L. Marinaro

Determinants of darunavir cerebrospinal fluid concentrations: impact of once-daily dosing and pharmacogenetics.

Objectives:To compare cerebrospinal fluid (CSF) darunavir and ritonavir concentrations in patients receiving darunavir/ritonavir 800/100 mg once daily or 600/100 mg twice daily. To determine the influence of single-nucleotide polymorphisms in the genes encoding for blood–brain barrier transporters (ABCB1 3435 C>T, ABCB1 1236 C>T, ABCB1 2677 G>T, SLCO1A2 38 A>G, SLCO1A2 516 A>C, ABCC2 -24 G>A) on darunavir and ritonavir penetration into CSF. Design:Comparative pharmacokinetics study in patients. Methods:Plasma and CSF darunavir and ritonavir concentrations (2–26 h after drug intake) were determined by a validated HPLC coupled with mass spectrometry method in adults on darunavir-based combination antiretroviral therapy undergoing a lumbar puncture. Results:HIV-infected patients on once-daily darunavir/ritonavir had significantly lower CSF darunavir trough concentrations and CSF-to-plasma ratios than patients on darunavir/ritonavir twice-daily (10.7 versus 38.2 ng/ml and 0.32 versus 0.90%; P < 0.05). No significant effect of single-nucleotide polymorphisms in the genes encoding for blood–brain barrier transporters was noted apart from slightly higher CSF darunavir penetration in patients carrying OATP1A2 uncommon variants. Conclusions:This is the first study to compare darunavir CSF concentrations in patients taking the once-daily or the twice-daily dosage: our data show that darunavir and ritonavir dosing significantly affects not only CSF concentrations but also the extent of drug penetration into the CSF. Furthermore a minority of patients in the once-daily arm presented very low CSF concentration of potential concern for HIV control in the central nervous system. The relative importance of pharmacogenetics in influencing CSF darunavir pharmacokinetics deserves further clinical investigation.

Cerebrospinal Fluid Inhibitory Quotients of Antiretroviral Drugs in HIV-Infected Patients Are Associated With Compartmental Viral Control

BACKGROUND Despite the efficacy of highly active antiretroviral treatment (HAART), a large proportion of human immunodeficiency virus (HIV)-infected patients may develop moderate neurocognitive impairment. Antiretroviral drug passage into the central nervous system may be relevant for preventing and treating HIV-associated neurocognitive disorder; nevertheless, clear cerebrospinal fluid (CSF) pharmacodynamic targets are not known. METHODS HAART-treated adults with wild-type HIV were prospectively enrolled. CSF concentrations (measured by mass spectrophotometric methods) and inhibitory quotients (CSF concentrations divided by in vitro 50% and 95% inhibitory concentrations) were compared among different drugs and related to CSF HIV RNA levels. CSF escape was defined as CSF HIV RNA >50 copies/mL despite contemporary plasma HIV RNA below that threshold. RESULTS One hundred twenty-seven patients (91 male [71.7%], 93 white [73.2%], with a median age of 46 years [interquartile range, 40.5-54.5 years]) provided 174 paired CSF and plasma samples. Twice-daily darunavir, once-daily darunavir, and efavirenz had the highest CSF 95% inhibitory quotients (18.5, 8.2, and 6.4, respectively). Higher nadir CD4 cell count (P = .01) and plasma HIV RNA <50 copies/mL (P < .001) were independent predictors of controlled CSF HIV RNA. Optimal drug exposure (CSF detectable drugs and 95% inhibitory quotient >1) was protective for CSF escape (P = .01). CONCLUSIONS Cerebrospinal fluid 95% inhibitory quotients may be used to compare antiretroviral drug compartmental exposure; they deserve longitudinal studies to assess the adequacy of CSF drug concentrations in treated HIV-infected patients.

Efavirenz pharmacogenetics in a cohort of Italian patients

The pharmacogenetics and pharmacokinetics of efavirenz (EFV) have been widely studied, although data in the Italian population are limited. Single nucleotide polymorphisms (SNPs) in the CYP2B6 gene have been associated with increased EFV plasma concentrations and central nervous system toxicity. The aim of this work was to evaluate EFV plasma exposure according to SNPs in genes involved in drug metabolism and elimination in a cohort of Italian HIV-1-positive patients treated with EFV. Plasma samples were used to measure EFV concentrations at 12h after intake (C12) by a validated HPLC/PDA system. Whole blood was used to identify SNPs in ABCB1, MRP2, CYP2B6, CYP2A6, UGT2B7, NR1I2 (PXR), NR1I3 (CAR) and HNF4α by real-time PCR. The association between SNPs and EFV plasma levels was evaluated through non-parametric tests. Among 201 patients, the median EFV C12 was 2618.5ng/mL. No significant associations were found for MRP2, CYP2A6, UGT2B7, PXR and CAR SNPs; conversely, an association of CYP2B6 516G>T, ABCB1 3435C>T and 2677G>T, and HNF4α 975C>G polymorphisms with EFV C12 was observed. In multivariate analysis, only CYP2B6 516 TT and ABCB1 3435 TT genotypes were independently associated with an EFV C12 of >4000ng/mL (toxicity cut-off). This study confirmed the role of CYP2B6 and ABCB1 polymorphisms, showed a relationship with HNF4α, and the lack of association of CYP2A6, UGT2B7, NR1I2 and NR1I3 SNPs on EFV plasma exposure. Data regarding some of the studied SNPs are the first obtained in an Italian cohort of HIV patients and lead to a global vision about EFV pharmacogenetics.

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.

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

Tenofovir clearance is reduced in HIV-positive patients with subclinical tubular impairment.

Objective:To assess if tenofovir (TFV) clearance is associated with urinary retinal-binding protein (RBP) in HIV-positive patients with normal estimated filtration rate. Design:A cross-sectional diagnostic study. Methods:HIV-positive patients with estimated creatinine clearance above 60 ml/min, on tenofovir disoproxil fumarate (TDF)-containing combination since at least 6 months, taking TDF at night, and without significant comorbidities (diabetes, untreated hypertension, known renal malformations, recurrent nephrolithiasis) and nephrotoxic drugs were included. TFV plasma and urinary concentrations were measured 12 h after drug intake (C12). RBP was measured through enzyme immunoassay kit on spot urines and corrected per urinary creatinine (uRBP/uCr); normality ranges were below 130 &mgr;g/g (in patients aged <50 years) and below 172 &mgr;g/g (in patients aged ≥50 years). Results:Two hundred and eighty-nine patients were included (median age of 45.8 years, 71.6% male and 85.4% whites); patients were concomitantly treated with nonnucleoside reverse transcriptase inhibitors (155, 53.6%), protease inhibitors (118, 40.8%), or integrase inhibitors (16, 5.5%)-containing regimens. Estimated creatinine clearance was 89.4 ml/min (78.6–105.9). Urinary RBP (uRBP) and uRBP/uCr were 204.6 ng/ml (92–380) and 169.7 &mgr;g/g (85.8–318.3), respectively; abnormally high uRBP/uCr was observed in 157 patients (54.3%). A multivariate binary logistic regression confirmed that both ethnicity (P = 0.004, &bgr; 2.93, 95% confidence interval 1.41–6.10) and TFV urinary C12 less than 21 mg/ml (P = 0.006, &bgr; 2.04, 95% confidence interval 1.12–3.41) were significantly associated with abnormal uRBP/uCr. Conclusion:HIV-positive TDF-treated patients showed a high prevalence of proximal tubular impairment: ethnicity (whites) and low urinary TFV concentrations were significantly associated with elevated uRBP. SDC video:http://links.lww.com/QAD/A852.

Raltegravir Plus Nevirapine as Maintenance Antiretroviral Therapy in HIV-Positive Patients: Safety, Efficacy and Pharmacokinetics

BACKGROUND Tolerability, long-term toxicities and selection of resistant variants limit the use and efficacy of antiretroviral drugs in HIV-positive patients. Novel combinations are needed for mantaining long-term control of HIV replication; nevertheless scarse data are available on protease inhibitor-free dual antiretroviral therapies. METHODS A multi-centric retrospective study was conducted including HIV-1-positive patients on raltegravir/nevirapine dual regimens. Plasma concentrations were measured as therapeutic drug monitoring while a subset of patients underwent intensive 12-hour pharmacokinetic evaluation. RESULTS A total of 77 patients switching from successful regimens (76.6% male, median age 52 years) was included; 10 patients on raltegravir plus nevirapine once-daily while 67 subjects on twice-daily schedule. After a median follow-up of 32 months 69 patients (89.6%) were still successfully on treatment. Three patients discontinued for side effects (skin rash or hepatoxicity). Virological failure was observed in five patients (6.5%, 3 on once-daily schedule): in 4 patients (80%) resistance-associated mutations were observed (4 reverse transcriptase, 2 integrase). Triglycerides decreased in patients switching with lipid abnormalities (n=52) and estimated creatinine clearance increased in those with less than 60 ml/min (n=13). Median trough raltegravir and nevirapine concentrations were 83 ng/ml (32-227) and 5460 ng/ml (4037-7221); intensive 12-hours pharmacokinetic parameters (n=7) were similar to published data. CONCLUSION Dual therapy with raltegravir/nevirapine in selected patients was highly effective over a 32-month follow up: virological failure was infrequent (6.5%), most common with once-daily schedule (60%) and often associated with the selection of resistance-associated mutations (80%). Twice-daily raltegravir plus nevirapine deserves further clinical evaluation as an NRTI- and PI-sparing strategy in selected patients.

Efficacy, Tolerability and Virological Consequences of Long-Term Use of Unboosted Atazanavir Plus 2 NRTIs in HIV-Infected Patients

PURPOSE Switch to unboosted atazanavir (ATV) is an attractive option due to convenience and tolerability in HIV-positive patients. With limited available data we investigated the determinants of long-term efficacy and the consequences of virological failure of unboosted atazanavir-based regimens. METHODS Retrospective analysis in two Italian large outpatient clinics including demographic, immunovirological, resistance and pharmacokinetic data. RESULTS 249 patients receiving atazanavir (400 mg once-daily) plus 2 NRTIs were included; 163 were males (65.5%) and median age was 47 years (42-51.5). Median CD4+ T-cell count was 396/uL (261-583); 146 (58.6%) presented a viral load < 50 copies/mL. Over a median follow up of 157 weeks (106-203) 193 patients (77.5%) were still on treatment with 10 (4%) and 2 (0.8%) stopping for virological failure or toxicity, respectively. Ten patients with virological failure presented newly selected resistance associated mutations (RAMs) for NRTIs (2/10) or ATV (4/10, one I50L). Total cholesterol and triglycerides showed significant decreases at 48 [-4 mg/dL and -41 mg/dL] and 96 weeks [-14 mg/dL and -54 mg/dL] as compared to baseline. At multivariate analysis a genotypic sensitivity score ≤ 1, atazanavir RAMs > 1 and suboptimal adherence were independently associated with virological failure; in lamivudine/emtricitabine-treated patients the presence of M184V (without other NRTI RAMs) was not associated with virological failure. CONCLUSION Unboosted-atazanavir containing regimens were efficacious (with uncommon virological failures) and well-tolerated (with improvements in lipid profile over time) treatments in HIV-positive patients. Isolated M184V in lamivudine/emtricitabine recipients was not associated with higher failure rates supporting the use of functional ATV-based dual therapies as maintenance strategies.

HIV-1 Very Low Level Viremia is Associated with Virological Failure in HAART-treated Patients

Abstract The aim of this study was to evaluate the impact of HIV-1 very low-level viremia (<50 copies/ml) on the 2-year risk of virological failure. A retrospective analysis including HIV-positive patients presenting two consecutive HIV RNA below 50 copies/ml (outpatient clinic in Italy, first semester of 2010) was performed. HIV RNA was measured through real time polymerase chain reaction (PCR) assay CAP/CTM HIV-1 version 2.0 (detection limit: 20 copies/ml) and stratified as undetectable RNA (“Target Not Detected”, TND), <20 copies/ml, 20–50 copies/ml. After 96 weeks virological failure was defined as two consecutive viral loads above 50 copies/ml. Log-rank tests and a multivariate Cox proportional hazard model were used for univariate and multivariate analysis. A total of 1,055 patients (71.4% male, 87.4% white, aged 46.7 years) were included: nadir and current CD4 cell counts were 203 cells/mm3 (106–292) and 554 cells/mm3 (413–713.5). HIV RNA was undetectable in 781 patients (74%), <20 copies/ml in 190...

Therapeutic drug monitoring of boosted PIs in HIV-positive patients: undetectable plasma concentrations and risk of virological failure

Background Therapeutic drug monitoring (TDM) of antiretroviral drugs is performed in selected HIV-positive patients. The aim of this study was to estimate the prevalence of undetectable plasma concentrations of ritonavir and boosted PIs and to evaluate the association between those and the 48 week risk of virological failure. Methods A TDM registry study and a retrospective follow-up study were conducted. Plasma concentrations were measured through validated methods. According to PI and ritonavir concentrations, patients were stratified as adherent, partially non-adherent or non-adherent. Virological outcome was evaluated 48 weeks afterwards. Results The TDM registry study included 2468 samples collected from 723 patients (68.1% male, median age 43.5 years). Eighty-seven samples (3.5%, 74 patients) and 68 samples (2.8%, 52 patients) were in the partially non-adherent and non-adherent groups, respectively; more patients on atazanavir/ritonavir (7.9%) versus darunavir/ritonavir (2% twice daily and 1.9% once daily) and lopinavir/ritonavir (1.5%; P  <   0.001) were observed in the partially non-adherent group. Two hundred and ninety patients were included in the follow-up study (64.1% male, median age 40 years). Patients in the adherent group had a higher chance of viral control [81.9% (167/204)] versus the partially non-adherent group and the non-adherent group [71.7% (33/46) and 53.1% (17/32), respectively; P  =   0.001]. Based on multivariate analysis, baseline HIV RNA >50 copies/mL ( P  <   0.001), genotypic susceptibility score ≤2 ( P  =   0.001), lower nadir CD4 cell count ( P  =   0.003) and not being in the adherent group ( P  =   0.029) were independent predictors of HIV RNA >50 copies/mL at 48 weeks. Conclusions The measurement of PI and ritonavir plasma levels can uncover incomplete compliance with treatment; TDM may represent a useful tool for identifying patients in need of adherence-promoting interventions.