made with assistance from a clinician experienced in the treatment of HIV infected patients through consultation or referral.

previous page | next page

return to table of contents