<Emphasis Type="Italic">In Vitro</Emphasis> and <Emphasis Type="Italic">In Vivo</Emphasis> Metabolite Identification Studies for the New Synthetic Opioids Acetylfentanyl,Acrylfentanyl, Furanylfentanyl,and 4-Fluoro-Isobutyrylfentanyl

New fentanyl analogs have recently emerged as new psychoactive substances and have caused numerous fatalities worldwide. To determine if the new analogs follow the same metabolic pathways elucidated for fentanyl and known fentanyl analogs, we performed in vitro and in vivo metabolite identification studies for acetylfentanyl, acrylfentanyl, 4-fluoro-isobutyrylfentanyl, and furanylfentanyl. All compounds were incubated at 10 μM with pooled human hepatocytes for up to 5 h. For each compound, four or five authentic human urine samples from autopsy cases with and without enzymatic hydrolysis were analyzed. Data acquisition was performed in data-dependent acquisition mode during liquid chromatography high-resolution mass spectrometry analyses. Data was analyzed (1) manually based on predicted biotransformations and (2) with MetaSense software using data-driven search algorithms. Acetylfentanyl, acrylfentanyl, and 4-fluoro-isobutyrylfentanyl were predominantly metabolized by N-dealkylation, cleaving off the phenethyl moiety, monohydroxylation at the ethyl linker and piperidine ring, as well as hydroxylation/methoxylation at the phenyl ring. In contrast, furanylfentanyl’s major metabolites were generated by amide hydrolysis and dihydrodiol formation, while the nor-metabolite was minor or not detected in case samples at all. In general, in vitro results matched the in vivo findings well, showing identical biotransformations in each system. Phase II conjugation was observed, particularly for acetylfentanyl. Based on our results, we suggest the following specific and abundant metabolites as analytical targets in urine: a hydroxymethoxy and monohydroxylated metabolite for acetylfentanyl, a monohydroxy and dihydroxy metabolite for acrylfentanyl, two monohydroxy metabolites and a hydroxymethoxy metabolite for 4-fluoro-isobutyrylfentanyl, and a dihydrodiol metabolite and the amide hydrolysis metabolite for furanylfentanyl.     

Challenges and Opportunities with Non-CYP Enzymes Aldehyde Oxidase,Carboxylesterase, and UDP-Glucuronosyltransferase: Focus on Reaction Phenotyping and Prediction of Human Clearance

Over the years, significant progress has been made in reducing metabolic instability due to cytochrome P450-mediated oxidation. High-throughput metabolic stability screening has enabled the advancement of compounds with little to no oxidative metabolism. Furthermore, high lipophilicity and low aqueous solubility of presently pursued chemotypes reduces the probability of renal excretion. As such, these low microsomal turnover compounds are often substrates for non-CYP-mediated metabolism. UGTs, esterases, and aldehyde oxidase are major enzymes involved in catalyzing such metabolism. Hepatocytes provide an excellent tool to identify such pathways including elucidation of major metabolites. To predict human PK parameters for P450-mediated metabolism, in vitro-in vivo extrapolation using hepatic microsomes, hepatocytes, and intestinal microsomes has been actively investigated. However, such methods have not been sufficiently evaluated for non-P450 enzymes. In addition to the involvement of the liver, extrahepatic enzymes (intestine, kidney, lung) are also likely to contribute to these pathways. While there has been considerable progress in predicting metabolic pathways and clearance primarily mediated by the liver, progress in characterizing extrahepatic metabolism and prediction of clearance has been slow. Well-characterized in vitro systems or in vivo animal models to assess drug-drug interaction potential and intersubject variability due to polymorphism are not available. Here we focus on the utility of appropriate in vitro studies to characterize non-CYP-mediated metabolism and to understand the enzymes involved followed by pharmacokinetic studies in the appropriately characterized surrogate species. The review will highlight progress made in establishing in vitro-in vivo correlation, predicting human clearance and avoiding costly clinical failures when non-CYP-mediated metabolic pathways are predominant.     

Structural Elucidation of Metabolites of Synthetic Cannabinoid UR-144 by <Emphasis Type="Italic">Cunninghamella elegans</Emphasis> Using Nuclear Magnetic Resonance (NMR) Spectroscopy

The number of new psychoactive substances keeps on rising despite the controlling efforts by law enforcement. Although metabolism of the newly emerging drugs is continuously studied to keep up with the new additions, the exact structures of the metabolites are often not identified due to the insufficient sample quantities for techniques such as nuclear magnetic resonance (NMR) spectroscopy. The aim of the study was to characterise several metabolites of the synthetic cannabinoid (1-pentyl-1H-indol-3-yl) (2,2,3,3-tetramethylcyclopropyl) methanone (UR-144) by NMR spectroscopy after the incubation with the fungus Cunninghamella elegans. UR-144 was incubated with C. elegans for 72 h, and the resulting metabolites were chromatographically separated. Six fractions were collected and analysed by NMR spectroscopy. UR-144 was also incubated with human liver microsomes (HLM), and the liquid chromatography-high resolution mass spectrometry analysis was performed on the HLM metabolites with the characterised fungal metabolites as reference standards. Ten metabolites were characterised by NMR analysis including dihydroxy metabolites, carboxy and hydroxy metabolites, a hydroxy and ketone metabolite, and a carboxy and ketone metabolite. Of these metabolites, dihydroxy metabolite, carboxy and hydroxy metabolites, and a hydroxy and ketone metabolite were identified in HLM incubation. The results indicate that the fungus is capable of producing human-relevant metabolites including the exact isomers. The capacity of the fungus C. elegans to allow for NMR structural characterisation by enabling production of large amounts of metabolites makes it an ideal model to complement metabolism studies.     

Succinate dehydrogenase activity regulates PCB3-quinone-induced metabolic oxidative stress and toxicity in HaCaT human keratinocytes

Polychlorinated biphenyls (PCBs) and their metabolites are environmental pollutants that are known to have adverse health effects. 1-(4-Chlorophenyl)-benzo-2,5-quinone (4-ClBQ), a quinone metabolite of 4-monochlorobiphenyl (PCB3, present in the environment and human blood) is toxic to human skin keratinocytes, and breast and prostate epithelial cells. This study investigates the hypothesis that 4-ClBQ-induced metabolic oxidative stress regulates toxicity in human keratinocytes. Results from Seahorse XF96 Analyzer showed that the 4-ClBQ treatment increased extracellular acidification rate, proton production rate, oxygen consumption rate and ATP content, indicative of metabolic oxidative stress. Results from a q-RT-PCR assay showed significant increases in the mRNA levels of hexokinase 2 (hk2), pyruvate kinase M2 (pkm2) and glucose-6-phosphate dehydrogenase (g6pd), and decreases in the mRNA levels of succinate dehydrogenase (complex II) subunit C and D (sdhc and sdhd). Pharmacological inhibition of G6PD-activity enhanced the toxicity of 4-ClBQ, suggesting that the protective function of the pentose phosphate pathway is functional in 4-ClBQ-treated cells. The decrease in sdhc and sdhd expression was associated with a significant decrease in complex II activity and increase in mitochondrial levels of ROS. Overexpression of sdhc and sdhd suppressed 4-ClBQ-induced inhibition of complex II activity, increase in mitochondrial levels of ROS, and toxicity. These results suggest that the 4-ClBQ treatment induces metabolic oxidative stress in HaCaT cells, and while the protective function of the pentose phosphate pathway is active, inhibition of complex II activity sensitizes HaCaT cells to 4-ClBQ-induced toxicity.     

Metabolic fingerprinting of different populations of <Emphasis Type="Italic">Phyllanthus niruri</Emphasis> L. from Punjab using electrospray ionization mass spectrometry (ESI–MS)

There is growing interest of healthcare and food industry in ingredients of plant origin as they are potent sources of antioxidant, anti-inflammatory, antimicrobial and anticancer agents. In the present work different extracts of Phyllanthus niruri L. from various regions of Punjab were screened for their phenolic profiles and antioxidant properties. Crude extracts obtained by solid–liquid extraction with different solvents were tested for total anthocyanins, flavonoids, phenolic content, and free radical scavenging activity. Out of all the solvents used, methanol was regarded as best to be used for soxhlet extraction of plant metabolites, as it provided highest phenolic, flavonoid, antioxidant, and anthocyanin contents. Similarly, ESI–MS was employed to obtain mass profiles of phenolic and other metabolites present in various P. niruri populations. Out of 72 compounds detected, 51 are reported for the first time in P. niruri L. Similarly, different populations of P. niruri were discriminated through metabolic fingerprinting using ESI–MS.     

Identifying Metabolites of Meclonazepam by High-Resolution Mass Spectrometry Using Human Liver Microsomes,Hepatocytes, a Mouse Model,and Authentic Urine Samples

Meclonazepam is a benzodiazepine patented in 1977 to treat parasitic worms, which recently appeared as a designer benzodiazepine and drug of abuse. The aim of this study was to identify metabolites suitable as biomarkers of drug intake in urine using high-resolution mass spectrometry, authentic urine samples, and different model systems including human liver microsomes, cryopreserved hepatocytes, and a mice model. The main metabolites of meclonazepam found in human urine were amino-meclonazepam and acetamido-meclonazepam; also, minor peaks for meclonazepam were observed in three of four urine samples. These observations are consistent with meclonazepam having a metabolism similar to that of other nitro containing benzodiazepines such as clonazepam, flunitrazepam, and nitrazepam. Both metabolites were produced by the hepatocytes and in the mice model, but the human liver microsomes were only capable of producing minor amounts of the amino metabolite. However, under nitrogen, the amount of amino-meclonazepam produced increased 140 times. This study comprehensively elucidated meclonazepam metabolism and also illustrates that careful selection of in vitro model systems for drug metabolism is needed, always taking into account the expected metabolism of the tested drug.     

Pentylindole/Pentylindazole Synthetic Cannabinoids and Their 5-Fluoro Analogs Produce Different Primary Metabolites: Metabolite Profiling for AB-PINACA and 5F-AB-PINACA

Whereas non-fluoropentylindole/indazole synthetic cannabinoids appear to be metabolized preferably at the pentyl chain though without clear preference for one specific position, their 5-fluoro analogs’ major metabolites usually are 5-hydroxypentyl and pentanoic acid metabolites. We determined metabolic stability and metabolites of N-(1-amino-3-methyl-1-oxobutan-2-yl)-1-pentyl-1H-indazole-3-carboxamide (AB-PINACA) and 5-fluoro-AB-PINACA (5F-AB-PINACA), two new synthetic cannabinoids, and investigated if results were similar. In silico prediction was performed with MetaSite (Molecular Discovery). For metabolic stability, 1 μmol/L of each compound was incubated with human liver microsomes for up to 1 h, and for metabolite profiling, 10 μmol/L was incubated with pooled human hepatocytes for up to 3 h. Also, authentic urine specimens from AB-PINACA cases were hydrolyzed and extracted. All samples were analyzed by liquid chromatography high-resolution mass spectrometry on a TripleTOF 5600+ (AB SCIEX) with gradient elution (0.1% formic acid in water and acetonitrile). High-resolution full-scan mass spectrometry (MS) and information-dependent acquisition MS/MS data were analyzed with MetabolitePilot (AB SCIEX) using different data processing algorithms. Both drugs had intermediate clearance. We identified 23 AB-PINACA metabolites, generated by carboxamide hydrolysis, hydroxylation, ketone formation, carboxylation, epoxide formation with subsequent hydrolysis, or reaction combinations. We identified 18 5F-AB-PINACA metabolites, generated by the same biotransformations and oxidative defluorination producing 5-hydroxypentyl and pentanoic acid metabolites shared with AB-PINACA. Authentic urine specimens documented presence of these metabolites. AB-PINACA and 5F-AB-PINACA produced suggested metabolite patterns. AB-PINACA was predominantly hydrolyzed to AB-PINACA carboxylic acid, carbonyl-AB-PINACA, and hydroxypentyl AB-PINACA, likely in 4-position. The most intense 5F-AB-PINACA metabolites were AB-PINACA pentanoic acid and 5-hydroxypentyl-AB-PINACA.

Electronic supplementary material

The online version of this article (doi:10.1208/s12248-015-9721-0) contains supplementary material, which is available to authorized users.KEY WORDS: 5-fluoro-AB-PINACA, AB-PINACA, in silico prediction, metabolism, synthetic cannabinoids     

Development of a column-switching LC-MS/MS method of tramadol and its metabolites in hair and application to a pharmacogenetic study

Hair is a valuable specimen for monitoring long-term drug use. Tramadol is an effective opioid analgesic but is associated with risks such as drug dependence and unexpected toxicity arising from genetic differences in metabolism. However, few studies have been performed on the distribution of tramadol and its metabolites in hair. In the present study, a column-switching LC-MS/MS method was developed and fully validated for the simultaneous determination of tramadol and its phase I and II metabolites in hair. Furthermore, the distribution of tramadol and its metabolites in hair was investigated in a pharmacogenetic study. Tramadol and its metabolites were extracted from hair using methanol and injected onto LC-MS/MS. The validation results of selectivity, matrix effect, linearity, precision and accuracy were satisfactory. The (mean) concentrations of O-desmethyltramadol (ODMT) and N,O-didesmethyltramadol (NODMT) in the CYP2D6*10/*10 and CYP2D6*5/*5 groups were lower than those in the CYP2D6*wt/*wt group, while the (mean) concentrations of N-desmethyltramadol (NDMT) were higher. Moreover, the ratios of ODMT/tramadol, NDMT/tramadol and NODMT/NDMT were well correlated with the CYP2D6 genotypes. The developed method was successfully applied to the clinical study, which demonstrated that the concentrations of a drug and its metabolites in hair were dependent on the polymorphism of its metabolizing enzyme.     

Effect of the <Emphasis Type="Italic">CYP2D6*10</Emphasis> allele on the pharmacokinetics of clomiphene and its active metabolites

Clomiphene citrate, a selective estrogen receptor modulator, is metabolized into its 4-hydroxylated active metabolites, primarily by CYP2D6. In this study, we investigated the effects of the most common CYP2D6 variant allele in Asians, CYP2D6*10, on the pharmacokinetics of clomiphene and its two active metabolites (4-OH-CLO and 4-OH-DE-CLO) in healthy Korean subjects. A single 50-mg oral dose of clomiphene citrate was given to 22 Korean subjects divided into three genotype groups according to CYP2D6 genotypes, CYP2D6*wt/*wt (n = 8; *wt = *1 or *2), CYP2D6*wt/*10 (n = 8) and CYP2D6*10/*10 (n = 6). Concentrations of clomiphene and its metabolites were determined using a validated HPLC–MS/MS analytical method in plasma samples collected up to 168 h after the drug intake. There was a significant difference only in the C_max of clomiphene between three CYP2D6 genotype groups (p < 0.05). Paradoxically, the elimination half-life (t_1/2) and AUC of both active metabolites were all significantly increased in the CYP2D6*10 homozygous carriers, compared with other genotype groups (all p < 0.001). The AUC_inf of corrected clomiphene active moiety in CYP2D6*10/*10 subjects was 2.95- and 2.05-fold higher than that of CYP2D6*wt/*wt and *wt/*10 genotype groups, respectively (both p < 0.001). Along with the partial impacts on the biotransformation of clomiphene and its metabolites by CYP2D6 genetic polymorphism, further studies on the effects of other CYP enzymes in a multiple-dosing condition can provide more definite evidence for the inter-individual variabilities in clomiphene pharmacokinetics and/or drug response.     

Evaluation of the Utility of Chimeric Mice with Humanized Livers for the Characterization and Profiling of the Metabolites of a Selective Inhibitor (YM543) of the Sodium-Glucose Cotransporter 2

Purpose

YM543 is a novel selective inhibitor of the sodium-glucose cotransporter 2. The objectives of the current study were to evaluate the utility of mice with humanized livers to predict human drug metabolites using YM543 as a case example.

Methods

Metabolites of YM543 generated in humans and experimental animals including chimeric mice with humanized liver, PXB mice, were analyzed via liquid chromatography-mass spectrometry, liquid chromatography-radiometric detector or nuclear magnetic resonance spectrometer.

Results

After oral administration of YM543, metabolites M1–M5 were detected in human plasma and urine. M2–M4 were detected in at least one species while M1 was not generated by experimental animals or in vitro systems. In the metabolite profiling in PXB mice, M1 was detected in both plasma and urine samples.

Conclusions

Metabolite profile of YM543 in PXB mice and humans was closely resemble. and the human specific metabolite was detected in the model mice. The human specific metabolite, M1, was difficult to know in advance to clinical study. The ability to predict the human metabolite profile including presence of human specific metabolites using PXB mice will likely facilitate development of new drug candidates for human use.

     

Development of a linear dual column HPLC–MS/MS method and clinical genetic evaluation for tramadol and its phase I and II metabolites in oral fluid

Tramadol is a centrally acting synthetic opioid analgesic and has received special attention due to its abuse potential and unexpected responses induced by CYP2D6 polymorphism. Oral fluid is an advantageous biofluid for drug analysis due to non-invasive sampling and high correlation of drug concentrations with plasma. However, few studies have been performed on distribution of tramadol and its metabolites in oral fluid. In the present study, a linear dual column HPLC–MS/MS method was developed and fully validated for the simultaneous determination of tramadol and its phase I [O-desmethyltramadol (ODMT), N-desmethyltramadol (NDMT) and N,O-didesmethyltramadol (NODMT)] and II metabolites in oral fluid. Furthermore, the distribution of tramadol and its metabolites, in relation to CYP2D6 genetic variations, in oral fluid was investigated following a clinical study including 23 subjects with CYP2D6*wt/*wt, CYP2D6*10/*10 or CYP2D6*5/*5. The validation results of selectivity, matrix effect, linearity, precision and accuracy were satisfactory. Pharmacokinetic parameters, such as C_ss,max and AUC_0–τ of tramadol, NDMT and NODMT, in the CYP2D6*10/*10 group were significantly higher than those in the CYP2D6*wt/*wt group. Moreover, the ratios of ODMT/tramadol, NDMT/tramadol and NODMT/NDMT correlated well with the CYP2D6 genotypes. We demonstrated that oral fluid is a promising biofluid for pharmacokinetic evaluation in relation to genetic variations.     

Metabolic characterization of AH‐7921, a synthetic opioid designer drug: in vitro metabolic stability assessment and metabolite identification,evaluation of in silico prediction,and in vivo confirmation

AH‐7921 (3,4‐dichloro‐N‐[(1‐dimethylamino)cyclohexylmethyl]benzamide) is a new synthetic opioid and has led to multiple non‐fatal and fatal intoxications. To comprehensively study AH‐7921 metabolism, we assessed human liver microsome (HLM) metabolic stability, determined AH‐7921's metabolic profile after human hepatocytes incubation, confirmed our findings in a urine case specimen, and compared results to in silico predictions. For metabolic stability, 1 µmol/L AH‐7921 was incubated with HLM for up to 1 h; for metabolite profiling, 10 µmol/L was incubated with pooled human hepatocytes for up to 3 h. Hepatocyte samples were analyzed by liquid chromatography quadrupole/time‐of‐flight high‐resolution mass spectrometry (MS). High‐resolution full scan MS and information‐dependent acquisition MS/MS data were analyzed with MetabolitePilot? (SCIEX) using multiple data processing algorithms. The presence of AH‐7921 and metabolites was confirmed in the urine case specimen. In silico prediction of metabolite structures was performed with MetaSite? (Molecular Discovery). AH‐7921 in vitro half‐life was 13.5 ± 0.4 min. We identified 12 AH‐7921 metabolites after hepatocyte incubation, predominantly generated by demethylation, less dominantly by hydroxylation, and combinations of different biotransformations. Eleven of 12 metabolites identified in hepatocytes were found in the urine case specimen. One metabolite, proposed to be di‐demethylated, N‐hydroxylated and glucuronidated, eluted after AH‐7921 and was the most abundant metabolite in non‐hydrolyzed urine. MetaSite? correctly predicted the two most abundant metabolites and the majority of observed biotransformations. The two most dominant metabolites after hepatocyte incubation (also identified in the urine case specimen) were desmethyl and di‐desmethyl AH‐7921. Together with the glucuronidated metabolites, these are likely suitable analytical targets for documenting AH‐7921 intake. Copyright © 2015 John Wiley & Sons, Ltd.     

The association of clopidogrel and 2-oxo-clopidogrel plasma levels and the 40 months clinical outcome after primary PCI

Background A significant number of ischemic events occur even when adhering to dual antiplatelet therapy including aspirin and clopidogrel. Objectives The aim of our study was to determine predictors of long-term patient clinical outcome, among variables such as prodrug clopidogrel and intermediary metabolite 2-oxoclopidogrel concentrations, as well as patients’ clinical characteristics. Setting Department for the Treatment of Acute Coronary Syndrome in tertiary teaching hospital, Serbia. Methods This study enrolled 88 consecutive patients with first STEMI, treated with primary PCI, within 6 h of the chest pain onset and followed them 40 months. On the third day of hospitalization, blood samples were collected from each patient to measure clopidogrel and its metabolite 2-oxo-clopidogrel concentration by UHPLC-DAD-MS method. Main outcome measure Mortality from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke or hospitalization for urgent myocardial revascularization or heart failure. Results The composite clinical outcome of cardiovascular mortality, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for urgent myocardial revascularization or heart failure, was registered in 31 patients (35.2%) during the 40-month follow-up. Lower clopidogrel (p?<?0.05) and dose-adjusted clopidogrel concentrations (p?<?0.05) were associated with the higher incidence of composite outcome events. Their low plasma concentrations may be predicted by fentanyl administration (p?<?0.001) and creatinine clearance (p?<?0.01). The decrease in dose-adjusted clopidogrel unit for each ng/ml/mg increases the risk 21.7 times (p?<?0.05). Conclusion Clopidogrel dose-adjusted plasma concentration in STEMI patients, as well as multivessel coronary artery disease, showed significance in predicting an unfavorable composite clinical outcome after 40-month follow-up.     

Effects of <Emphasis Type="Italic">CYP2C9</Emphasis> genetic polymorphisms on the pharmacokinetics of celecoxib and its carboxylic acid metabolite

Celecoxib, a selective cyclooxygenase (COX)-2 inhibitor, is used for the treatment of rheumatoid arthritis and osteoarthritis. The predominant hepatic metabolism of celecoxib to celecoxib carboxylic acid (CCA) is mediated mainly by CYP2C9. We investigated the effects of the major CYP2C9 genetic variants in Asian populations, CYP2C9*3 and CYP2C9*13, on the pharmacokinetics of celecoxib and its carboxylic acid metabolite in healthy Korean subjects. A single 200-mg oral dose of celecoxib was given to 52 Korean subjects with different CYP2C9 genotypes: CYP2C9EM (n = 26; CYP2C9*1/*1), CYP2C9IM (n = 24; CYP2C9*1/*3 and *1/*13), and CYP2C9PM (n = 2; CYP2C9*3/*3). Celecoxib and CCA concentrations in plasma samples collected up to 48 or 96 h after drug intake were determined by HPLC–MS/MS. The mean area under the plasma concentration–time curve (AUC_0–∞) of celecoxib was increased 1.63-fold (P < 0.001), and the apparent oral clearance (CL/F) of celecoxib was decreased by 39.6% in the CYP2C9IM genotype group compared with that of CYP2C9EM (P < 0.001). The overall pharmacokinetic parameters for celecoxib in CYP2C9*1/*13 subjects were similar to those in CYP2C9*1/*3 subjects. Two subjects with CYP2C9PM genotype both showed markedly higher AUC_0–∞, prolonged half-life, and lower CL/F for celecoxib than did subjects with CYP2C9EM and IM genotypes. CYP2C9*3 and CYP2C9*13 variant alleles significantly affected the plasma concentration of celecoxib.     

Structure–activity relationship study of secondary metabolites from <Emphasis Type="Italic">Mesua beccariana</Emphasis>, <Emphasis Type="Italic">Mesua ferrea</Emphasis> and <Emphasis Type="Italic">Mesua congestiflora</Emphasis> for anti-cholinesterase activity

Our search for potential anti-acetylcholinesterase (AChE) inhibitors for treatment of Alzheimer’s disease has led to the discovery of two bioactive compounds, α-mangostin (11) and congestiflorone acetate (13). This discovery was achieved from a preliminary screening of the anti-AChE activity on the extracts of three Mesua species namely M. ferrea, M. beccariana and M. congestiflora using Ellman’s method. The pure metabolites, 1–12 which were isolated from the Mesua species, along with a synthetic derivative, compound 13 were then evaluated for their activities in order to identify the compounds that correspond to the enzyme inhibitory activities. Compounds 11 and 13 were found to give significant anti-AChE activities with IC₅₀ values of 17.51 and 20.25 µM.     

Expression,Purification and Characterization of GMZ2’.10C,a Complex Disulphide-Bonded Fusion Protein Vaccine Candidate against the Asexual and Sexual Life-Stages of the Malaria-Causing <Emphasis Type="BoldItalic">Plasmodium falciparum</Emphasis> Parasite

Purpose

Production and characterization of a chimeric fusion protein (GMZ2’.10C) which combines epitopes of key malaria parasite antigens: glutamate-rich protein (GLURP), merozoite surface protein 3 (MSP3), and the highly disulphide bonded Pfs48/45 (10C). GMZ2’.10C is a potential candidate for a multi-stage malaria vaccine that targets both transmission and asexual life-cycle stages of the parasite.

Methods

GMZ2’.10C was produced in Lactococcus lactis and purified using either an immunoaffinity purification (IP) or a conventional purification (CP) method. Protein purity and stability was analysed by RP-HPLC, SEC-HPLC, 2-site ELISA, gel-electrophoresis and Western blotting. Structural characterization (mass analysis, peptide mapping and cysteine connectivity mapping) was performed by LC-MS/MS.

Results

CP-GMZ2’.10C resulted in similar purity, yield, structure and stability as compared to IP-GMZ2’.10C. CP-GMZ2’.10C and IP-GMZ2’.10C both elicited a high titer of transmission blocking (TB) antibodies in rodents. The intricate disulphide-bond connectivity of C-terminus Pfs48/45 was analysed by tandem mass spectrometry and was established for GMZ2’.10C and two reference fusion proteins encompassing similar parts of Pfs48/45.

Conclusion

GMZ2’.10C, combining GMZ2’ and correctly-folded Pfs48/45 can be produced by the Lactoccus lactis P170 based expression system in purity and quality for pharmaceutical development and elicit high level of TB antibodies. The cysteine connectivity for the 10C region of Pfs48/45 was revealed experimentally, providing an important guideline for employing the Pfs48/45 antigen in vaccine design.

     

Model-based approaches for ivabradine development in paediatric population,part II: PK and PK/PD assessment

The objectives of this work were first to describe the pharmacokinetic (PK) of ivabradine and its active metabolite in a paediatric patient population after repeated oral administration of ivabradine using a population PK approach, and secondly to assess whether the blood/plasma ratio and the pharmacokinetic/pharmacodynamic (PK/PD) relationship are preserved in the paediatric population in comparison to adult. PK data for 70 patients were obtained after blood sampling using dried blood spot and one plasma sample in order to assess the relationship between blood and plasma concentration. In order to describe ivabradine and its metabolite blood concentrations in children, a joint population PK model was developed taking into account weight & age effects on PK parameters. Plasma PK exposure parameters were calculated in children using plasma PK profiles. In order to assess the PK/PD relationship in children, an adult PK/PD model was used. The relationship between blood and plasma concentrations was described using linear mixed effect models. Two and one—compartment models best described parent and metabolite dispositions. Weight effects were fixed to the allometric values of ¾ on clearance (CL) and 1 on volume. A maturation function was added on metabolite formation clearance (CL _PM ) reflecting enzyme maturation. Plasma exposure comparison indicated that higher dose/kg were necessary to achieve a similar exposure between younger and older children. No differences between age classes were observed in terms of range of exposure at the maintenance dose. The PK/PD relationship in adult patients is conserved in children.     

Knowledge,attitudes, practices,and barriers related to research utilization: a survey among pharmacists in Malaysia

Background Research utilization is part of evidence-based practice referring to the process of reviewing and critiquing scientific research and applying the findings to one’s own clinical practice. Many studies on research utilization have been conducted with doctors and nurses, but to our knowledge, none have been investigated amongst pharmacists. Objective To assess research utilization and its barriers among pharmacists and identify potential influencing factors. Setting Malaysia. Methods This cross-sectional survey was administered online and by mail to a convenient sample of pharmacists working in hospitals, health clinics, and retail pharmacies in rural and urban areas. Main outcome measure Pharmacists’ research utilization knowledge, attitudes, and practices. Results Six hundred surveys were mailed to potential respondents, and 466 were returned (77.7% response rate). Twenty-eight respondents completed the survey online. The respondents’ research utilization knowledge, attitudes, and practices were found to be moderate. Research utilization was associated with respondents’ knowledge and attitude scores (P < 0.001). When factors related to research utilization were modelled, higher educational level was associated with higher level of research utilization (P < 0.001) while less involvement in journal clubs, more years of service (3–7 years and more than 7 years) were associated with low and moderate research utilization, respectively. The main reported barrier to research utilization was lack of sufficient authority to change patient care procedures. Conclusion Pharmacists’ research utilization knowledge, attitudes, and practices can be improved by encouraging pharmacists to pursue higher degrees, promoting active participation in institutions’ journal clubs, and introducing senior clinical pharmacist specialization.     

Evaluation of the effect of acetazolamide versus mannitol on cisplatin-induced nephrotoxicity,a pilot study

Background Cisplatin-induced nephrotoxicity still occurs despite the intensive hydration approach adapted to prevent its occurrence. Objective Evaluation of the effect of acetazolamide (ACTZ) on minimizing cisplatin-induced nephrotoxicity compared to mannitol when added to hydration regimen. Setting Nasser Institute Cancer Center (NICC), Cairo, Egypt. Method A total of 35 patients planned to receive cisplatin were divided into two groups: 20 patients received mannitol and 15 patients received ACTZ. Both groups received standard hydration measures as well for prevention of cisplatin-induced nephrotoxicity. Main outcome measure Patients’ kidney function was assessed using serum creatinine, creatinine clearance and blood urea nitrogen. Kidney injury was assessed using RIFLE criteria. Patients’ liver function tests and hematological parameters were also monitored. Results Patients in the mannitol group showed higher risk of developing kidney injury (30%) whereas those in the ACTZ group showed lower risk (8.9%), relative risk (RR) 0.269, 95% CI 0.108–0.815. No statistically significant difference occurred between the two groups concerning liver function tests or hematological parameters. Conclusion Use of ACTZ in addition to intensive hydration may have more beneficial effect on minimizing cisplatin-induced nephrotoxicity compared to mannitol plus intensive hydration approach. A large multicenter randomized clinical trials is recommended to confirm study results and to assess effect of ACTZ on tumor response.