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Switching to Unboosted Atazanavir Combined with Tenofovir and Emtricitabine Is Effective as Maintenance Therapy
  Reported by Jules Levin
Glasgow 2012


L. Skeie, & A. Maeland;
Oslo University Hospital, Ulleval, Norway
Background: Due to a pharmacokinetic interaction leading to reduced serum levels of atazanavir (ATV) when combined with tenofovir (TDF), it is recommended to add ritonavir (r) as a booster for atazanavir when combined with TDF. However, ATV is also licensed for use as an unboosted drug.
In our clinic many patients switched to unboosted ATV after viral suppression was achieved, mostly for simplification. We report on the virological efficacy of unboosted ATV with TDF and emtricitabine (FTC) in our clinic cohort.
File review of all patients with no history of virological failure switching to unboosted ATV (400 mg) +TDF+FTC with a HIV- 1-RNA of <400 copies/ml. Virological failure was defined as two consecutive HIV-1-RNA measurements > 400 copies/ml.
Results: 178 patients (pts) were observed for 1-81 (median 16.5, IQR 7-27) months totaling 325 patient years. Mean age at switch was 44 years, mean weight 76 kg, mean CD4 516 cells/mm3. Duration of preceding viral suppression was 0 - 177 (median 18, IQR 7-38) months. Most common preceding regimen was ATV/r+TDF+FTC (89 pts). Most common reasons given for switching to ATV+TDF+FTC were simplification (83 pts), dyslipidemia (17), gastrointestinal toxicity (10), coronary risk (10), CNS toxicity (10), hyperbilirubinemia (6).
No virological failure was observed. 113, 86 and 62 pts were observed for at least 12, 18 and 24 months; with CI95% for virological failure 0 - 2.6%, 0 - 3.4% and 0 - 4.7% respectively. Improvements in lipid and bilirubin values were seen after switching to ATV+TDF+FTC.
118 pts are still on the regimen. Most frequent reasons for switching from ATV+TDF+FTC to another regimen were: elevated creatinine (11 pts) viral load blips <200 kopier/ml (7) death - non-HIV related (5) pregnancy (4) pts' own decision (4) gastrointestinal intolerance (3). Of the 7 patients who switched to a new regimen due to viral load blips, 6 achieved viral load suppression following the switch and 1 patient with compliance problems did not.
Conclusion: Switching to unboosted ATV combined with TDF and FTC is effective as maintenance therapy in patients with viral load suppression and no prior treatment failure.

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