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- Rekić, Dinko, 1984, et al.
(författare)
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Bilirubin-A Potential Marker of Drug Exposure in Atazanavir-Based Antiretroviral Therapy
- 2011
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Ingår i: AAPS Journal. - : Springer Science and Business Media LLC. - 1550-7416. ; 13:4, s. 598-605
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this work was to examine the atazanavir-bilirubin relationship using a population-based approach and to assess the possible application of bilirubin as a readily available marker of atazanavir exposure. A model of atazanavir exposure and its concentration-dependent effect on bilirubin levels was developed based on 200 atazanavir and 361 bilirubin samples from 82 patients receiving atazanavir in the NORTHIV trial. The pharmacokinetics was adequately described by a one-compartment model with first-order absorption and lag-time. The maximum inhibition of bilirubin elimination rate constant (I (max)) was estimated at 91% (95% CI, 87-94) and the atazanavir concentration resulting in half of I (max) (IC50) was 0.30 mu mol/L (95% CI, 0.24-0.37). At an atazanavir/ritonavir dose of 300/100 mg given once daily, the bilirubin half-life was on average increased from 1.6 to 8.1 h. A nomogram, which can be used to indicate suboptimal atazanavir exposure and non-adherence, was constructed based on model simulations.
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| 2. |
- Röshammar, Daniel, 1979, et al.
(författare)
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Non-linear mixed effects modeling of antiretroviral drug response after administration of lopinavir, atazanavir and efavirenz containing regimens to treatment-naive HIV-1 infected patients
- 2011
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Ingår i: Journal of Pharmacokinetics and Pharmacodynamics. - : Springer Science and Business Media LLC. - 1567-567X .- 1573-8744. ; 38:6, s. 727-742
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this analysis was to compare three methods of handling HIV-RNA data below the limit of quantification (LOQ) when describing the time-course of antiretroviral drug response using a drug-disease model. Treatment naive Scandinavian HIV-positive patients (n = 242) were randomized to one of three study arms. Two nucleoside reverse transcriptase inhibitors were administrated in combination with 400/100 mg lopinavir/ritonavir twice daily, 300/100 mg atazanavir/ritonavir once a day or 600 mg efavirenz once a day. The viral response was monitored at screening, baseline and at 1, 2, 3, 4, 12, 24, 48, 96, 120, and 144 weeks after study initiation. Data up to 400 days was fitted using a viral dynamics non-linear mixed effects drug-disease model in NONMEM. HIV-RNA data below LOQ of 50 copies/ml plasma (39%) was omitted, replaced by LOQ/2 or included in the analysis using a likelihood-based method (M3 method). Including data below LOQ using the M3 method substantially improved the model fit. The drug response parameter expressing the fractional inhibition of viral replication was on average (95% CI) estimated to 0.787 (0.721-0.864) for lopinavir and atazanavir treatment arms and 0.868 (0.796-0.923) for the efavirenz containing regimen. At 400 days after treatment initiation 90% (76-100) of the lopinavir and atazanavir treated patients were predicted to have undetectable viral levels and 96% (89-100%) for the efavirenz containing treatment. Including viral data below the LOQ rather than omitting or replacing data provides advantages such as better model predictions and less biased parameter estimates which are of importance when quantifying antiretroviral drug response.
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