Loeckie Zwart - Academia.edu (original) (raw)
Papers by Loeckie Zwart
Journal of Chromatography B: Biomedical Sciences and Applications, 1997
One of the major processes that occur as a result of radical-induced oxidative stress is lipid pe... more One of the major processes that occur as a result of radical-induced oxidative stress is lipid peroxidation (LPO). Degradation of lipid peroxides results in various products, including a variety of carbonyl compounds. In the present study eight different lipid degradation products, i.e., formaldehyde, acetaldehyde, acetone, propanal, butanal, pentanal, hexanal and malondialdehyde were identified and measured simultaneously and quantitatively in rat urine after derivatization with O-(2,3,4,5,6-pentafluorbenzyl)hydroxylamine hydrochloride, extraction with heptane and using gas chromatography-electron-capture detection (GC-ECD). The identity of the respective oximes in urine was confirmed by gas chromatography-negative ion chemical ionization mass spectrometry (GC-NCI-MS). Simultaneously measured standard curves were linear for all oxime-products and the detection limits were between 39.0 +/- 5.3 (n=9) and 500 +/- 23 (n=9) fmol per microl injected sample. Recoveries of all products from urine or water were 73.0 +/- 5.2% and higher. In urine of CCl4-treated rats an increase in all eight lipid degradation products in urine was found 24 h following exposure. ACON showed the most distinct increase, followed by PROPA, BUTA and MDA. It is concluded that the rapid, selective and sensitive analytical method based on GC-ECD presented here is well suited for routine measurement of eight different lipid degradation products. These products appear to be useful as non-invasive biomarkers for in vivo oxidative stress induced in rats by CCl4.
Antimicrobial Agents and Chemotherapy, 2010
Human respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in... more Human respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants, young children, elderly persons, and severely immunocompromised patients. Effective postinfection treatments are not widely available, and currently there is no approved vaccine. TMC353121 is a potent RSV fusion inhibitor in vitro, and its ability to reduce viral loads in vivo was demonstrated in cotton rats following prophylactic intravenous administration. Here, the pharmacokinetics of TMC353121 in the cotton rat, which is semipermissive for RSV replication, were further explored to build a pharmacokinetic-pharmacodynamic (PK-PD) model and to estimate the plasma drug levels needed for significant antiviral efficacy. TMC353121 reduced the viral titers in bronchoalveolar lavage fluid in a dose-dependent manner after a single subcutaneous administration and intranasal RSV inoculation 24 h after compound administration. The viral titer reduction and plasma TMC353121 concentration at the time of RSV inoculation were well described using a simple E max model with a maximal viral titer reduction (E max ) of 1.5 log 10 . The plasma drug level required to achieve 50% of the E max (200 ng/ml) was much higher than the 50% inhibitory concentration observed in vitro in HeLaM cells (0.07 ng/ml). In conclusion, this simple PK-PD approach may be useful in predicting efficacious exposure levels for future RSV inhibitors.
Antimicrobial agents and chemotherapy, 2010
Human respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in... more Human respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants, young children, elderly persons, and severely immunocompromised patients. Effective postinfection treatments are not widely available, and currently there is no approved vaccine. TMC353121 is a potent RSV fusion inhibitor in vitro, and its ability to reduce viral loads in vivo was demonstrated in cotton rats following prophylactic intravenous administration. Here, the pharmacokinetics of TMC353121 in the cotton rat, which is semipermissive for RSV replication, were further explored to build a pharmacokinetic-pharmacodynamic (PK-PD) model and to estimate the plasma drug levels needed for significant antiviral efficacy. TMC353121 reduced the viral titers in bronchoalveolar lavage fluid in a dose-dependent manner after a single subcutaneous administration and intranasal RSV inoculation 24 h after compound administration. The viral titer reduction and plasma TMC353121 concentration...
The American Journal of Forensic Medicine and Pathology, 2012
Postmortem redistribution of fentanyl in the rabbit was investigated after application of the 50-... more Postmortem redistribution of fentanyl in the rabbit was investigated after application of the 50-μg/h Durogesic pain patch. Patches were applied for 48 hours. Two cycles of patch administration were used before characterization of the postmortem redistribution. Fentanyl showed marked redistribution into the femoral and pulmonary veins of the rabbit through 48 hours after the animals were humanely killed and the pain patches removed. The plasma concentration of 2.34 ng/mL in the femoral blood before killing the animals increased 5.6-fold by 48 hours after patch removal to 13.2 ng/mL. This postmortem concentration is approximately 3-fold the C(max) determined during antemortem pharmacokinetic analysis, 4 ng/mL, which was achieved 24 hours after the application of the second 50-μg/h Durogesic pain patch. After blood sampling for 48 hours after animal termination with patch removal compared with sampling for 48 hours from animals not terminated and with patch removal, the exposure ratios in the terminated animals were approximately 30-fold, indicating that between the postmortem redistribution of fentanyl and the cessation of hepatic clearance of fentanyl in the rabbit, the postmortem redistribution of fentanyl leads to an elevated measures of postmortem blood concentrations relative to antemortem blood concentrations.
Based on ibrutinib pharmacokinetics and potential sensitivity towards CYP3A4-mediated DDI, a phys... more Based on ibrutinib pharmacokinetics and potential sensitivity towards CYP3A4-mediated DDI, a physiologically-based pharmacokinetic approach was developed to mechanistically describe DDI with various CYP3A4 perpetrators in healthy men under fasting conditions. These models were verified using clinical data for ketoconazole (strong CYP3A4 inhibitor) and used to prospectively predict and confirm the inducing effect of rifampin (strong CYP3A4 inducer); DDIs with mild (fluvoxamine, azithromycin) and moderate inhibitors (diltiazem, voriconazole, clarithromycin, itraconazole, erythromycin), and moderate (efavirenz) and strong CYP3A4 inducers (carbamazepine) were also predicted. Ketoconazole increased ibrutinib AUC by 24fold, while rifampin decreased ibrutinib AUC by 10-fold; coadministration of ibrutinib with strong inhibitors or inducers should be avoided. Ibrutinib dose should be reduced to 140 mg (quarter of maximal prescribed dose) when coadministered with moderate CYP3A4 inhibitors so that exposures remain within observed ranges at therapeutic doses. Thus, dose recommendations for CYP3A4 perpetrator use during ibrutinib treatment were developed and approved for labelling.
Archives of environmental contamination and toxicology, 2004
Soil ingestion is an important pathway of exposure for many nonvolatile contaminants for man and ... more Soil ingestion is an important pathway of exposure for many nonvolatile contaminants for man and in particular for children. A fraction of the ingested contaminant may not dissociate from the soil particles during digestion in the gastrointestinal tract, and is thus not available for transport across the intestinal epithelium. In order to estimate the contaminant fraction that is mobilized from soil, i.e., the bioaccessible fraction, several in vitro digestion models have been developed. The currently existing digestion models display many differences. One aspect that may affect bioaccessibility and may induce differences between digestion models is the bile that is used. Often freeze-dried bile of animal origin is preferred to purified bile salts. However, also the animal origin of bile may give rise to differences in bioaccessibility because bile composition appears to be species dependent. In the present study, we compared the bioaccessibility of benzo[a]pyrene, arsenic, cadmium,...
Journal of Chromatography B: Biomedical Sciences and Applications, 1997
One of the major processes that occur as a result of radical-induced oxidative stress is lipid pe... more One of the major processes that occur as a result of radical-induced oxidative stress is lipid peroxidation (LPO). Degradation of lipid peroxides results in various products, including a variety of carbonyl compounds. In the present study eight different lipid degradation products, i.e., formaldehyde, acetaldehyde, acetone, propanal, butanal, pentanal, hexanal and malondialdehyde were identified and measured simultaneously and quantitatively in rat urine after derivatization with O-(2,3,4,5,6-pentafluorbenzyl)hydroxylamine hydrochloride, extraction with heptane and using gas chromatography-electron-capture detection (GC-ECD). The identity of the respective oximes in urine was confirmed by gas chromatography-negative ion chemical ionization mass spectrometry (GC-NCI-MS). Simultaneously measured standard curves were linear for all oxime-products and the detection limits were between 39.0 +/- 5.3 (n=9) and 500 +/- 23 (n=9) fmol per microl injected sample. Recoveries of all products from urine or water were 73.0 +/- 5.2% and higher. In urine of CCl4-treated rats an increase in all eight lipid degradation products in urine was found 24 h following exposure. ACON showed the most distinct increase, followed by PROPA, BUTA and MDA. It is concluded that the rapid, selective and sensitive analytical method based on GC-ECD presented here is well suited for routine measurement of eight different lipid degradation products. These products appear to be useful as non-invasive biomarkers for in vivo oxidative stress induced in rats by CCl4.
Reproductive Toxicology, 2008
Knowledge of the ontogeny of the various systems involved in distribution and elimination of drug... more Knowledge of the ontogeny of the various systems involved in distribution and elimination of drugs is important for adequate interpretation of the findings during safety studies in juvenile animals.
Xenobiotica, 1996
1. 4-Hydroxy-2,3-nonenal (HNE) is an end product of lipid peroxidation (LPO) and a well known cyt... more 1. 4-Hydroxy-2,3-nonenal (HNE) is an end product of lipid peroxidation (LPO) and a well known cytotoxic aldehyde that exhibits a variety of biological effects. In this study the in vivo disposition and covalent binding of i.p. administered [2-3H]HNE was examined in the rat. 2. It was found that several metabolites of [2-3H]HNE are excreted in urine among which at least four mercapturic acids. 1,4-Dihydroxynonane mercapturic acid (DHN-MA) appeared to be the most abundant mercapturic acid excreted in urine (3.5% of the dose) and the excretion of the other three mercapturic acids amounted to 2% of the dose. 3. Within 48 h following i.p. administration of 5 or 25 mumol/kg bodyweight [2-3H]HNE (specific activity 4 microCi/mumol) about 25% of the radioactivity was excreted in urine, whereas 18% of the radioactivity appeared in the faeces. 4. After 48 h, 7% of the radioactivity was still present in the liver and 0.2% in other organs, but this radioactivity appeared to not to be covalently bound to cellular macromolecules. It was found that only 0.13% of the radioactivity was covalently bound in the liver and even less in other organs.
Toxicology and Applied Pharmacology, 1998
Carbon tetrachloride (CCl 4 ) is a model compound for inducing free radical damage in liver. In t... more Carbon tetrachloride (CCl 4 ) is a model compound for inducing free radical damage in liver. In this study 10 biomarkers in rats treated ip with three different single doses of CCl 4 (0.25, 0.50, and 1.00 ml/kg body wt) were measured dose and time dependently and compared to evaluate these urinary products as noninvasive biomarkers for radical damage. Eight degradation products of lipid peroxides, namely, formaldehyde, acetaldehyde, acetone, propanal, butanal, pentanal, hexanal, and malondialdehyde (MDA), 8-hydroxy-2-deoxyguanosine (8-OH-dG) and coproporphyrin III were measured in this study. As general measures of toxicity, several clinical chemical parameters (n ؍ 12) and histopathological damage were determined. A dose-dependent increase in both the clinical parameters and the lipid degradation products was found. Increases in lipid degradation products were statistically significant at doses of 0.5 and 1 ml/kg CCl 4 . An increase in these products was already found in the first 12 h after exposure. At the lowest dose, 0.25 ml/kg CCl 4 , acetaldehyde and propanal already showed a statistically significant increase as well. No change in the urinary levels of 8-OH-dG could be found in this study and a decrease in the urinary excretion of coproporphyrin III was found. It is concluded that 8-OH-dG and coproporphyrin III are not useful biomarkers for radical damage induced by CCl 4 . Lipid degradation products, however, are promising noninvasive biomarkers for in vivo radical damage, although the precise specificity of these biomarkers for damage induced by radicals needs to be further investigated.
Toxicological Sciences, 1998
There is an increasing need for biomarkers of oxidative stress in animals and man. In this study,... more There is an increasing need for biomarkers of oxidative stress in animals and man. In this study, we have evaluated in the rat the utility of various endogenous products that are excreted in urine as potential noninvasive biomarkers of oxidative stress in the kidney. Renal oxidative damage was induced by daily ip injections of ferric nitrilotriacetate (Fe-NTA) for a period of 13 days. The daily dose of Fe-NTA was increased during the experiment from 6 to 40 mg Fe/kg body wt. The levels of 8-hydroxy-2-deoxyguanosine (8-OHdG), coproporphyrin III (COPRO III), seven aldehydes, and acetone were determined in fractionated urine samples and compared with commonly used urinary and plasma clinical chemical parameters for toxicity. The parameters that showed the earliest increase were acetaldehyde (ACET), propanal (PROPA), and COPRO III. Their increase was significantly earlier than that of classical clinical chemical parameters indicative of renal damage such as urinary concentration of glucose (GLU) and protein (PRT), and N-acetyl--D-glucosaminidase (NAG) activity. The excretion of 8-OHdG was increased only after administration of the highest dose of Fe-NTA. Urinary excretion of acetone, formaldehyde (FOR), butanal (BUTA), pentanal (PENTA) hexanal (HEXA), and malondialdehyde (MDA) was also increased; however, their increase occurred only slightly before or simultaneously with that of the urinary clinical chemical parameters. In conclusion, 8-OHdG, acetone, FOR, BUTA, PENTA, HEXA, and MDA may possibly serve as biomarkers for oxidative kidney damage. COPRO III, ACET, and PROPA might even be used as biomarkers of production of reactive oxygen species at an early stage.
Reproductive Toxicology, 2008
With the growing experience in the conduct of juvenile toxicity studies for multiple classes of c... more With the growing experience in the conduct of juvenile toxicity studies for multiple classes of compound, the 'case-by-case' approach has become under much more pressure. Instead, a general screen or 'standard design' is now commonly expected by regulatory authorities with more routine inclusion of neurological and reproductive assessments. Minor modifications or additions can be made to the design to address specific questions according to the class of drug or intended clinical use. This drift from a 'case-by-case' approach to a 'standard design' approach is present within certain reviewing divisions of the FDA, often requesting by default a rodent and non-rodent juvenile animal study. However, juvenile animal studies should be designed thoughtfully to fulfil a purpose based on scientific rationale, with each endpoint carefully considered in terms of practicality and interpretability of data generated. Only when using the appropriate strategy and design may juvenile studies add value by (1) identifying potential safety or pharmacokinetic issues for drugs intended for paediatric use, (2) suggesting additional clinical endpoints and (3) adding new information to the product label. As the knowledge from juvenile animal studies in various species grows, a better understanding of the significance/relevance of findings will be achieved.
Regulatory Toxicology and Pharmacology, 2004
Whether children incur different risks from xenobiotics than adults will depend on the exposure, ... more Whether children incur different risks from xenobiotics than adults will depend on the exposure, biokinetics, and dynamics of compound. In this paper, current knowledge on developmental physiology and possible effects on biokinetics are evaluated and the role of biokinetics in risk assessment both for drugs and chemicals is discussed. It is concluded that most dramatic age-related physiological changes that may affect biokinetics occur in the first 6-12 months of age. The difference in internal exposure between children and adults can generally be predicted from already known developmental physiological differences. However, for risk assessment it will also be necessary to determine whether internal exposure is within the drug's therapeutic window or if it will exceed the NOAEL of a chemical. Furthermore, the effects of internal exposure of potentially harmful compounds on developing organ systems is of utmost importance. However, knowledge on this aspect is very limited. Risk assessment in children could be improved by: (1) application of pediatric PBPK-models in order to gain insight into internal exposure in children, (2) studies in juvenile animals for studying effects on developing systems, and (3) extrapolation of knowledge on the relationship between internal exposure and dynamics for drugs to other chemicals.
Free Radical Biology and Medicine, 1999
Free radical damage is an important factor in many pathological and toxicological processes. Desp... more Free radical damage is an important factor in many pathological and toxicological processes. Despite extensive research efforts in biomarkers in recent years, yielding promising results in experimental animals, there is still a great need for additional research on the applicability of, especially non-invasive, biomarkers of free radical damage in humans. This review gives an overview of the applications in experimental
Environmental Science & Technology, 2002
Soil ingestion can be a major exposure route for humans to many immobile soil contaminants. Expos... more Soil ingestion can be a major exposure route for humans to many immobile soil contaminants. Exposure to soil contaminants can be overestimated if oral bioavailability is not taken into account. Several in vitro digestion models simulating the human gastrointestinal tract have been developed to assess mobilization of contaminants from soil during digestion, i.e., bioaccessibility. Bioaccessibility is a crucial step in controlling the oral bioavailability for soil contaminants. To what extent in vitro determination of bioaccessibility is method dependent has, until now, not been studied. This paper describes a multi-laboratory comparison and evaluation of five in vitro digestion models. Their experimental design and the results of a round robin evaluation of three soils, each contaminated with arsenic, cadmium, and lead, are presented and discussed. A wide range of bioaccessibility values were found for the three soils: for As 6-95%, 1-19%, and 10-59%; for Cd 7-92%, 5-92%, and 6-99%; and for Pb 4-91%, 1-56%, and 3-90%. Bioaccessibility in many cases is less than 50%, indicating that a reduction of bioavailability can have implications for health risk assessment. Although the experimental designs of the different digestion systems are distinct, the main differences in test results of bioaccessibility can be explained on the basis of the applied gastric pH. High values are typically observed for a simple gastric method, which measures bioaccessibility in the gastric compartment at low pHs of 1.5. Other methods that also apply a low gastric pH, and include intestinal conditions, produce lower bioaccessibility values. The lowest bioaccessibility values are observed for a gastrointestinal method which employs a high gastric pH of 4.0.
Chemico-Biological Interactions, 1999
The urinary excretion of seven aldehydes, acetone, coproporphyrin III and 8-hydroxy-2%deoxyguanos... more The urinary excretion of seven aldehydes, acetone, coproporphyrin III and 8-hydroxy-2%deoxyguanosine (8-OH-dG) as non-invasive biomarkers of oxidative damage was measured in rats treated with diquat or N-nitrosodimethylamine (NDMA), two compounds causing hepatic damage by different mechanisms. Furthermore, the effect of co-administration of the aldehyde dehydrogenase inhibitor, calcium carbimide (CC) on the urinary excretion of the aldehydes was determined. Slight hepatotoxicity was found at the end of the experiment after treatment with NDMA (0.5, 4 and 8 mg/kg at t= 0, 48 and 96 h, respectively) or diquat (6.8 and 13.6 mg/kg at t= 0 and 48 h, respectively). In diquat treated rats slight nephrotoxicity was also found. Urinary excretion of aldehydes, acetone and coproporphyrin III remained largely unchanged in rats treated with NDMA. In the rats treated with diquat, the urinary excretion of several aldehydes was several-fold increased. An increase was also found in the urinary excretion of 8-OH-dG after the second dose of diquat. Treatment of rats with CC : S 0 0 0 9 -2 7 9 7 ( 9 8 ) 0 0 1 0 6 -9 L.L. de Zwart et al. / Chemico-Biological Interactions 117 (1999) 151-172 152 did not significantly influence the urinary excretion of aldehydes in control and NDMA rats. However, in rats treated with diquat, CC caused a potentiating effect on the excretion of acetaldehyde, hexanal and malondialdehyde (MDA), indicating that oxidation of aldehydes to carbonylic acids by aldehyde dehydrogenases (ALDHs) might be an important route of metabolism of aldehydes. In conclusion, increased urinary excretion of various aldehydes, acetone, coproporphyrin III and 8-OH-dG was observed after administration of diquat, probably reflecting oxidative damage induced by this compound. No such increases were found after NDMA administration, which is consistent with a different toxicity mechanism for NDMA. Therefore, excretion of aldehydes, acetone, coproporphyrin III and 8-OH-dG might be used as easily accessible urinary biomarkers of free radical damage.
British journal of clinical pharmacology, Jan 18, 2015
Ibrutinib, an inhibitor of Bruton's tyrosine kinase is used in the treatment of mantle cell l... more Ibrutinib, an inhibitor of Bruton's tyrosine kinase is used in the treatment of mantle cell lymphoma or chronic lymphocytic leukemia. Ibrutinib undergoes extensive rapid oxidative metabolism mediated by cytochrome P450 3A both at the level of first pass and clearance, which may result in low oral bioavailability. This study was designed to investigate the absolute bioavailability (F) of ibrutinib in fasted and in fed state and assess the effect of GFJ on the systemic exposure of ibrutinib in order to determine the fraction escaping the gut (Fg ) and the fraction escaping hepatic extraction (Fh ) in fed state. All participants received treatment A (560 mg PO ibrutinib, fasted), B (560 mg PO ibrutinib, fed, administered after drinking glucose drink) and C (140 mg PO ibrutinib, fed, with intake of GFJ before dosing). A single i.v. dose of 100 µg (13) C6 ibrutinib was administered 2 hours after each oral dose. The estimated 'F' for treatments A, B and C was 3.9%, 8.4% and 15...
Journal of Chromatography B: Biomedical Sciences and Applications, 1997
One of the major processes that occur as a result of radical-induced oxidative stress is lipid pe... more One of the major processes that occur as a result of radical-induced oxidative stress is lipid peroxidation (LPO). Degradation of lipid peroxides results in various products, including a variety of carbonyl compounds. In the present study eight different lipid degradation products, i.e., formaldehyde, acetaldehyde, acetone, propanal, butanal, pentanal, hexanal and malondialdehyde were identified and measured simultaneously and quantitatively in rat urine after derivatization with O-(2,3,4,5,6-pentafluorbenzyl)hydroxylamine hydrochloride, extraction with heptane and using gas chromatography-electron-capture detection (GC-ECD). The identity of the respective oximes in urine was confirmed by gas chromatography-negative ion chemical ionization mass spectrometry (GC-NCI-MS). Simultaneously measured standard curves were linear for all oxime-products and the detection limits were between 39.0 +/- 5.3 (n=9) and 500 +/- 23 (n=9) fmol per microl injected sample. Recoveries of all products from urine or water were 73.0 +/- 5.2% and higher. In urine of CCl4-treated rats an increase in all eight lipid degradation products in urine was found 24 h following exposure. ACON showed the most distinct increase, followed by PROPA, BUTA and MDA. It is concluded that the rapid, selective and sensitive analytical method based on GC-ECD presented here is well suited for routine measurement of eight different lipid degradation products. These products appear to be useful as non-invasive biomarkers for in vivo oxidative stress induced in rats by CCl4.
Antimicrobial Agents and Chemotherapy, 2010
Human respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in... more Human respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants, young children, elderly persons, and severely immunocompromised patients. Effective postinfection treatments are not widely available, and currently there is no approved vaccine. TMC353121 is a potent RSV fusion inhibitor in vitro, and its ability to reduce viral loads in vivo was demonstrated in cotton rats following prophylactic intravenous administration. Here, the pharmacokinetics of TMC353121 in the cotton rat, which is semipermissive for RSV replication, were further explored to build a pharmacokinetic-pharmacodynamic (PK-PD) model and to estimate the plasma drug levels needed for significant antiviral efficacy. TMC353121 reduced the viral titers in bronchoalveolar lavage fluid in a dose-dependent manner after a single subcutaneous administration and intranasal RSV inoculation 24 h after compound administration. The viral titer reduction and plasma TMC353121 concentration at the time of RSV inoculation were well described using a simple E max model with a maximal viral titer reduction (E max ) of 1.5 log 10 . The plasma drug level required to achieve 50% of the E max (200 ng/ml) was much higher than the 50% inhibitory concentration observed in vitro in HeLaM cells (0.07 ng/ml). In conclusion, this simple PK-PD approach may be useful in predicting efficacious exposure levels for future RSV inhibitors.
Antimicrobial agents and chemotherapy, 2010
Human respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in... more Human respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants, young children, elderly persons, and severely immunocompromised patients. Effective postinfection treatments are not widely available, and currently there is no approved vaccine. TMC353121 is a potent RSV fusion inhibitor in vitro, and its ability to reduce viral loads in vivo was demonstrated in cotton rats following prophylactic intravenous administration. Here, the pharmacokinetics of TMC353121 in the cotton rat, which is semipermissive for RSV replication, were further explored to build a pharmacokinetic-pharmacodynamic (PK-PD) model and to estimate the plasma drug levels needed for significant antiviral efficacy. TMC353121 reduced the viral titers in bronchoalveolar lavage fluid in a dose-dependent manner after a single subcutaneous administration and intranasal RSV inoculation 24 h after compound administration. The viral titer reduction and plasma TMC353121 concentration...
The American Journal of Forensic Medicine and Pathology, 2012
Postmortem redistribution of fentanyl in the rabbit was investigated after application of the 50-... more Postmortem redistribution of fentanyl in the rabbit was investigated after application of the 50-μg/h Durogesic pain patch. Patches were applied for 48 hours. Two cycles of patch administration were used before characterization of the postmortem redistribution. Fentanyl showed marked redistribution into the femoral and pulmonary veins of the rabbit through 48 hours after the animals were humanely killed and the pain patches removed. The plasma concentration of 2.34 ng/mL in the femoral blood before killing the animals increased 5.6-fold by 48 hours after patch removal to 13.2 ng/mL. This postmortem concentration is approximately 3-fold the C(max) determined during antemortem pharmacokinetic analysis, 4 ng/mL, which was achieved 24 hours after the application of the second 50-μg/h Durogesic pain patch. After blood sampling for 48 hours after animal termination with patch removal compared with sampling for 48 hours from animals not terminated and with patch removal, the exposure ratios in the terminated animals were approximately 30-fold, indicating that between the postmortem redistribution of fentanyl and the cessation of hepatic clearance of fentanyl in the rabbit, the postmortem redistribution of fentanyl leads to an elevated measures of postmortem blood concentrations relative to antemortem blood concentrations.
Based on ibrutinib pharmacokinetics and potential sensitivity towards CYP3A4-mediated DDI, a phys... more Based on ibrutinib pharmacokinetics and potential sensitivity towards CYP3A4-mediated DDI, a physiologically-based pharmacokinetic approach was developed to mechanistically describe DDI with various CYP3A4 perpetrators in healthy men under fasting conditions. These models were verified using clinical data for ketoconazole (strong CYP3A4 inhibitor) and used to prospectively predict and confirm the inducing effect of rifampin (strong CYP3A4 inducer); DDIs with mild (fluvoxamine, azithromycin) and moderate inhibitors (diltiazem, voriconazole, clarithromycin, itraconazole, erythromycin), and moderate (efavirenz) and strong CYP3A4 inducers (carbamazepine) were also predicted. Ketoconazole increased ibrutinib AUC by 24fold, while rifampin decreased ibrutinib AUC by 10-fold; coadministration of ibrutinib with strong inhibitors or inducers should be avoided. Ibrutinib dose should be reduced to 140 mg (quarter of maximal prescribed dose) when coadministered with moderate CYP3A4 inhibitors so that exposures remain within observed ranges at therapeutic doses. Thus, dose recommendations for CYP3A4 perpetrator use during ibrutinib treatment were developed and approved for labelling.
Archives of environmental contamination and toxicology, 2004
Soil ingestion is an important pathway of exposure for many nonvolatile contaminants for man and ... more Soil ingestion is an important pathway of exposure for many nonvolatile contaminants for man and in particular for children. A fraction of the ingested contaminant may not dissociate from the soil particles during digestion in the gastrointestinal tract, and is thus not available for transport across the intestinal epithelium. In order to estimate the contaminant fraction that is mobilized from soil, i.e., the bioaccessible fraction, several in vitro digestion models have been developed. The currently existing digestion models display many differences. One aspect that may affect bioaccessibility and may induce differences between digestion models is the bile that is used. Often freeze-dried bile of animal origin is preferred to purified bile salts. However, also the animal origin of bile may give rise to differences in bioaccessibility because bile composition appears to be species dependent. In the present study, we compared the bioaccessibility of benzo[a]pyrene, arsenic, cadmium,...
Journal of Chromatography B: Biomedical Sciences and Applications, 1997
One of the major processes that occur as a result of radical-induced oxidative stress is lipid pe... more One of the major processes that occur as a result of radical-induced oxidative stress is lipid peroxidation (LPO). Degradation of lipid peroxides results in various products, including a variety of carbonyl compounds. In the present study eight different lipid degradation products, i.e., formaldehyde, acetaldehyde, acetone, propanal, butanal, pentanal, hexanal and malondialdehyde were identified and measured simultaneously and quantitatively in rat urine after derivatization with O-(2,3,4,5,6-pentafluorbenzyl)hydroxylamine hydrochloride, extraction with heptane and using gas chromatography-electron-capture detection (GC-ECD). The identity of the respective oximes in urine was confirmed by gas chromatography-negative ion chemical ionization mass spectrometry (GC-NCI-MS). Simultaneously measured standard curves were linear for all oxime-products and the detection limits were between 39.0 +/- 5.3 (n=9) and 500 +/- 23 (n=9) fmol per microl injected sample. Recoveries of all products from urine or water were 73.0 +/- 5.2% and higher. In urine of CCl4-treated rats an increase in all eight lipid degradation products in urine was found 24 h following exposure. ACON showed the most distinct increase, followed by PROPA, BUTA and MDA. It is concluded that the rapid, selective and sensitive analytical method based on GC-ECD presented here is well suited for routine measurement of eight different lipid degradation products. These products appear to be useful as non-invasive biomarkers for in vivo oxidative stress induced in rats by CCl4.
Reproductive Toxicology, 2008
Knowledge of the ontogeny of the various systems involved in distribution and elimination of drug... more Knowledge of the ontogeny of the various systems involved in distribution and elimination of drugs is important for adequate interpretation of the findings during safety studies in juvenile animals.
Xenobiotica, 1996
1. 4-Hydroxy-2,3-nonenal (HNE) is an end product of lipid peroxidation (LPO) and a well known cyt... more 1. 4-Hydroxy-2,3-nonenal (HNE) is an end product of lipid peroxidation (LPO) and a well known cytotoxic aldehyde that exhibits a variety of biological effects. In this study the in vivo disposition and covalent binding of i.p. administered [2-3H]HNE was examined in the rat. 2. It was found that several metabolites of [2-3H]HNE are excreted in urine among which at least four mercapturic acids. 1,4-Dihydroxynonane mercapturic acid (DHN-MA) appeared to be the most abundant mercapturic acid excreted in urine (3.5% of the dose) and the excretion of the other three mercapturic acids amounted to 2% of the dose. 3. Within 48 h following i.p. administration of 5 or 25 mumol/kg bodyweight [2-3H]HNE (specific activity 4 microCi/mumol) about 25% of the radioactivity was excreted in urine, whereas 18% of the radioactivity appeared in the faeces. 4. After 48 h, 7% of the radioactivity was still present in the liver and 0.2% in other organs, but this radioactivity appeared to not to be covalently bound to cellular macromolecules. It was found that only 0.13% of the radioactivity was covalently bound in the liver and even less in other organs.
Toxicology and Applied Pharmacology, 1998
Carbon tetrachloride (CCl 4 ) is a model compound for inducing free radical damage in liver. In t... more Carbon tetrachloride (CCl 4 ) is a model compound for inducing free radical damage in liver. In this study 10 biomarkers in rats treated ip with three different single doses of CCl 4 (0.25, 0.50, and 1.00 ml/kg body wt) were measured dose and time dependently and compared to evaluate these urinary products as noninvasive biomarkers for radical damage. Eight degradation products of lipid peroxides, namely, formaldehyde, acetaldehyde, acetone, propanal, butanal, pentanal, hexanal, and malondialdehyde (MDA), 8-hydroxy-2-deoxyguanosine (8-OH-dG) and coproporphyrin III were measured in this study. As general measures of toxicity, several clinical chemical parameters (n ؍ 12) and histopathological damage were determined. A dose-dependent increase in both the clinical parameters and the lipid degradation products was found. Increases in lipid degradation products were statistically significant at doses of 0.5 and 1 ml/kg CCl 4 . An increase in these products was already found in the first 12 h after exposure. At the lowest dose, 0.25 ml/kg CCl 4 , acetaldehyde and propanal already showed a statistically significant increase as well. No change in the urinary levels of 8-OH-dG could be found in this study and a decrease in the urinary excretion of coproporphyrin III was found. It is concluded that 8-OH-dG and coproporphyrin III are not useful biomarkers for radical damage induced by CCl 4 . Lipid degradation products, however, are promising noninvasive biomarkers for in vivo radical damage, although the precise specificity of these biomarkers for damage induced by radicals needs to be further investigated.
Toxicological Sciences, 1998
There is an increasing need for biomarkers of oxidative stress in animals and man. In this study,... more There is an increasing need for biomarkers of oxidative stress in animals and man. In this study, we have evaluated in the rat the utility of various endogenous products that are excreted in urine as potential noninvasive biomarkers of oxidative stress in the kidney. Renal oxidative damage was induced by daily ip injections of ferric nitrilotriacetate (Fe-NTA) for a period of 13 days. The daily dose of Fe-NTA was increased during the experiment from 6 to 40 mg Fe/kg body wt. The levels of 8-hydroxy-2-deoxyguanosine (8-OHdG), coproporphyrin III (COPRO III), seven aldehydes, and acetone were determined in fractionated urine samples and compared with commonly used urinary and plasma clinical chemical parameters for toxicity. The parameters that showed the earliest increase were acetaldehyde (ACET), propanal (PROPA), and COPRO III. Their increase was significantly earlier than that of classical clinical chemical parameters indicative of renal damage such as urinary concentration of glucose (GLU) and protein (PRT), and N-acetyl--D-glucosaminidase (NAG) activity. The excretion of 8-OHdG was increased only after administration of the highest dose of Fe-NTA. Urinary excretion of acetone, formaldehyde (FOR), butanal (BUTA), pentanal (PENTA) hexanal (HEXA), and malondialdehyde (MDA) was also increased; however, their increase occurred only slightly before or simultaneously with that of the urinary clinical chemical parameters. In conclusion, 8-OHdG, acetone, FOR, BUTA, PENTA, HEXA, and MDA may possibly serve as biomarkers for oxidative kidney damage. COPRO III, ACET, and PROPA might even be used as biomarkers of production of reactive oxygen species at an early stage.
Reproductive Toxicology, 2008
With the growing experience in the conduct of juvenile toxicity studies for multiple classes of c... more With the growing experience in the conduct of juvenile toxicity studies for multiple classes of compound, the 'case-by-case' approach has become under much more pressure. Instead, a general screen or 'standard design' is now commonly expected by regulatory authorities with more routine inclusion of neurological and reproductive assessments. Minor modifications or additions can be made to the design to address specific questions according to the class of drug or intended clinical use. This drift from a 'case-by-case' approach to a 'standard design' approach is present within certain reviewing divisions of the FDA, often requesting by default a rodent and non-rodent juvenile animal study. However, juvenile animal studies should be designed thoughtfully to fulfil a purpose based on scientific rationale, with each endpoint carefully considered in terms of practicality and interpretability of data generated. Only when using the appropriate strategy and design may juvenile studies add value by (1) identifying potential safety or pharmacokinetic issues for drugs intended for paediatric use, (2) suggesting additional clinical endpoints and (3) adding new information to the product label. As the knowledge from juvenile animal studies in various species grows, a better understanding of the significance/relevance of findings will be achieved.
Regulatory Toxicology and Pharmacology, 2004
Whether children incur different risks from xenobiotics than adults will depend on the exposure, ... more Whether children incur different risks from xenobiotics than adults will depend on the exposure, biokinetics, and dynamics of compound. In this paper, current knowledge on developmental physiology and possible effects on biokinetics are evaluated and the role of biokinetics in risk assessment both for drugs and chemicals is discussed. It is concluded that most dramatic age-related physiological changes that may affect biokinetics occur in the first 6-12 months of age. The difference in internal exposure between children and adults can generally be predicted from already known developmental physiological differences. However, for risk assessment it will also be necessary to determine whether internal exposure is within the drug's therapeutic window or if it will exceed the NOAEL of a chemical. Furthermore, the effects of internal exposure of potentially harmful compounds on developing organ systems is of utmost importance. However, knowledge on this aspect is very limited. Risk assessment in children could be improved by: (1) application of pediatric PBPK-models in order to gain insight into internal exposure in children, (2) studies in juvenile animals for studying effects on developing systems, and (3) extrapolation of knowledge on the relationship between internal exposure and dynamics for drugs to other chemicals.
Free Radical Biology and Medicine, 1999
Free radical damage is an important factor in many pathological and toxicological processes. Desp... more Free radical damage is an important factor in many pathological and toxicological processes. Despite extensive research efforts in biomarkers in recent years, yielding promising results in experimental animals, there is still a great need for additional research on the applicability of, especially non-invasive, biomarkers of free radical damage in humans. This review gives an overview of the applications in experimental
Environmental Science & Technology, 2002
Soil ingestion can be a major exposure route for humans to many immobile soil contaminants. Expos... more Soil ingestion can be a major exposure route for humans to many immobile soil contaminants. Exposure to soil contaminants can be overestimated if oral bioavailability is not taken into account. Several in vitro digestion models simulating the human gastrointestinal tract have been developed to assess mobilization of contaminants from soil during digestion, i.e., bioaccessibility. Bioaccessibility is a crucial step in controlling the oral bioavailability for soil contaminants. To what extent in vitro determination of bioaccessibility is method dependent has, until now, not been studied. This paper describes a multi-laboratory comparison and evaluation of five in vitro digestion models. Their experimental design and the results of a round robin evaluation of three soils, each contaminated with arsenic, cadmium, and lead, are presented and discussed. A wide range of bioaccessibility values were found for the three soils: for As 6-95%, 1-19%, and 10-59%; for Cd 7-92%, 5-92%, and 6-99%; and for Pb 4-91%, 1-56%, and 3-90%. Bioaccessibility in many cases is less than 50%, indicating that a reduction of bioavailability can have implications for health risk assessment. Although the experimental designs of the different digestion systems are distinct, the main differences in test results of bioaccessibility can be explained on the basis of the applied gastric pH. High values are typically observed for a simple gastric method, which measures bioaccessibility in the gastric compartment at low pHs of 1.5. Other methods that also apply a low gastric pH, and include intestinal conditions, produce lower bioaccessibility values. The lowest bioaccessibility values are observed for a gastrointestinal method which employs a high gastric pH of 4.0.
Chemico-Biological Interactions, 1999
The urinary excretion of seven aldehydes, acetone, coproporphyrin III and 8-hydroxy-2%deoxyguanos... more The urinary excretion of seven aldehydes, acetone, coproporphyrin III and 8-hydroxy-2%deoxyguanosine (8-OH-dG) as non-invasive biomarkers of oxidative damage was measured in rats treated with diquat or N-nitrosodimethylamine (NDMA), two compounds causing hepatic damage by different mechanisms. Furthermore, the effect of co-administration of the aldehyde dehydrogenase inhibitor, calcium carbimide (CC) on the urinary excretion of the aldehydes was determined. Slight hepatotoxicity was found at the end of the experiment after treatment with NDMA (0.5, 4 and 8 mg/kg at t= 0, 48 and 96 h, respectively) or diquat (6.8 and 13.6 mg/kg at t= 0 and 48 h, respectively). In diquat treated rats slight nephrotoxicity was also found. Urinary excretion of aldehydes, acetone and coproporphyrin III remained largely unchanged in rats treated with NDMA. In the rats treated with diquat, the urinary excretion of several aldehydes was several-fold increased. An increase was also found in the urinary excretion of 8-OH-dG after the second dose of diquat. Treatment of rats with CC : S 0 0 0 9 -2 7 9 7 ( 9 8 ) 0 0 1 0 6 -9 L.L. de Zwart et al. / Chemico-Biological Interactions 117 (1999) 151-172 152 did not significantly influence the urinary excretion of aldehydes in control and NDMA rats. However, in rats treated with diquat, CC caused a potentiating effect on the excretion of acetaldehyde, hexanal and malondialdehyde (MDA), indicating that oxidation of aldehydes to carbonylic acids by aldehyde dehydrogenases (ALDHs) might be an important route of metabolism of aldehydes. In conclusion, increased urinary excretion of various aldehydes, acetone, coproporphyrin III and 8-OH-dG was observed after administration of diquat, probably reflecting oxidative damage induced by this compound. No such increases were found after NDMA administration, which is consistent with a different toxicity mechanism for NDMA. Therefore, excretion of aldehydes, acetone, coproporphyrin III and 8-OH-dG might be used as easily accessible urinary biomarkers of free radical damage.
British journal of clinical pharmacology, Jan 18, 2015
Ibrutinib, an inhibitor of Bruton's tyrosine kinase is used in the treatment of mantle cell l... more Ibrutinib, an inhibitor of Bruton's tyrosine kinase is used in the treatment of mantle cell lymphoma or chronic lymphocytic leukemia. Ibrutinib undergoes extensive rapid oxidative metabolism mediated by cytochrome P450 3A both at the level of first pass and clearance, which may result in low oral bioavailability. This study was designed to investigate the absolute bioavailability (F) of ibrutinib in fasted and in fed state and assess the effect of GFJ on the systemic exposure of ibrutinib in order to determine the fraction escaping the gut (Fg ) and the fraction escaping hepatic extraction (Fh ) in fed state. All participants received treatment A (560 mg PO ibrutinib, fasted), B (560 mg PO ibrutinib, fed, administered after drinking glucose drink) and C (140 mg PO ibrutinib, fed, with intake of GFJ before dosing). A single i.v. dose of 100 µg (13) C6 ibrutinib was administered 2 hours after each oral dose. The estimated 'F' for treatments A, B and C was 3.9%, 8.4% and 15...