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Long-term efficacy and safety of low-dose ritonavir-boosted atazanavir (ATV/r) 200/100 mg in HIV-infected Thai patients

Purpose of the study

Atazanavir is a good but expensive regimen in resource limited settings (RLS). A previous HIV-NAT study showed that a low dose of ATV/r 200/100mg once daily (QD) provided adequate atazanavir plasma concentrations in HIV-infected Thai adults. Reducing the dose would make atazanavir more accessible to those patients in need in RLS. We aimed to evaluate long term efficacy of lower dose ATV/r 200/100 mg in HIV-infected Thai adults.


HIV infected patients commencing ATV/r 200/100 mg QD in a prospective long term cohort at HIV-NAT, Bangkok, Thailand were analysed. CD4, HIV RNA, and safety parameters are performed every 6 months as part of the cohort.

Summary of results

A total of 84 (51% men) subjects with median age of 40 years and median body weight of 57.6 kg were included in this analysis. The median time of taking lower dose was 63 (IQR 39-82, range 2-237) weeks. 11/84 subjects had HIV RNA > 50 copies/mL at time of ATV/r lower dose initiation. These patients mainly were NNRTI based treatment failure. NNRTI based treatment failure. 79% used tenofovir as backbone. High ATV Ctrough (32%), hyperbilirubinemia (32%), and clinically jaundice (22%) were the main reason for using the lower dose. At time of analysis, 72/74 (97%) patients with availability of at least 1 HIV RNA at 6 months interval, had HIV RNA <50 copies/mL. The median CD4 count was significantly increased from 394 to 456 cells/mm3 (P =0.010). The median change in fasting cholesterol, triglyceride, LDL and HDL were -6 , -11, 13.8 and 4 mg/dL, respectively. However, the changes were not statistically significant exception for HDL (p=0.006). In patients previously used standard dose of ATV/r 300/100 QD, the median of bilirubin was 1.9 (range 0.1-7.7) mg/dl and it improved significantly after dose reduction (p = 0.003). Majority of the patients well tolerated to the treatment, only 9 patients, ATV/r 200/100 mg QD was discontinued due to ran out of stock (4 patients), hepatitis (2 patients), hyperbilirubinemia (1), nephrotic syndrome (1), and non-adherence (1). ATV Ctrough concentrations of ATV/r 200/100 were available in only 51 cases, all had ATV Ctrough concentrations >0.15mg/L.


Regimens with ATV/r 200mg/100mg provided adequate ATV plasma concentrations, were effective and well tolerated in HIV-infected Thai adult patients. A randomized controlled trial should be conducted to confirm our findings. This data will be benefit to a million of HIV infected in RLS.


  1. Chetchotisakd AS: Low-dose, once-daily atazanavir/ritonavir (200/100): an effective treatment for HIV-infected patients in Thailand. J Acquir Immune Defic Syndr. 49: 230-1.

  2. Avihingsanon A, van der Lugt J, Kerr SJ, et al: A low dose of ritonavir-boosted atazanavir provides adequate pharmacokinetic parameters in HIV-1-infected Thai adults. Clin Pharmacol Ther. 2009, 85: 402-8. 10.1038/clpt.2008.244.

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This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Avihingsanon, A., Apornpong, T., Kerr, S. et al. Long-term efficacy and safety of low-dose ritonavir-boosted atazanavir (ATV/r) 200/100 mg in HIV-infected Thai patients. JIAS 13 (Suppl 4), P60 (2010).

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  • Nephrotic Syndrome
  • Tenofovir
  • Atazanavir
  • Resource Limited Setting
  • Thai Patient