Laura Trentini

The use of trough ribavirin concentration to predict sustained virological response and haematological toxicity in HIV/HCV-co-infected patients treated with ribavirin and pegylated interferon

OBJECTIVES To study the association between trough ribavirin concentration (C(trough)) with sustained virological response (SVR) and haemoglobin (Hb) decrease in HIV/hepatitis C virus (HCV)-co-infected (HIV+/HCV+) patients treated with anti-HCV therapy. METHODS HIV+/HCV+ patients treated with ribavirin and pegylated interferon were prospectively evaluated. Qualitative and quantitative HCV-RNA, Hb levels and ribavirin C(trough) were measured at baseline and weeks 2, 4, 12, 24, 36 and 48 during therapy. HCV-RNA was also measured at 24 weeks after the end of therapy. Efficacy analysis was performed on patients with a definitive virological outcome (SVR, relapser and non-responder), whereas for toxicity analysis, dropouts were considered until the last available observation. RESULTS Fifty-two patients (54.7% with genotype 1 or 4) were included. Overall, no correlation between ribavirin C(trough) and early virological response (EVR) nor SVR was found. However, in patients with genotype 1 or 4, ribavirin C(trough) was independently associated with EVR (P = 0.036) and SVR (P = 0.046). A ribavirin C(trough) cut-off of 1600 ng/mL was found to be associated with both EVR (chi(2) = 5.69, P = 0.028) and SVR (chi(2)=4.2, P = 0.04). Higher ribavirin C(trough) correlated with Hb decrease (R = -0.361, P = 0.009) and was independently associated with an Hb decrease of >4 g/dL (P = 0.009). Receiver operating characteristic (ROC) analysis indicated that a ribavirin C(trough) of >2300 ng/mL was associated with an Hb decrease of >4 g/dL (chi(2) = 8.08, P = 0.01). CONCLUSIONS Our study confirmed a relationship between ribavirin exposure and both efficacy and toxicity. Moreover, we found ribavirin C(trough) cut-offs for both SVR in genotypes 1 and 4 and overall haematological toxicity. These findings deserve further clinical evaluation.

Intracellular accumulation of atazanavir/ritonavir according to plasma concentrations and OATP1B1, ABCB1 and PXR genetic polymorphisms

OBJECTIVES The rate of accumulation of atazanavir and ritonavir within cells is still debated due to methodological limitations. Our aim was to measure peripheral blood mononuclear cell (PBMC) concentrations of atazanavir and ritonavir and investigate whether single-nucleotide polymorphisms of OATP, ABCB1, CYP3A4 and PXR genes are involved in intracellular drug penetration. METHODS HIV-positive patients administered 300 mg of atazanavir/100 mg of ritonavir were enrolled. Blood sampling was performed at the end of the dosing interval (Ctrough). PBMC-associated and plasma atazanavir and ritonavir concentrations were measured by validated HPLC coupled with a single mass detector (HPLC-MS) and HPLC-photodiode array (PDA) methods, respectively. Cell count and mean cellular volume were determined using a Coulter counter. Genotyping was conducted using real-time PCR. RESULTS Thirty-five patients were enrolled. Median atazanavir and ritonavir intracellular concentrations were 1844 and 716 ng/mL, respectively. Median plasma concentrations were 645 ng/mL for atazanavir and 75 ng/mL for ritonavir, while median intracellular/plasma concentration ratios were 2.4 and 9.2, respectively. Median ritonavir intracellular concentrations were higher for OATP1B1 521 T→C TC or CC carriers and for PXR 44477 A→G AG or GG carriers. Atazanavir intracellular/plasma concentration ratios were higher in patients GG for the ABCB1 2677 G→T single-nucleotide polymorphism (SNP) compared with GT and TT groups. CONCLUSIONS Our study showed a higher intracellular ritonavir accumulation than previously reported. Ritonavir intracellular concentrations were associated with OATP1B1 521 and PXR 44477 SNPs while intracellular atazanavir exposure was associated with the ABCB1 2677 SNP. Further clinical studies are necessary in order to confirm these data.

Blackwater fever in children, Burundi.

Blackwater fever is characterized by acute intravascular hemolysis with hemoglobinuria in patients with Plasmodium falciparum malaria. Its pathogenesis and management are still debated. Nine cases of this syndrome occurred in 2003 at Kiremba Hospital in Burundi in children receiving multiple quinine treatments.

Intracellular accumulation of ritonavir combined with different protease inhibitors and correlations between concentrations in plasma and peripheral blood mononuclear cells

OBJECTIVES Ritonavir, used at low doses as a boosting agent of other protease inhibitors (PIs), is known to be associated with metabolic complications and gastrointestinal disturbances. The rate of accumulation of ritonavir within cells is still debated due to scarce data and methodological limitations. Therefore, our aim was to evaluate intracellular ritonavir penetration when used with different boosted PIs in the clinical setting. METHODS Patients administered with atazanavir/ritonavir (300/100 mg, once daily), darunavir/ritonavir [600/100 mg, twice daily (darunavir-600) and 800/100 mg, once daily (darunavir-800)], lopinavir/ritonavir (400/100 mg, twice daily) and tipranavir/ritonavir (500/200 mg, twice daily) were considered. Blood sampling at the end of the dosing interval (Ctrough) was performed. Peripheral blood mononuclear cell (PBMC)-associated and plasma ritonavir and PI concentrations were measured by validated HPLC methods. PBMC count and individual mean cell volume (MCV) were measured using a Coulter Counter instrument. RESULTS One hundred patients were enrolled. Frequencies of ritonavir-boosted PIs were atazanavir, 37%; darunavir-600, 23%; lopinavir, 19%; tipranavir, 13%; and darunavir-800, 8%. The median intracellular and plasma concentrations of ritonavir were 1279 ng/mL (IQR 727-2087) and 170 ng/mL (IQR 82-384), respectively, accounting for a cellular accumulation ratio of 7.69 (5.7-10.9). Significant differences in ritonavir intracellular concentrations emerged among different PIs (P<0.001): specifically between darunavir-600 and atazanavir (P<0.001), between darunavir-600 and tipranavir (P=0.009), between atazanavir and lopinavir (P<0.001) and between lopinavir and tipranavir (P=0.027). CONCLUSIONS Our study showed a higher rate of ritonavir intracellular accumulation than previously reported, possibly due to the more accurate calculation of intracellular concentrations by MCV. The ratio varied according to concomitantly administered PIs, suggesting their influence on the rate of ritonavir intracellular penetration.

Tipranavir (TPV) Genotypic Inhibitory Quotient Predicts Virological Response at 48 Weeks to TPV-Based Salvage Regimens

ABSTRACT The virological response (VR) to a tipranavir-ritonavir (TPV-RTV)-based regimen had been shown to be associated with a number of mutations in the protease gene, the use of enfuvirtide (T20), and the TPV phenotypic inhibitory quotient (IQ). The role of the TPV genotypic IQ (gIQ) has not yet been fully investigated. The aim of our study was to evaluate the relationship between the TPV gIQ and the VR at 48 weeks to TPV-based salvage regimens. Patients placed on regimens containing two nucleoside reverse transcriptase inhibitors plus TPV-RTV 500/200 mg twice a day with or without T20 were prospectively studied. Regular follow-up was performed over the study period. VR, considered a viral load (VL) decrease of ≥1 log unit and/or the achievement of <50 copies/ml with no VL rebound of >0.5 log unit compared to the maximal VL decrease at week 48, was assessed. Thirty-eight patients who had received multiple drugs were included. At week 48 the VL decrease was −1.48 (interquartile range [IQR], −2.88 to −0.48), 15 patients (39.5%) had VLs of <50 copies/ml, and the CD4+ cell count increase was 37 cells/mm3 (IQR, −30 to +175). Twenty subjects (52.6%) achieved VRs. The TPV gIQ and optimized background score (OBS) were independently associated with higher VL decreases. The TPV gIQ and OBS were also independent predictors of a VR at week 48. TPV gIQ and OBS cutoff values of 14,500 and 2, respectively, were associated with a higher rate of VR. The TPV gIQ was shown to be able to predict the VR at 48 weeks to TPV-containing salvage regimens better than the TPV trough concentration or TPV-associated mutations alone. A possible TPV gIQ cutoff value of 14,500 for reaching a VR at week 48 was suggested. Further studies are needed in order to evaluate the calculation of TPV gIQ as a new tool for the optimization of TPV-based salvage therapy.

Moxifloxacin for the treatment of HIV-associated tuberculosis in patients with contraindications or intolerance to rifamycins

Administration of rifampicin or rifabutin in the treatment of HIV-associated tuberculosis (TB) is made rather complex by the risk of drug-drug interactions with most antiretrovirals and/or for reasons of toxicity. While in selecting the appropriate concomitant regimens the priority usually goes to rifamycins with exclusion of interacting antiretrovirals, in some circumstances the former cannot be used and anti-TB rifamycin-free regimens must be administered. We describe here the clinical course of two patients with HIV-associated TB in whom the last generation fluorquinolone moxifloxacin (found to exert significant activity against Mycobacterium tuberculosis) successfully replaced rifamycins.

Clinical pharmacology of tenofovir clearance: a pharmacokinetic/pharmacogenetic study on plasma and urines

The HIV virus and hepatitis B virus nucleotide reverse transcriptase inhibitor tenofovir has been associated with proximal tubular toxicity; the latter was found to be predicted by plasma concentrations and with single-nucleotide polymorphisms in transporters-encoding genes. A cross-sectional analysis in adult HIV-positive patients with estimated creatinine clearance >60 ml min−1 was performed. Twelve-hour plasma and urinary tenofovir concentrations and single-nucleotide polymorphisms in several transporter-encoding genes were analysed. In 289 patients 12-h tenofovir plasma, urinary and urinary to plasma ratios were 69 ng ml−1 (interquartile range 51.5–95), 24.3 mg ml−1 (14.3–37.7) and 384 (209–560). At multivariate analysis estimated creatinine clearance, protease inhibitors co-administration and SLC28A2 CT/TT genotypes were independently associated with plasma tenofovir exposure; ABCC10 GA/AA genotypes and protease inhibitor co-administration were independently associated with the urinary to plasma tenofovir ratio. Tenofovir clearance was associated with genetic polymorphisms in host genes and with co-administered drugs: if confirmed by ongoing studies these data may inform treatment tailoring and/or dose reductions.

Pharmacokinetics of switching unboosted atazanavir coadministered with tenofovir disoproxil fumarate from 400 mg once daily to 200 mg twice daily in HIV-positive patients.

BACKGROUND Use of unboosted atazanavir (ATV) with tenofovir disoproxil fumarate (TDF), although attractive from a clinical view point, has not been tested in trials and is not currently recommended because of the risk of suboptimal ATV pharmacokinetics (PK). In order to improve ATV exposure, plasma and intracellular (IC) PK of ATV in patients administered with ATV 400 mg once daily and TDF/emtricitabine (FTC) and switched to ATV 200 mg twice daily were studied. METHODS On day 0, 10 subjects on ATV 400 mg plus TDF/FTC once daily underwent intensive plasma and IC PK evaluation and bilirubin measurement. Patients were subsequently switched to ATV 200 mg twice daily for 10 days. On day 11, they once again underwent intensive PK and bilirubin evaluation. RESULTS Switch to 200 mg twice daily led (in plasma) to a significant increase of the observed concentration at the end of dosing interval (C(trough); ratio twice daily/once daily 2.20; P=0.005), with a decrease from 60% to 20% of suboptimal values, a significant decrease of the maximum concentration (C(max); ratio twice daily/once daily 0.47; P=0.022), whereas no differences of other PK parameters or bilirubin were observed. IC ATV concentrations at 400 once daily showed higher C(trough) (ratio peripheral blood mononuclear cells [PBMCs]/plasma 2.86; P=0.005) and longer half-life (ratio PBMCs/plasma 1.44; P=0.007) as compared with plasma. After the switch, IC ATV accumulation showed changes similar to plasma. CONCLUSIONS Switch to 200 mg twice daily appeared to optimize plasma and IC ATV PK, by increasing the determinant of efficacy (C(trough)) and decreasing C(max), without significant effect on total ATV plasma exposure and bilirubin. Dosage of 200 mg might provide an option to patients showing suboptimal ATV exposure with standard unboosted dosing.

Transplacental passage of etravirine and maraviroc in a multidrug-experienced HIV-infected woman failing on darunavir-based HAART in late pregnancy

Sir, Although highly active antiretroviral treatment (HAART) in HIV-infected pregnant women has been shown to be effective in reducing mother-to-child-transmission (MTCT), some therapeutic issues remain a concern. Changes in drug pharmacokinetics (PK) in the second and third trimesters could cause reductions in plasma exposure of several antiretrovirals, while for most recent compounds few data are available. Boosted darunavir is widely used in multidrug-experienced pregnant patients, but information in this setting is limited to heterogeneous case reports showing lower trough concentrations (1168–1908 ng/mL) as compared with non-pregnant patients. – 6 The use of inhibitory quotients (IQs) has been proposed to individualize the exposure of drugs in relation to the harboured viruses: our group showed that the darunavir weighted score genotypic IQ (ws gIQ) was the most accurate predictor of virological response in treatmentexperienced patients. Therefore the use of darunavir ws gIQ could help clinicians to manage multidrug-experienced pregnant women. We describe the case of a young woman infected with HIV and hepatitis C virus whose therapeutic history includes suboptimal adherence to several antiretrovirals and virological failures on regimens containing efavirenz, indinavir and saquinavir. HIV polymerase revealed resistance-associated mutations both in the reverse transcriptase (D67N, T69N, K70R, A98G, M184V, K103N and K219Q) and the protease (M46I, I84V and L90M) gene. After successfully receiving tenofovir/emtricitabine and darunavir/ritonavir (800/100 mg once daily) she discontinued every treatment. Two years later she agreed to reinitiate tenofovir/emtricitabine and once-daily darunavir/ritonavir: at this time she presented with 539 CD4+ T lymphocytes/mm (15%, 0.27 CD8/CD4 ratio), 55500 HIV RNA copies/mL and an R5 tropic virus. Three months later (at 10 weeks of gestational age) her pregnancy test was positive and her darunavir/ritonavir dosage was increased to 600/100 mg twice daily. After a net decrease in viral load (252 copies/mL at 16 weeks and 115 copies/mL at

Pharmacokinetic and pharmacodynamic determinants of early virological response to enfuvirtide-based regimens in HIV-positive patients

BACKGROUND Early virological response (VR) to enfuvirtide-based salvage regimens at week 12 has been described as a predictor of long-term therapeutic success. The relationship between enfuvirtide plasma exposure and VR has not yet been investigated in the clinical setting. Our aim was to investigate the role of enfuvirtide plasma exposure as a determinant of early VR in the clinical setting. METHODS Forty-two multidrug-experienced patients starting a salvage enfuvirtide-based regimen were prospectively evaluated over a 12 week period. HIV-RNA levels and enfuvirtide C(trough) were regularly measured. VR was considered as achievement of viral load (VL) undetectability and/or a decrease of more than 1 log at week 12. RESULTS Optimized background score (OBS) and enfuvirtide C(trough) concentrations were associated with VL decrease at week 12. An OBS > or =2 and enfuvirtide C(trough) >2100 ng/mL were associated with VR. The pharmacokinetic/pharmacodynamic (PK/PD) analysis confirmed this exposure-response relationship both in the total population and in different groups according to OBS <2 or > or =2. Higher estimates of IC(50) were calculated for the OBS <2 group when compared with the OBS > or =2 group (7551 versus 2330 ng/mL, respectively), without a marked difference in I(0) (0.31 versus 0.21 log) and I(max) (-2.64 versus -3.33 log). CONCLUSIONS Enfuvirtide plasma exposure and OBS were found to significantly influence the magnitude and rate of early VR. The PK/PD modelling of enfuvirtide concentrations was different in our clinical setting, compared with previous data obtained under trial conditions. Therefore, optimization of enfuvirtide plasma exposure could deserve further evaluation as a determinant of therapeutic response in HIV-positive patients.