3rd International AIDS Society Conference on HIV Pathogenesis and Treatment Rio de Janeiro - July 24 - 27, 2005

VARIABILITY OF ATAZANAVIR PLASMA CONCENTRATIONS IN HIV-INFECTED PATIENTS: RESULTS OF A PROSPECTIVE FRENCH COHORT

IAS Conf HIV Pathog Treat 2005 Jul 24-27;3rd: Abstract No. WePe3.2C13

Guiard-Schmid J.-B.¹, Poirier J.-M.², Bonnard P.¹, Meynard J.-L.³, Lukiana T.1, Slama L.¹, Rozenbaum W.¹, Jaillon P.², Pialoux G.^1
1Service des Maladies Infectieuses et Tropicales, Hôpital Tenon, AP-HP, Université Pierre et Marie Curie Paris VI, Paris, France, ²Service de Pharmacologie Clinique, UFR Saint Antoine, Université Pierre et Marie Curie, Paris, France, ³Service des Maladies Infectieuses et Tropicales, Hôpital Saint-Antoine, AP-HP, Université Pierre et Marie Curie Paris VI, Paris, France

INTRODUCTION: Little is known about ATV plasma concentrations in the "real life" of clinical practice, especially inter/intraindividual variability and drug interactions.

METHODS: We prospectively measured trough ATV (C_min) plasma concentrations in HIV-infected patients treated with different ATV regimens and assessed the role of non nucleosidic reverse transcriptase inhibitors (NNRTI) on ATV C_min. Plasma ATV C_min were determined by High-Pressure-Liquid-Chromatography, 24 hours (± 4) after last drug dose intake.

RESULTS: 70 patients were included. 21 of them were receiving ATV 400 mg without ritonavir (RTV), 37 RTV boosted ATV regimen 300/100 mg, with NNRTI in 5 pts and 7 were receiving 400/100 mg ATV boosted regimen with NNRTI. The ATV C_min intra-individual variability was assessed in 14 patients.

Median ATV C_min were 151 [34-1159] and 494 [147-1731] ng/ml in patients receiving non boosted 400 mg and boosted 300/100 mg regimens respectively, a 3.3 fold increase in ATV C_min in boosted versus unboosted regimens (p<0.0001). ATV C_min inter-individual variability was majored in unboosted regimen (coefficient of variation of 118% versus 73% with RTV). For intraindividual variability, median ATV C_min coefficient of variation were 44% in 6 patients and 40% in 8 patients receiving non boosted 400 mg and boosted 300/100 mg regimens respectively. NNRTIs were found to significantly decrease ATV C_min in patients receiving boosted 300/100 mg ATV regimen (n=5, p<0.0005) when boosted ATV 400/100 mg regimen (n=8) showed C_min comparable to 300/100 mg ATV regimen without NNRTIs.

CONCLUSIONS: Correlation between plasma concentration and virological efficacy of ATV is not clarified yet. But marked inter and intraindividual ATV C_min variability should lead to individual therapeutic drug monitoring assessment. If NNRTI is combined with ATV, only RTV boosted 400/100 mg ATV regimen can overcome NNRTI's inducer effect.

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050724
Clinical | WePe3.2C13 | Jean-Baptiste Guiard-Schmid
Pharmacological monitoring of ARV therapy

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