The Risk of Detectable HIV-1 RNA Loads or of PI or Lamivudine Resistance Is Significantly Higher in Nelfinavir-treated Patients Than in Lopinavir/ritonavir-treated Patients

Relationships between adherence to protease inhibitor (PI)-based therapy and resistance development have not been fully characterized.

Abbott scientists conducted a double-blind, randomized, controlled study of lopinavir/ritonavir (Kaletra) versus nelfinavir (Viracept), each administered with stavudine (Zerit) and lamivudine (Epivir), in 653 antiretroviral-naive, human immunodeficiency virus (HIV)-1-infected patients.

Relationships between adherence and probability of resistance development were evaluated by local linear regression or logistic regression.

Results

·         A higher risk of detectable HIV-1 RNA loads after week 24 was associated with lower adherence and nelfinavir use.

·         Among all nelfinavir-treated patients, a bell-shaped relationship between adherence and the risk of nelfinavir resistance was observed, with a maximum probability of 20% at 85%-90% adherence.

·         No lopinavir resistance was observed.

·         A bell-shaped relationship was also observed for the probability of lamivudine resistance, with a maximum probability of 50% at 75%-80% adherence to nelfinavir and of 15% at 80%-85% adherence to lopinavir/ritonavir.

Conclusions

The authors conclude, “Bell-shaped relationships between adherence and resistance were observed.”

“Irrespective of adherence level, the risk of detectable HIV-1 RNA loads or of PI or lamivudine resistance was significantly higher in nelfinavir-treated patients than in lopinavir/ritonavir-treated patients.”

Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA.

05/20/05

Reference
M S King, S C Brun and D J  Kempf. Relationship between Adherence and the Development of Resistance in Antiretroviral-Naive, HIV-1-Infected Patients Receiving Lopinavir/Ritonavir or Nelfinavir. Journal of Infectious Diseases 191(12):2046-52. June 15, 2005.

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