Conformationally restricted κ-opioid receptor agonists: Synthesis and pharmacological evaluation of diastereoisomeric and enantiomeric decahydroquinoxalines.

All diastereoisomeric decahydroquinoxalines representing conformationally restricted analogs of κ agonists U-50,488 and GR-89,696 have been prepared. Cis/trans configured compound 7 is by far the highest binding diastereoisomer with a Ki of 0.35 nM. Racemates 4, 6, and 7 were separated into enantiomers. (+)-(4aR,5S,8aS)-Configured enantiomer 7b was identified as a high affinity (Ki=0.25 nM) κ ligand with high selectivity over µ and δ receptors. It acts as full agonist with an EC50 value of 2.0 nM in the [(35)S]GTPγS assay, while enantiomer 7a showed an EC50 value of 1000 nM.

Population pharmacokinetics of ritonavir-boosted saquinavir regimens in HIV-infected individuals.

OBJECTIVES: The aim of this study was to develop and validate a population pharmacokinetic model in order to describe ritonavir-boosted saquinavir concentrations dosed twice and once daily in human immunodeficiency virus (HIV)-infected patients from the UK, Uganda and Thailand and to identify factors that may influence saquinavir pharmacokinetics. METHODS: Pharmacokinetic data from 10 clinical studies were combined. Non-linear mixed effects modelling (NONMEM version V) was applied to determine the saquinavir pharmacokinetic parameters, interindividual/interoccasion variability (IIV/IOV) and residual error. Various covariates potentially related to saquinavir pharmacokinetics were explored, and the final model was validated by means of 95% prediction interval and testing the predictive performance of the model with data not included in the model-building process. RESULTS: Ninety-seven patients were included from the UK (n = 52), Uganda (n = 18) and Thailand (n = 27), contributing 347 saquinavir profiles (1-14 profiles per patient). A one-compartment model with zero-order absorption and lag-time best described the data with IIV/IOV on apparent oral clearance (CL/F) and volume of distribution (V/F) and with IIV on duration and absorption lag-time. The ritonavir area under the curve over the dosing interval was significantly associated with saquinavir CL/F and V/F. A typical patient from the UK had approximately 1.5- and 3-fold higher saquinavir CL/F compared with patients from Uganda (89.0 versus 49.8 L/h) and Thailand (89.0 versus 26.7 L/h), respectively. CONCLUSIONS: A model to characterize ritonavir-boosted saquinavir pharmacokinetics in HIV-infected adults has been developed and validated. The model could be used for dosage adaptation following therapeutic drug monitoring and to assess patients' suitability for once-daily boosted saquinavir therapy.

Pharmacokinetics and short-term efficacy of a double-boosted protease inhibitor regimen in treatment-naive HIV-1-infected adults.

OBJECTIVES: To study the pharmacokinetics and short-term efficacy of low and standard dose lopinavir/ritonavir and saquinavir combinations in Thai, human immunodeficiency virus (HIV)-infected, treatment-naive patients. METHODS: In this open-label, 24-week, prospective study, 48 treatment-naive patients were randomized to lopinavir/ritonavir 400/100 mg+saquinavir 1000 mg twice daily (arm A), lopinavir/ritonavir 400/100 mg+saquinavir 600 mg twice daily (arm B), lopinavir/ritonavir 266/66 mg+saquinavir 1000 mg twice daily (arm C), or lopinavir/ritonavir 266/66 mg+saquinavir 600 mg twice daily (arm D). A 12 h. pharmacokinetic profile in all patients was performed. Plasma concentrations of saquinavir and lopinavir were determined using an HPLC technique. HIV-1 RNA was measured over 24 weeks. RESULTS: Forty-three subjects were included in the pharmacokinetic analysis. The total exposure differed significantly for the different arms. Median values for lopinavir area under the curve at 0-12 h were 128.2, 119.2, 66.1 and 68.5 mg.h/L for arms A-D, respectively. For saquinavir, the median values were 36.9, 19.2, 25.3 and 12.4 mg.h/L for arms A-D, respectively. The proportion of patients having a viral load below 50 copies/mL at week 24 was 39% for arm A, 63% for arm B, 55.0% for arm C, and 69% for arm D. CONCLUSIONS: The pharmacokinetic parameters for the different treatment arms were adequate. However, the proportion of subjects with an undectable viral load at week 24 was lower than anticipated.

Ketoconazole is inferior to ritonavir as an alternative booster for saquinavir in a once daily regimen in Thai HIV-1 infected patients.

OBJECTIVE: To improve the pharmacokinetics of protease inhibitors, boosting with low-dose ritonavir is performed. However, toxicity, storage conditions and high costs of antiretroviral treatment may necessitate interruption of ritonavir. Ketoconazole was investigated as a potential booster of once-daily (o.d.) saquinavir. METHODS: In a single-group, two-period design, 25 virologically and immunologically stable patients on saquinavir/ritonavir 2000/100 mg o.d. were switched to saquinavir/ketoconazole 2000/400 mg o.d. for 2 weeks. Two steady-state pharmacokinetic curves were recorded at both periods. RESULTS: Fourteen females and 11 male patients were included. Median age was 34 years [interquartile range (IQR), 32-42 years], body weight 54 kg (IQR, 47-59 kg) and body mass index 21 kg/m (19-23 kg/m). The mean saquinavir area under the curve (AUC) during boosting with ritonavir was 57.93 +/- 27.96 mg/h/l, maximum observed concentration (Cmax) was 7.50 +/- 3.45 mg/l and concentration at 24 h (Cmin) was 0.35 +/- 0.30 mg/l. When ketoconazole was used, the saquinavir AUC, Cmax, and Cmin were 12.00 +/- 6.97 mg/h/l, 2.43 +/- 1.35 mg/l and 0.03 +/- 0.04 mg/l, respectively. CONCLUSION: Boosting with ketoconazole resulted in 80% lower exposure to saquinavir. Although saquinavir AUC might still be adequate for treatment, concentrations at 24 h reached levels below the recommended trough concentrations of 0.1 mg/l, which may result in selection of resistant HIV-1 viral strains. Therefore, boosting of saquinavir by ketoconazole is not recommended.

Relationships between drug exposure, changes in metabolic parameters and body fat in HIV-infected patients switched to a nucleoside sparing regimen.

BACKGROUND: The pathogenesis of metabolic disturbances in treated HIV infection is incompletely understood. METHODS: Relationships between fasted metabolic parameters, body composition, and drug plasma concentrations were investigated in 59 patients who switched from failed nucleoside analogue treatment to ritonavir-boosted indinavir and efavirenz therapy. Metabolic parameters, peripheral fat, visceral adipose tissue (VAT) and drug plasma concentrations were measured prospectively. RESULTS: Ritonavir exposure was found to be negatively correlated with high-density lipoprotein cholesterol (HDL-c) changes, with a 2.4% decrease in HDL-c for each unit increase in ritonavir concentration ratio. Significant associations between indinavir or efavirenz concentrations and metabolic disturbances were not observed. Total cholesterol (TC) correlated positively with high body mass index (BMI) and negatively with baseline limb fat mass: each unit increase in BMI and each kilogram reduction in baseline limb fat corresponded with a TC increase of 2.4% and 4.1%, respectively. Baseline triglyceride levels were lower in those patients with relatively greater limb fat mass: each kilogram reduction of total limb fat mass was associated with a 15.7% increase in triglyceride concentration. Changes in VAT were positively correlated with TC: for every unit TC increase a 0.3% VAT increase was observed (over 48 weeks). CONCLUSIONS: Reduced limb fat mass at the start of the study treatment, increases in VAT mass, and higher plasma concentrations of ritonavir on study treatment were each--to varying degrees--associated with various metabolic disturbances.

Design and Synthesis of Enantiomerically Pure Decahydroquinoxalines as Potent and Selective κ-Opioid Receptor Agonists with Anti-Inflammatory Activity in Vivo.

In order to develop novel κ agonists restricted to the periphery, a diastereo- and enantioselective synthesis of (4aR,5S,8aS)-configured decahydroquinoxalines 5-8 was developed. Physicochemical and pharmacological properties were fine-tuned by structural modifications in the arylacetamide and amine part of the pharmacophore as well as in the amine part outside the pharmacophore. The decahydroquinoxalines 5-8 show single-digit nanomolar to subnanomolar κ-opioid receptor affinity, full κ agonistic activity in the [35S]GTPγS assay, and high selectivity over µ, δ, σ1, and σ2 receptors as well as the PCP binding site of the NMDA receptor. Several analogues were selective for the periphery. The anti-inflammatory activity of 5-8 after topical application was investigated in two mouse models of dermatitis. The methanesulfonamide 8a containing the (S)-configured hydroxypyrrolidine ring was identified as a potent (Ki = 0.63 nM) and highly selective κ agonist (EC50 = 1.8 nM) selective for the periphery with dose-dependent anti-inflammatory activity in acute and chronic skin inflammation.

MLL-SEPTIN6 fusion recurs in novel translocation of chromosomes 3, X, and 11 in infant acute myelomonocytic leukaemia and in t(X;11) in infant acute myeloid leukaemia, and MLL genomic breakpoint in complex MLL-SEPTIN6 rearrangement is a DNA topoisomerase II cleavage site.

We examined the MLL translocation in two cases of infant AML with X chromosome disruption. The G-banded karyotype in the first case suggested t(X;3)(q22;p21)ins(X;11)(q22;q13q25). Southern blot analysis showed one MLL rearrangement. Panhandle PCR approaches were used to identify the MLL fusion transcript and MLL genomic breakpoint junction. SEPTIN6 from chromosome band Xq24 was the partner gene of MLL. MLL exon 7 was joined in-frame to SEPTIN6 exon 2 in the fusion transcript. The MLL genomic breakpoint was in intron 7; the SEPTIN6 genomic breakpoint was in intron 1. Spectral karyotyping revealed a complex rearrangement disrupting band 11q23. FISH with a probe for MLL confirmed MLL involvement and showed that the MLL-SEPTIN6 junction was on the der(X). The MLL genomic breakpoint was a functional DNA topoisomerase II cleavage site in an in vitro assay. In the second case, the karyotype revealed t(X;11)(q22;q23). Southern blot analysis showed two MLL rearrangements. cDNA panhandle PCR detected a transcript fusing MLL exon 8 in-frame to SEPTIN6 exon 2. MLL and SEPTIN6 are vulnerable to damage to form recurrent translocations in infant AML. Identification of SEPTIN6 and the SEPTIN family members hCDCrel and MSF as partner genes of MLL suggests a common pathway to leukaemogenesis.

Nevirapine plasma concentrations and concomitant use of rifampin in patients coinfected with HIV-1 and tuberculosis.

OBJECTIVES: In countries with high numbers of HIV/tuberculosis coinfection nevirapine and rifampin are used extensively. However, limited data are available about whether or not nevirapine and rifampin can be safely coadministered without the plasma concentration of nevirapine falling below therapeutic levels. METHODS: Blood samples for determination of nevirapine plasma concentrations were collected from patients using nevirapine 200 mg twice daily with or without concomitant rifampin. Bivariate and multivariate linear regression models were used to investigate factors possibly related to nevirapine concentrations. RESULTS: We received 74 blood samples from patients using nevirapine plus rifampin, and collected blood samples from an equal number of controls using nevirapine only. Groups were similar for age, gender, weight, height and body mass index (BMI). In the rifampin group the mean nevirapine concentration was 5.47 +/- 2.66 mg/l, whereas in the control group the mean nevirapine concentration was 8.72 +/- 3.98 mg/l. In the rifampin group seven nevirapine trough concentrations were low (< 3.1 mg/l), while in the control group two patients had low nevirapine trough concentrations (P = 0.164). In the multivariate linear regression analysis, corrected for time after drug intake, the use of rifampin was significantly (P < 0.001) associated with lower nevirapine plasma concentrations, whereas higher BMI reached borderline significance (P = 0.065). CONCLUSION: Although nevirapine plasma concentrations were 3.3 mg/l lower when co-administered with rifampin, still more than 86% of these patients had nevirapine plasma concentrations > 3.1 mg/l. Our results suggest that from a pharmacological point of view the majority of Thai coinfected patients, who have low BMIs, reach nevirapine plasma concentrations that are adequate for treatment of HIV. However this can only be undertaken if nevirapine plasma concentration monitoring is available and can be closely followed.

A facile synthesis of the GalNAcbeta1-->4Gal target sequence of respiratory pathogens.

The carbohydrate sequence, GalNAcbeta1-->4Gal, is the target for the adhesion of several respiratory pathogens. The sequence was prepared in an optimized synthesis in forms that allow conjugation to scaffolds or surfaces.

Identification of laminin-binding motifs of Yersinia pestis plasminogen activator by phage display.

Yersinia pestis plasminogen activator (Pla), a surface virulence factor contributes to the highly invasive nature of the pathogen by binding various tissue matrix components. In this study we characterised the laminin-binding site(s) of Pla via phage display and alanine-scanning mutagenesis. Previously we isolated 18 different heptamer peptide sequences from a phage display library with biopanning on laminin, and have shown that two of them with sequences of WSLLTPA or YPYIPTL completely inhibited laminin binding of a Pla-expressing recombinant Escherichia coli strain. These phages themselves strongly bound laminin in an ELISA assay utilising horseradish peroxidase-labelled anti-M 13 antibody. In the present study, with the application of synthetic peptides, a 55% and a 33% inhibition was demonstrated using WSLLTPA and YPYIPTL, respectively. Peptide pattern alignment showed two homologous regions for WSLLTPA and one for YPYIPTL inside the Pla sequence. Amino acids were changed for alanine in one of the WSLLTPA regions and in the YPYIPTL region in order to prove the role of the LTP/PTL motifs in laminin binding. Of the four constructed mutants, the triple mutant L65A-T66A-L67A in the WSLLTPA region and the double mutant G178A-L179A in the YPYIPTL region decreased the laminin binding capacity of the Pla-expressing recombinant E. coli by about 50%.

Interindividual variability of once-daily ritonavir boosted saquinavir pharmacokinetics in Thai and UK patients.

OBJECTIVES: Differential exposure to saquinavir/ritonavir may lead to therapy failure. The objective was to identify factors that influence variability of saquinavir/ritonavir plasma concentrations. METHODS: Saquinavir/ritonavir data, dosed as 1600/100 mg once daily, from three separate pharmacokinetic studies, in 45 patients from Thailand and the UK, were pooled. Pharmacokinetic parameters were based on non-compartmental analysis. Univariate analysis was performed with saquinavir as the dependent variable, and ritonavir area under the curve (AUC), gender, body weight, body mass index (BMI) and study site as independent variables. Variables with a P value <0.10 were included in a multivariate linear regression analysis. RESULTS: Higher saquinavir AUCs, maximum concentrations (Cmax) and minimum concentrations (Cmin) were seen in Thai patients than in UK patients. Univariate analysis showed associations between body weight, gender, study site and ritonavir AUC and saquinavir AUC (P < 0.05), whereas BMI (P = 0.13) did not. In the multivariate analysis, ritonavir AUC (P = 0.0001) and study site (P = 0.0021) were significantly related to saquinavir AUC (R2 = 0.50). CONCLUSIONS: The ritonavir AUC and study site appeared to be related to exposure of saquinavir. Study site should be viewed as the total of country- and study-specific differences--such as differences in lifestyle, environment, genetic background and dietary composition--between the analysed studies.

Adhesion inhibition of F1C-fimbriated Escherichia coli and Pseudomonas aeruginosa PAK and PAO by multivalent carbohydrate ligands.

In order to evaluate their inhibition of bacterial adhesion, the carbohydrate sequences GalNAcbeta1-->4Gal and GalNAcbeta1-->4Galbeta1-->4Glc were synthesized. The disaccharide was conjugated to dendrons based on the 3,5-di-(2-aminoethoxy)-benzoic acid branching unit to yield di- and tetravalent versions of these compounds. A divalent compound was also prepared that had significantly longer spacer arms. Relevant monovalent compounds were prepared for comparison. Their anti-adhesion properties against F1C-fimbriated uropathogenic Escherichia coli were evaluated in an ELISA-type assay by using a recombinant strain and also by using Pseudomonas aeruginosa strains PAO and PAK. Adhesion inhibition was observed in all cases, and multivalency effects of up to one order of magnitude were observed. The combination of spacer and multivalency effects led to a 38-fold increase in the potency of a divalent inhibitor with long spacer arms towards the PAO strain when compared with the free carbohydrate.