Association between ABCC2 gene haplotypes and tenofovir-induced proximal tubulopathy.
ABSTRACT Tenofovir disoproxil fumarate (TDF) may induce renal proximal tubulopathy (rPT). There are no data on pharmacogenomic predictors of rPT in the genes encoding the multidrug-resistance protein (MRP) 2 and MRP4 transporters.
Mutational screening of the genes for MRP2 (ABCC2) and MRP4 (ABCC4) was performed using genomic DNA from 13 human immunodeficiency virus type 1 (HIV-1)-infected patients (group 1) presenting with TDF-induced rPT. Concomitantly, 17 unrelated HIV-1-infected patients who had received TDF therapy and who did not have rPT (group 2) were included in a case-control analysis, to assess the influence of single-nucleotide polymorphisms (SNPs) identified in ABCC2 and ABCC4.
Six SNPs were identified in ABCC2. A significant allelic association between the 1249 G-->A SNP and TDF-induced rPT was observed (odds ratio, 6.11 [95% confidence interval, 1.19-31.15]; P<.02). ABCC2 haplotypes were significantly associated with the onset of TDF-induced rPT--CATC appeared to be a predisposing haplotype, as it was found in 40.9% of the group 1 case patients and in 13.7% of the group 2 control subjects (P<.01), whereas CGAC appeared to be a protective haplotype, as it was not observed in the group 1 case patients but was present in 20.2% of the group 2 control subjects (P<.01). No association was observed between ABCC4 polymorphism and TDF-induced rPT in the present study.
ABCC2 haplotypes are associated with rPT induced by TDF in HIV-1-infected patients.
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ABSTRACT: Many microorganisms, including viruses, some bacteria and fungi, replicate within the cells. Therefore, the efficacy of therapy and the selection of resistances could be related to intracellular concentration of the drugs and to their ability to cross biological membranes and penetrate into various tissue compartments. The efficacy of treatment may be limited by pharmacological factors. Dose-response relationship exists for many agents, and failure to maintain adequate concentrations may allow the development of viral or bacterial resistance, thereby decreasing the probability of response of current and subsequent therapies. The major target of antivirals and many other anti-infective agents is within infected cells. Therefore, clinical outcome ultimately should be related to intracellular drug concentrations. Intracellular pharmacokinetics provides information regarding drug disposition in a compartment where microorganism replication occurs and combined with plasma data may be useful in understanding therapeutic failure in relation to cellular resistance. With a focus on possible methodological biases, this review reports the current state of the art in intracellular, particularly in peripheral blood mononuclear cells, therapeutic drug monitoring of the following anti-infective drugs: antivirals, antifungals and antibiotics. Although measurement of intracellular concentrations needs to be still standardized focusing on each single drug, this review showed some relationships between intracellular concentrations of few anti-infective drugs and their efficacy and/or toxicity. Such relationships should be interpreted with caution, as intracellular concentrations reflect the total amount of drug within the cell and not the effective unbound fraction. The number of clinical studies in that area is, however, rather limited, and not always adequately designed. Then, intracellular drug determination has to be considered a test for research only and not to be carried out as routine.Journal of pharmaceutical and biomedical analysis 04/2014; · 2.45 Impact Factor
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ABSTRACT: To study the correlations of genetic variants of tenofovir tubular transporters, plasma tenofovir concentrations and clinical factors with decreased glomerular filtration rate in HIV-infected patients who received tenofovir. A total of 117 HIV-1-infected patients were administered antiretroviral therapy with tenofovir/lamivudine/efavirenz. Two single nucleotide polymorphisms (SNPs), ABCC2*1C c.-24C>T and ABCB1*6 c.3435C>T, were genotyped. At week 24, plasma tenofovir concentration at 12 h after drug intake was measured. Serum creatinine and estimated glomerular filtration rate (eGFR) calculated by the Modification of Diet in Renal Disease study formula were measured every 24 weeks until 96 weeks. Overall, mean ± SD age was 37 ± 9 years. Mean ± SD baseline eGFR was 130.3 ± 35.0 mL/min/1.73 m(2). The frequencies of wild-type/heterozygous/homozygous mutants of ABCC2*1C were 57%/39%/4% and those of ABCB1*6 were 28%/51%/21%. Mean ± SD plasma tenofovir concentration at 24 weeks was 105 ± 46 ng/mL. At week 48, m-ean ± SD eGFR of ABCC2*1C CC versus CT/TT was 96 versus 108 mL/min (P = 0.005) and m-ean ± SD eGFR of ABCB1*6 CC versus CT/TT was 106 versus 99 mL/min (P = 0.157). Mean ± SD tenofovir concentration in ABCC2*1C genotype CC versus CT/TT was 113 ± 47 versus 93 ± 44 ng/mL, respectively (P = 0.018). By multivariate analysis I, decreased eGFR at week 48 was correlated to ABCC2*1C genotype CC (P = 0.001), low eGFR at baseline (P = 0.006) and older age (P = 0.048). By multivariate analysis II, decreased eGFR at week 48 was correlated to high plasma tenofovir concentration (P = 0.001) and low eGFR at baseline (P = 0.019). HIV-infected patients who carry ABCC2*1C genotype CC at position -24 or have high plasma tenofovir concentration are at risk of decreased glomerular filtration rate.Journal of Antimicrobial Chemotherapy 04/2014; · 5.34 Impact Factor