Randomized, open-label, phase 2a study to evaluate the contribution of artefenomel to the clinical and parasiticidal activity of artefenomel plus ferroquine in African patients with uncomplicated Plasmodium falciparum malaria.

BACKGROUND: The contribution of artefenomel to the clinical and parasiticidal activity of ferroquine and artefenomel in combination in uncomplicated Plasmodium falciparum malaria was investigated. METHODS: This Phase 2a, randomized, open-label, parallel-group study was conducted from 11th September 2018 to 6th November 2019 across seven centres in Benin, Burkina Faso, Gabon, Kenya, and Uganda. Patients aged ≥ 14-69 years with microscopically confirmed infection (≥ 3000 to ≤ 50,000 parasites/µL blood) were randomized 1:1:1:1 to 400 mg ferroquine, or 400 mg ferroquine plus artefenomel 300, 600, or 1000 mg, administered as a single oral dose. The primary efficacy analysis was a logistic regression evaluating the contribution of artefenomel exposure to Day 28 PCR-adjusted adequate clinical and parasitological response (ACPR). Safety was also evaluated. RESULTS: The randomized population included 140 patients. For the primary analysis in the pharmacokinetic/pharmacodynamic efficacy population (N = 121), the contribution of artefenomel AUC0-∞ to Day 28 PCR-adjusted ACPR was not demonstrated when accounting for ferroquine AUC0-d28, baseline parasitaemia, and other model covariates: odds ratio 1.1 (95% CI 0.98, 1.2; P = 0.245). In the per-protocol population, Day 28 PCR-adjusted ACPR was 80.8% (21/26; 95% CI 60.6, 93.4) with ferroquine alone and 90.3% (28/31; 95% CI 74.2, 98.0), 90.9% (30/33; 95% CI 75.7, 98.1) and 87.1% (27/31; 95% CI 70.2, 96.4) with 300, 600, and 1000 mg artefenomel, respectively. Median time to parasite clearance (Kaplan-Meier) was 56.1 h with ferroquine, more rapid with artefenomel, but similar for all doses (30.0 h). There were no deaths. Adverse events (AEs) of any cause occurred in 51.4% (18/35) of patients with ferroquine 400 mg alone, and 58.3% (21/36), 66.7% (24/36), and 72.7% (24/33) with 300, 600, and 1000 mg artefenomel, respectively. All AEs were of mild-to-moderate severity, and consistent with the known profiles of the compounds. Vomiting was the most reported AE. There were no cases of QTcF prolongation ≥ 500 ms or > 60 ms from baseline. CONCLUSION: The contribution of artefenomel exposure to the clinical and parasitological activity of ferroquine/artefenomel could not be demonstrated in this study. Parasite clearance was faster with ferroquine/artefenomel versus ferroquine alone. All treatments were well tolerated. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03660839 (7 September, 2018).

Preclinical characterization and target validation of the antimalarial pantothenamide MMV693183.

Drug resistance and a dire lack of transmission-blocking antimalarials hamper malaria elimination. Here, we present the pantothenamide MMV693183 as a first-in-class acetyl-CoA synthetase (AcAS) inhibitor to enter preclinical development. Our studies demonstrate attractive drug-like properties and in vivo efficacy in a humanized mouse model of Plasmodium falciparum infection. The compound shows single digit nanomolar in vitro activity against P. falciparum and P. vivax clinical isolates, and potently blocks P. falciparum transmission to Anopheles mosquitoes. Genetic and biochemical studies identify AcAS as the target of the MMV693183-derived antimetabolite, CoA-MMV693183. Pharmacokinetic-pharmacodynamic modelling predict that a single 30 mg oral dose is sufficient to cure a malaria infection in humans. Toxicology studies in rats indicate a > 30-fold safety margin in relation to the predicted human efficacious exposure. In conclusion, MMV693183 represents a promising candidate for further (pre)clinical development with a novel mode of action for treatment of malaria and blocking transmission.

Safety, pharmacokinetics, and antimalarial activity of the novel triaminopyrimidine ZY-19489: a first-in-human, randomised, placebo-controlled, double-blind, single ascending dose study, pilot food-effect study, and volunteer infection study.

BACKGROUND: New antimalarials with novel mechanisms of action are needed to combat the emergence of drug resistance. Triaminopyrimidines comprise a novel antimalarial class identified in a high-throughput screen against asexual blood-stage Plasmodium falciparum. This first-in-human study aimed to characterise the safety, pharmacokinetics, and antimalarial activity of the triaminopyrimidine ZY-19489 in healthy volunteers. METHODS: A three-part clinical trial was conducted in healthy adults (aged 18-55 years) in Brisbane, QLD, Australia. Part one was a double-blind, randomised, placebo-controlled, single ascending dose study in which participants enrolled into one of six dose groups (25, 75, 150, 450, 900, or 1500 mg) were randomly assigned (3:1) to ZY-19489 or placebo. Part two was an open-label, randomised, two-period cross-over, pilot food-effect study in which participants were randomly assigned (1:1) to a fasted-fed or a fed-fasted sequence. Part three was an open-label, randomised, volunteer infection study using the P falciparum induced blood-stage malaria model in which participants were enrolled into one of two cohorts, with participants in cohort one all receiving the same dose of ZY-19489 and participants in cohort two randomly assigned to receive one of two doses. The primary outcome for all three parts was the incidence, severity, and relationship to ZY-19489 of adverse events. Secondary outcomes were estimation of ZY-19489 pharmacokinetic parameters for all parts; how these parameters were affected by the fed state for part two only; and the parasite reduction ratio, parasite clearance half-life, recrudescent parasitaemia, and pharmacokinetic-pharmacodynamic modelling parameters for part three only. This trial is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12619000127101, ACTRN12619001466134, and ACTRN12619001215112). FINDINGS: 48 participants were enrolled in part one (eight per cohort for 25-1500 mg cohorts), eight in part two (four in each group, all dosed with 300 mg), and 15 in part three (five dosed with 200 mg, eight with 300 mg, and two with 900 mg). In part one, the incidence of drug-related adverse events was higher in the 1500 mg dose group (occurring in all six participants) than in lower-dose groups and the placebo group (occurring in one of six in the 25 mg group, two of six in the 75 mg group, three of six in the 150 mg group, two of six in the 450 mg group, four of six in the 900 mg group, and four of 12 in the placebo group), due to the occurrence of mild gastrointestinal symptoms. Maximum plasma concentrations occurred 5-9 h post-dosing, and the elimination half-life was 50-97 h across the dose range. In part two, three of seven participants had a treatment-related adverse event in the fed state and four of eight in the fasted state. Dosing in the fed state delayed absorption (maximum plasma concentration occurred a median of 12·0 h [range 7·5-16·0] after dosing in the fed state vs 6·0 h [4·5-9·1] in the fasted state) but had no effect on overall exposure (difference in area under the concentration-time curve from time 0 [dosing] extrapolated to infinity between fed and fasted states was -0·013 [90% CI -0·11 to 0·08]). In part three, drug-related adverse events occurred in four of five participants in the 200 mg group, seven of eight in the 300 mg group, and both participants in the 900 mg group. Rapid initial parasite clearance occurred in all participants following dosing (clearance half-life 6·6 h [95% CI 6·2-6·9] for 200 mg, 6·8 h [95% CI 6·5-7·1] for 300 mg, and 7·1 h [95% CI 6·6-7·6] for 900 mg). Recrudescence occurred in four of five participants in the 200 mg group, five of eight in the 300 mg group, and neither of the two participants in the 900 mg group. Simulations done using a pharmacokinetic-pharmacodynamic model predicted that a single dose of 1100 mg would clear baseline parasitaemia by a factor of 109. INTERPRETATION: The safety, pharmacokinetic profile, and antimalarial activity of ZY-19489 in humans support the further development of the compound as a novel antimalarial therapy. FUNDING: Cadila Healthcare and Medicines for Malaria Venture.

Impact of Genetic and Nongenetic Factors on Body Mass Index and Waist-Hip Ratio Change in HIV-Infected Individuals Initiating Antiretroviral Therapy.

OBJECTIVE: There is limited data on abdominal obesity and the influence of genetics on weight change after antiretroviral therapy (ART) initiation. We assessed body mass index (BMI) and waist hip ration (WHR) change over time in the Swiss HIV Cohort study (SHCS). METHODS: Mixed-effects models characterizing BMI and WHR change over time in 1090 SHCS participants initiating ART between 2005 and 2015 were developed and used to quantify the influence of demographics, clinical factors, and genetic background. RESULTS: Individuals with CD4 nadir <100 cells/µL gained 6.4 times more BMI than individuals with ≥200, and 2.8 times more WHR than individuals with ≥100 (P < .001) during the first 1.5 and 2.5 years after ART initiation, respectively. The risk of being overweight or obese after 1.5 years increased with CD4 nadir <100 cells/µL compared to 100-199 (odds ratio [OR], 2.07; 95% confidence interval [CI], 1.63-2.74) and ≥200 (OR, 1.69; 95% CI, 1.26-2.32), persisting after 10 years of ART. The risk of abdominal obesity after 2.5 years increased with CD4 nadir <100 compared to ≥100 (OR, 1.35; 95% CI, 1.17-1.54 [in men]; OR, 1.36; 95% CI, 1.18-1.57 [in women]), persisting after 10 years of ART. No significant differences were found across antiretroviral drug classes or genetic scores. CONCLUSIONS: The risk of general and abdominal obesity increased with CD4 nadir <100 cells/µL. Based on our results, including the genetic background would not improve obesity predictions in HIV-infected individuals.

Contribution of Genetic Background and Data Collection on Adverse Events of Anti-human Immunodeficiency Virus (HIV) Drugs (D:A:D) Clinical Risk Score to Chronic Kidney Disease in Swiss HIV-infected Persons With Normal Baseline Estimated Glomerular Filtration Rate.

BACKGROUND: In human immunodeficiency virus (HIV), the relative contribution of genetic background, clinical risk factors, and antiretrovirals to chronic kidney disease (CKD) is unknown. METHODS: We applied a case-control design and performed genome-wide genotyping in white Swiss HIV Cohort participants with normal baseline estimated glomerular filtration rate (eGFR >90 mL/minute/1.73 m2). Univariable and multivariable CKD odds ratios (ORs) were calculated based on the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) score, which summarizes clinical CKD risk factors, and a polygenic risk score that summarizes genetic information from 86 613 single-nucleotide polymorphisms. RESULTS: We included 743 cases with confirmed eGFR drop to <60 mL/minute/1.73 m2 (n = 144) or ≥25% eGFR drop to <90 mL/minute/1.73 m2 (n = 599), and 322 controls (eGFR drop <15%). Polygenic risk score and D:A:D score contributed to CKD. In multivariable analysis, CKD ORs were 2.13 (95% confidence interval [CI], 1.55-2.97) in participants in the fourth (most unfavorable) vs first (most favorable) genetic score quartile; 1.94 (95% CI, 1.37-2.65) in the fourth vs first D:A:D score quartile; and 2.98 (95% CI, 2.02-4.66), 1.70 (95% CI, 1.29-2.29), and 1.83 (95% CI, 1.45-2.40), per 5 years of exposure to atazanavir/ritonavir, lopinavir/ritonavir, and tenofovir disoproxil fumarate, respectively. Participants in the first genetic score quartile had no increased CKD risk, even if they were in the fourth D:A:D score quartile. CONCLUSIONS: Genetic score increased CKD risk similar to clinical D:A:D score and potentially nephrotoxic antiretrovirals. Irrespective of D:A:D score, individuals with the most favorable genetic background may be protected against CKD.

Population pharmacokinetics of dolutegravir: influence of drug-drug interactions in a real-life setting.

OBJECTIVES: Dolutegravir is widely prescribed owing to its potent antiviral activity, high genetic barrier and good tolerability. The aim of this study was to characterize dolutegravir's pharmacokinetic profile and variability in a real-life setting and to identify individual factors and co-medications affecting dolutegravir disposition. METHODS: A population pharmacokinetic model was developed using NONMEM®. Relevant demographic factors, clinical factors and co-medications were tested as potential covariates. Simulations based on the final model served to compare expected dolutegravir concentrations under standard and alternative dosage regimens in the case of drug-drug interactions. RESULTS: A total of 620 dolutegravir plasma concentrations were collected from 521 HIV-infected individuals under steady-state conditions. A one-compartment model with first-order absorption and elimination best characterized dolutegravir pharmacokinetics. Typical dolutegravir apparent clearance (CL/F) was 0.93 L/h with 32% between-subject variability, the apparent volume of distribution was 20.2 L and the absorption rate constant was fixed to 2.24 h-1. Older age, higher body weight and current smoking were associated with higher CL/F. Atazanavir co-administration decreased dolutegravir CL/F by 38%, while darunavir modestly increased CL/F by 14%. Rifampicin co-administration showed the largest impact on CL/F. Simulations suggest that average dolutegravir trough concentrations are 63% lower after 50 mg/12h with rifampicin compared with a standard dosage of 50 mg/24h without rifampicin. Average trough concentrations after 100 mg/24h and 100 mg/12h with rifampicin are 92% and 25% lower than the standard dosage without rifampicin, respectively. CONCLUSIONS: Patients co-treated with dolutegravir and rifampicin might benefit from therapeutic drug monitoring and individualized dosage increase, up to 100 mg/12 h in some cases.

Multiparametric magnetic resonance imaging in prostate cancer detection.

OBJECTIVES: The prostate cancer screening based on systematic biopsies in patients with elevated PSA values has low sensitivity and low specificity. We assessed the use of multiparametric magnetic resonance imaging (mpMRI) as a screening tool for prostate cancer detection. METHODS: We retrospectively analyzed a cohort of patients with suspicious signs of prostate cancer who underwent prostate mpMRI before the biopsy. Patients underwent either targeted biopsy or systematic biopsy, depending on the presence or not of mpMRI lesions. Cancer diagnosis was confirmed from pathologic findings in biopsy samples. RESULTS: The final record included 148 patients with a median of 3 previous negative biopsies (IQR 1-5).Cancer was diagnosed in 21 patients (14%); of them, 18 had highly suspicious mpMRI lesions (53% positive predictive value), 2 had lesions of other suspicion degree, and one had no mpMRI lesions. Cancer diagnosis was ruled out in 111 patients over 114 without highly suspicious mpMRI lesions (97% negative predictive value). In a multivariate analysis including PSA levels, abnormal DRE, the presence of mpMRI lesions, and the presence of highly suspicious mpMRI lesions, only the presence of highly suspicious mpMRI lesions significantly predicted cancer diagnosis. CONCLUSIONS: The identification of highly suspicious lesions in prostate mpMRI examination has moderate sensitivity and high specificity in the detection of prostate cancer in patients with multiple previous negative biopsies. The use of mpMRI should be considered as a screening tool for prostate cancer in routine clinical practice.

OBJETIVOS: El cribado de cáncer de próstata basado en biopsias sistemáticas en pacientes con valores de PSA elevados tiene baja sensibilidad y especificidad. Evaluamos la utilización de RMN multiparamétrica (RMN mp) como herramienta de cribado para la detección del cáncer de próstata. MÉTODOS: Analizamos retrospectivamente una cohorte de pacientes con signos sospechosos de cáncer de próstata que fueron sometidos a RMNmp de próstata antes de la biopsia. Los pacientes fueron sometidos a biopsia dirigida o sistemática, dependiendo de la presencia o no de lesiones en la RMNmp. El diagnóstico de cáncer se confirmó por los hallazgos patológicos en las muestras de biopsia. RESULTADOS: El registro final incluyó 148 pacientes con una mediana de biopsias previas negativas de 3 (RIQ 1-5). Se diagnosticó cáncer en 21 pacientes (14%); de ellos, 18 tenían lesiones altamente sospechosas en la RMNmp (VPP 53%), 2 tenían lesiones con otro nivel de sospecha, y uno no tenía lesiones en la RMNmp. El diagnóstico de cáncer fue descartado en 111 pacientes de 114 que no tenían lesiones altamente sospechosas (VPN 97%). En el estudio multivariante incluyendo los niveles de PSA, el TR anormal, la presencia de lesiones en RMNmp y de lesiones altamente sospechosas, sólo esta última predijo el diagnóstico de cáncer. CONCLUSIONES: La identificación de lesiones altamente sospechosas en la RMNmp tiene una sensibilidad moderada y alta especificidad en la detección de cáncer de próstata en pacientes con múltiples biopsias negativas previas. El uso de RMNmp debe ser considerado en la práctica clínica habitual como una herramienta de cribado para el cáncer de próstata.

Multiparametric magnetic resonance imaging in prostate cancer detection / Resonancia magnética multiparamétrica en la detección del cáncer de prostata

Objectives: The prostate cancer screening based on systematic biopsies in patients with elevated PSA values has low sensitivity and low specificity. We assessed the use of multiparametric magnetic resonance imaging (mpMRI) as a screening tool for prostate cancer detection. Methods: We retrospectively analyzed a cohort of patients with suspicious signs of prostate cancer who underwent prostate mpMRI before the biopsy. Patients underwent either targeted biopsy or systematic biopsy, depending on the presence or not of mpMRI lesions. Cancer diagnosis was confirmed from pathologic findings in biopsy samples. RESULTS: The final record included 148 patients with a median of 3 previous negative biopsies (IQR 1-5).Cancer was diagnosed in 21 patients (14%); of them, 18 had highly suspicious mpMRI lesions (53% positive predictive value), 2 had lesions of other suspicion degree, and one had no mpMRI lesions. Cancer diagnosis was ruled out in 111 patients over 114 without highly suspicious mpMRI lesions (97% negative predictive value). In a multivariate analysis including PSA levels, abnormal DRE, the presence of mpMRI lesions, and the presence of highly suspicious mpMRI lesions, only the presence of highly suspicious mpMRI lesions significantly predicted cancer diagnosis. Conclusions: The identification of highly suspicious lesions in prostate mpMRI examination has moderate sensitivity and high specificity in the detection of prostate cancer in patients with multiple previous negative biopsies. The use of mpMRI should be considered as a screening tool for prostate cancer in routine clinical practice

Objetivos: El cribado de cáncer de próstata basado en biopsias sistemáticas en pacientes con valores de PSA elevados tiene baja sensibilidad y especificidad. Evaluamos la utilización de RMN multiparamétrica (RMN mp) como herramienta de cribado para la detección del cáncer de próstata. Métodos: Analizamos retrospectivamente una cohorte de pacientes con signos sospechosos de cáncer de próstata que fueron sometidos a RMNmp de próstata antes de la biopsia. Los pacientes fueron sometidos a biopsia dirigida o sistemática, dependiendo de la presencia o no de lesiones en la RMNmp. El diagnóstico de cáncer se confirmó por los hallazgos patológicos en las muestras de biopsia. Resultados: El registro final incluyó 148 pacientes con una mediana de biopsias previas negativas de 3 (RIQ 1-5). Se diagnosticó cáncer en 21 pacientes (14%); de ellos, 18 tenían lesiones altamente sospechosas en la RMNmp (VPP 53%), 2 tenían lesiones con otro nivel de sospecha, y uno no tenía lesiones en la RMNmp. El diagnóstico de cáncer fue descartado en 111 pacientes de 114 que no tenían lesiones altamente sospechosas (VPN 97%). En el estudio multivariante incluyendo los niveles de PSA, el TR anormal, la presencia de lesiones en RMNmp y de lesiones altamente sospechosas, sólo esta última predijo el diagnóstico de cáncer. Conclusiones: La identificación de lesiones altamente sospechosas en la RMNmp tiene una sensibilidad moderada y alta especificidad en la detección de cáncer de próstata en pacientes con múltiples biopsias negativas previas. El uso de RMNmp debe ser considerado en la práctica clínica habitual como una herramienta de cribado para el cáncer de próstata

Population Pharmacokinetics and Pharmacogenetics Analysis of Rilpivirine in HIV-1-Infected Individuals.

Rilpivirine (RPV), the latest nonnucleoside reverse transcriptase inhibitor active against HIV-1, is prescribed in a standard dosage of 25 mg once a day in combination with emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF). The aim of this observational study was to characterize the RPV pharmacokinetic profile, to quantify interpatient variability, and to identify potential factors that could influence drug exposure. RPV concentration data were collected from HIV-infected patients as part of routine therapeutic drug monitoring performed in our center (Laboratory of Clinical Pharmacology). A population pharmacokinetic analysis was performed with NONMEM by comparing various structural models. The influence of demographic and clinical covariates, as well as frequent genetic polymorphisms in 5 genes (CYP3A4*22, CYP3A5*3, CYP2C19*2, CYP2C19*17, UGT1A1*28, and UGT1A4*2), on RPV elimination was explored. A total of 325 plasma concentration measurements were obtained from 249 HIV-positive patients. Plasma concentrations ranged from 12 to 255 ng/ml. A one-compartment model with zero-order absorption best characterized RPV pharmacokinetics. The average RPV clearance (CL) was 11.7 liters/h, the average volume of distribution was 401 liters, and the mean absorption time was 4 h. The interinterindividual variability (IIV) for CL was estimated to be 33%. None of the available demographic or genetic covariates showed any influence on RPV pharmacokinetics, but 29% of the patients were predicted to present minimal concentrations below the recently identified target cutoff value of 50 ng/ml. The variability in RPV pharmacokinetics appears to be lower than that for most other antiretroviral drugs. However, under the standard regimen of 25 mg daily, a significant number of patients might be underdosed. It remains to be investigated whether the underexposure has an impact on the development of resistance while patients are on maintenance therapy.

Contribution of Genetic Background and Clinical Risk Factors to Low-Trauma Fractures in Human Immunodeficiency Virus (HIV)-Positive Persons: The Swiss HIV Cohort Study.

Background. The impact of human genetic background on low-trauma fracture (LTF) risk has not been evaluated in the context of human immunodeficiency virus (HIV) and clinical LTF risk factors. Methods. In the general population, 6 common single-nucleotide polymorphisms (SNPs) associate with LTF through genome-wide association study. Using genome-wide SNP arrays and imputation, we genotyped these SNPs in HIV-positive, white Swiss HIV Cohort Study participants. We included 103 individuals with a first, physician-validated LTF and 206 controls matched on gender, whose duration of observation and whose antiretroviral therapy start dates were similar using incidence density sampling. Analyses of nongenetic LTF risk factors were based on 158 cases and 788 controls. Results. A genetic risk score built from the 6 LTF-associated SNPs did not associate with LTF risk, in both models including and not including parental hip fracture history. The contribution of clinical LTF risk factors was limited in our dataset. Conclusions. Genetic LTF markers with a modest effect size in the general population do not improve fracture prediction in persons with HIV, in whom clinical LTF risk factors are prevalent in both cases and controls.

Population pharmacokinetic analysis of elvitegravir and cobicistat in HIV-1-infected individuals.

OBJECTIVES: Co-formulated elvitegravir, cobicistat, tenofovir disoproxil fumarate and emtricitabine is among the preferred regimens for first-line ART. A population approach was used to characterize the pharmacokinetics of elvitegravir and cobicistat and identify individual factors and co-medications influencing their disposition, taking into consideration the interaction between the two compounds. METHODS: The study population included 144 HIV-infected individuals who provided 186 and 167 elvitegravir and cobicistat plasma concentrations, respectively. First, distinct NONMEM(®) analyses were conducted for elvitegravir and cobicistat, including individual demographic, clinical and genetic factors as potential covariates. Elvitegravir and cobicistat interaction was then assessed through different inhibitory models. Simulations based on the final model served to compare expected drug concentrations under standard and alternative dosage regimens. RESULTS: Clearance with between-subject variability was 7.6 L/h [coefficient of variation (CV) 16.6%] and volume of distribution 61 L for elvitegravir and 16.0 L/h (CV 41.9%) and 88.3 L, respectively, for cobicistat. Concomitant administration of non-ritonavir-boosted atazanavir decreased elvitegravir clearance by 35%, likely due to UDP-glucuronosyl transferase (UGT) 1A1 inhibition. Concomitant administration of non-ritonavir-boosted atazanavir and ritonavir-boosted darunavir decreased cobicistat clearance by 47% and 27%, respectively. The final interaction model included cobicistat exposure (AUC0-24) on elvitegravir clearance. Simulations confirmed that a reduced elvitegravir dose of 85 mg co-administered with cobicistat and atazanavir produces a concentration-time course comparable to the standard regimen without atazanavir. CONCLUSIONS: Elvitegravir and cobicistat pharmacokinetic variability appears to be mainly explained by drug-drug interactions that may be encountered in routine clinical practice. In these cases, therapeutic drug monitoring and surveillance for potential toxicities would be justified.

In Vivo Profiling and Distribution of Known and Novel Phase I and Phase II Metabolites of Efavirenz in Plasma, Urine, and Cerebrospinal Fluid.

Efavirenz (EFV) is principally metabolized by CYP2B6 to 8-hydroxy-efavirenz (8OH-EFV) and to a lesser extent by CYP2A6 to 7-hydroxy-efavirenz (7OH-EFV). So far, most metabolite profile analyses have been restricted to 8OH-EFV, 7OH-EFV, and EFV-N-glucuronide, even though these metabolites represent a minor percentage of EFV metabolites present in vivo. We have performed a quantitative phase I and II metabolite profile analysis by tandem mass spectrometry of plasma, cerebrospinal fluid (CSF), and urine samples in 71 human immunodeficiency virus patients taking efavirenz, prior to and after enzymatic (glucuronidase and sulfatase) hydrolysis. We have shown that phase II metabolites constitute the major part of the known circulating efavirenz species in humans. The 8OH-EFV-glucuronide (gln) and 8OH-EFV-sulfate (identified for the first time) in humans were found to be 64- and 7-fold higher than the parent 8OH-EFV, respectively. In individuals (n = 67) genotyped for CYP2B6, 2A6, and CYP3A metabolic pathways, 8OH-EFV/EFV ratios in plasma were an index of CYP2B6 phenotypic activity (P < 0.0001), which was also reflected by phase II metabolites 8OH-EFV-glucuronide/EFV and 8OH-EFV-sulfate/EFV ratios. Neither EFV nor 8OH-EFV, nor any other considered metabolites in plasma were associated with an increased risk of central nervous system (CNS) toxicity. In CSF, 8OH-EFV levels were not influenced by CYP2B6 genotypes and did not predict CNS toxicity. The phase II metabolites 8OH-EFV-gln, 8OH-EFV-sulfate, and 7OH-EFV-gln were present in CSF at 2- to 9-fold higher concentrations than 8OH-EFV. The potential contribution of known and previously unreported EFV metabolites in CSF to the neuropsychological effects of efavirenz needs to be further examined in larger cohort studies.

Synergism between the brushite and hydroxyapatite urinary crystallization inhibitors.

The aim of this paper is to study possible synergic effects between crystallization-inhibitor molecules of low molecular weight on the hydroxyapatite and brushite crystal nucleation. Kinetic-turbidimetric measurements were performed to follow the nucleation process in synthetic urine at 37 degrees C. Only pyrophosphate + phytate mixture manifested synergic effects on the brushite nucleation, whereas the mixture pyrophosphate + citrate exhibited synergic effects only on the hydroxyapatite nucleation. It seems clear that synergic effects between the crystallization inhibitory capacity of some substances in urine can take place and as a consequence, the high crystallization inhibitory capacity of healthy urine could be assigned not only to the individual inhibitory capacity of each product but also to the synergic effects between different products.