The Association of Tacrolimus Formulation Switching with Trough Concentration Variability: A Retrospective Cohort Study of Tacrolimus Use Post-Kidney Transplantation Based on National Drug Code (NDC) Numbers.

INTRODUCTION: It was hypothesized that patients experiencing at least one tacrolimus formulation switch may require more frequent therapeutic drug monitoring, subsequent dose adjustments, and a potential for untoward clinical outcomes than patients who remain on a single formulation. METHODS: Eligible patients were adult kidney transplant recipients with stable renal function at month 3 post-transplant and no evidence of acute rejection, receiving an oral, tacrolimus-based regimen. Patients were categorized into two groups (fixed or variable formulation) using the US National Drug Code (NDC) on the basis of tacrolimus formulation usage over the 12-month period. RESULTS: A total of 305 patients were enrolled from four US transplant centers; 44 (14.4%) received multiple formulations and 261 (85.6%) received a single formulation. Mean number of tacrolimus dose adjustments and mean cumulative milligram dose change were not statistically different between the two groups. Mean trough-to-dose ratio, frequency of trough level measurements, and mean number of excursions above 120% or below 80% of the patient's mean trough concentration were significantly higher in the variable compared to the fixed formulation group. CONCLUSION: A variable tacrolimus formulation regimen was associated with a higher frequency of trough level measurements and a greater number of excursions in trough levels compared with continuing on a fixed formulation regimen of tacrolimus in this retrospective chart review study. FUNDING: Astellas Pharma Global Development, Inc. Plain language summary available for this article.

Healthcare utilization and costs with fixed-source versus variable-source tacrolimus in patients receiving a kidney transplant.

AIMS: Switching drug manufacturers in transplant patients may require an increased intensity of therapeutic monitoring, leading to additional healthcare visits, associated laboratory tests, and perhaps hospitalizations. As real-world studies examining the interchangeability of tacrolimus from different manufacturers are limited, the purpose of this study was to examine the healthcare resource utilization (HRU) and economic impact of tacrolimus-switching in kidney transplantation. MATERIALS AND METHODS: This cross-sectional, retrospective study examined HRU and healthcare costs (HCCs) among patients with a kidney transplant who were prescribed tacrolimus from fixed-source (FS) vs variable-source (VS) manufacturers using claims data from the large US health plan Humana from October 1, 2012, to December 31, 2013. RESULTS: Overall, 1,024 patients were identified (FS: n = 674, 66%; VS: n = 350, 34%). The number of therapeutic drug monitoring (TDM) events for the VS group was 13% greater than for the FS group after controlling for demographics, comorbidity score, and number of medications (incidence rate ratio = 1.13, p = .033). Adjusted total HCCs were 9% lower for VS (US$28,054 vs US$30,823, p = .045). In the unadjusted analysis, VS had greater emergency department (ED) utilization (45% vs 35%, p < .002). In the VS group, the mean (standard deviation [SD]) number of days from manufacturer switch to first outpatient visit was 23.8 (33.6), and the number of days (SD) to first TDM event was 43.6 (56.2). LIMITATIONS: Study limitations include the lack of availability of many transplant-specific variables within the Humana database, potential errors/omissions in claims coding, and restriction of cross-sectional data examination to a 1-year period. CONCLUSIONS: VS patients had greater TDM and lower total HCCs. Further research is warranted to understand the drivers of ED use among the VS group, and to determine factors associated with delayed TDM after regimen modification. Opportunities may exist to improve the quality of care for patients receiving immunosuppressant treatment with tacrolimus.

Regimen simplification to atazanavir-ritonavir alone as maintenance antiretroviral therapy: final 48-week clinical and virologic outcomes.

BACKGROUND: Simplified maintenance therapy with ritonavir-boosted atazanavir (ATV/RTV) alone is attractive because of nucleoside reverse-transcriptase inhibitor (NRTI)-sparing benefits, low pill burden, once-daily dosage, and safety. METHODS: Subjects with virologic suppression after > or = 48 weeks of initial antiretroviral therapy with 2 NRTIs and a protease inhibitor (PI) were enrolled. Subjects switched to ATV/RTV at entry and discontinued NRTIs after 6 weeks. The primary end point was time to virologic failure (confirmed HIV-1 RNA level > or = 200 copies/mL). Drug resistance at virologic failure was evaluated by standard genotyping and single-genome sequencing (SGS). Residual viremia (1.1-49 copies/mL) was measured by single-copy assay. RESULTS: Thirty-four subjects simplified to ATV/RTV alone, of whom 30 (88%) did not experience virologic failure by 48 weeks after simplification. Residual viremia did not change significantly after NRTI discontinuation among those without virologic failure but did increase 4-12 weeks before confirmed virologic failure. No major PI-resistance mutations were identified at virologic failure by standard genotyping or SGS. CONCLUSIONS: In this pilot study, simplified maintenance therapy with ATV/RTV alone maintained viral suppression in most subjects through 48 weeks. PI resistance was not detected among subjects experiencing virologic failure. Larger, randomized trials are warranted to further define the efficacy and safety of this strategy.

Maintaining reduced viral fitness and CD4 response in HIV-infected patients with viremia receiving a boosted protease inhibitor.

When fully suppressive regimens are not available, incompletely suppressive regimens also provide immunologic benefits. In this study, with stable background therapy, human immunodeficiency virus (HIV)-infected patients who were randomized to receive atazanavir or boosted atazanavir, compared with those who continued boosted protease inhibitor therapy, maintained similar virologic and immunologic control, resistance-mutation patterns, and replication capacities with reduced use of lipid-lowering medication.

Regimen simplification to atazanavir-ritonavir alone as maintenance antiretroviral therapy after sustained virologic suppression.

CONTEXT: The long-term adverse effects, expense, and difficulty of adherence to antiretroviral regimens have led to studies of simpler maintenance therapies. Maintenance therapy with ritonavir-boosted atazanavir alone is a possible option because of low pill burden, once-daily dosing, safety, and unique resistance profile. OBJECTIVE: To assess whether simplified maintenance therapy with atazanavir-ritonavir alone after virologic suppression increases the risk of virologic failure (2 consecutive human immunodeficiency virus type 1 [HIV-1] RNA measurements of > or =200 copies/mL). DESIGN, SETTING, AND PARTICIPANTS: Single-group, open-label, multicenter, 24-week pilot study of 36 HIV-infected adults with virologic suppression for 48 weeks or longer receiving their first protease inhibitor (PI)-based regimen. The study was conducted between September 1, 2004, and April 18, 2006, at 12 participating AIDS clinical trial units in the United States. INTERVENTION: Participants switched PIs to atazanavir-ritonavir at entry and discontinued nucleoside analog reverse transcriptase inhibitors (NRTIs) after 6 weeks. MAIN OUTCOME MEASURES: Virologic failure within 24 weeks of discontinuing NRTIs. Other measures included HIV-1 drug resistance, plasma atazanavir concentrations, adverse events, CD4 cell counts, plasma lipid levels, and HIV-1 RNA levels in seminal plasma. RESULTS: Thirty-six participants enrolled and 2 discontinued before simplification to atazanavir-ritonavir alone. Thirty-four patients were included in the analysis of the primary end point after 24 weeks: 1 withdrew voluntarily, and 33 continued the regimen. Virologic success (absence of failure) through 24 weeks of simplified therapy occurred in 91% (31 of 34 patients; lower 90% confidence interval limit = 85%). Three participants experienced virologic failure 12, 14, and 20 weeks after simplification, with plasma HIV-1 RNA levels of 4730, 1285, and 28 397 copies/mL, respectively. Resistance testing at failure did not identify PI resistance mutations. Plasma atazanavir concentrations at failure were low or below detection in 2 of 3 participants experiencing failure. There were no treatment discontinuations for adverse events after simplification; no significant changes in CD4 cell counts or plasma lipid levels; and no detectable HIV-1 RNA in seminal plasma from all 8 participants tested. CONCLUSIONS: These preliminary data suggest that simplified maintenance therapy with atazanavir-ritonavir alone may be efficacious for maintaining virologic suppression in carefully selected patients with HIV infection. These findings require confirmation in larger, randomized trials of this strategy. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00084019.