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Influence of Malnutrition on the Pharmacokinetics of Drugs Used in the Treatment of Poverty-Related Diseases: A Systematic Review. Clin Pharmacokinet 2021; 60:1149-1169. [PMID: 34060020 PMCID: PMC8545752 DOI: 10.1007/s40262-021-01031-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2021] [Indexed: 11/06/2022]
Abstract
Background Patients affected by poverty-related infectious diseases (PRDs) are disproportionally affected by malnutrition. To optimize treatment of patients affected by PRDs, we aimed to assess the influence of malnutrition associated with PRDs on drug pharmacokinetics, by way of a systematic review. Methods A systematic review was performed on the effects of malnourishment on the pharmacokinetics of drugs to treat PRDs, including HIV, tuberculosis, malaria, and neglected tropical diseases. Results In 21/29 PRD drugs included in this review, pharmacokinetics were affected by malnutrition. Effects were heterogeneous, but trends were observed for specific classes of drugs and different types and degrees of malnutrition. Bioavailability of lumefantrine, sulfadoxine, pyrimethamine, lopinavir, and efavirenz was decreased in severely malnourished patients, but increased for the P-glycoprotein substrates abacavir, saquinavir, nevirapine, and ivermectin. Distribution volume was decreased for the lipophilic drugs isoniazid, chloroquine, and nevirapine, and the α1-acid glycoprotein-bound drugs quinine, rifabutin, and saquinavir. Distribution volume was increased for the hydrophilic drug streptomycin and the albumin-bound drugs rifampicin, lopinavir, and efavirenz. Drug elimination was decreased for isoniazid, chloroquine, quinine, zidovudine, saquinavir, and streptomycin, but increased for the albumin-bound drugs quinine, chloroquine, rifampicin, lopinavir, efavirenz, and ethambutol. Clinically relevant effects were mainly observed in severely malnourished and kwashiorkor patients. Conclusions Malnutrition-related effects on pharmacokinetics potentially affect treatment response, particularly for severe malnutrition or kwashiorkor. However, pharmacokinetic knowledge is lacking for specific populations, especially patients with neglected tropical diseases and severe malnutrition. To optimize treatment in these neglected subpopulations, adequate pharmacokinetic studies are needed, including severely malnourished or kwashiorkor patients. Supplementary Information The online version contains supplementary material available at 10.1007/s40262-021-01031-z.
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Mohamed WR, Kotb AS, Abd El-Raouf OM, Mohammad Fikry E. Apigenin alleviated acetaminophen-induced hepatotoxicity in low protein-fed rats: Targeting oxidative stress, STAT3, and apoptosis signals. J Biochem Mol Toxicol 2020; 34:e22472. [PMID: 32048452 DOI: 10.1002/jbt.22472] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 11/28/2019] [Accepted: 01/31/2020] [Indexed: 02/06/2023]
Abstract
Apigenin (API) is a natural flavonoid abundant in fruits and vegetables. The present study was undertaken to evaluate the effect of protein malnutrition (PMN) on acetaminophen (APAP)-induced hepatotoxicity, together with the protective effects of API, in male Wistar albino rats. In total, 64 male rats were divided into eight groups. Silymarin (SIL) (100 mg/kg, PO) as a reference standard and API (50 mg/kg, PO) were given to normal and APAP-induced hepatic injury in low protein-fed rats. The present results revealed that PMN significantly potentiated APAP-induced hepatotoxicity. Interestingly, the administration of SIL and API alleviated the induced damage, as revealed by reduced serum alanine aminotransferase and aspartate aminotransferase activities along with a significant improvement of the histopathological damage. API suppressed inflammatory response by reducing the interleukin-1β level and signal transducer and activator of transcription 3 expressions along with attenuating oxidative stress as shown by a significant reduction in liver contents of malondialdehyde and nitrite/nitrate as well as restoration of hepatic content of reduced glutathione and superoxide dismutase activity. API also counteracted apoptosis through downregulation of caspase-3 expression level. In conclusion, PMN greatly potentiated the hepatotoxic effects of APAP, and API produced a multimechanistic hepatoprotective activity that can be attributed to its antioxidant, anti-inflammatory, and antiapoptotic effects.
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Affiliation(s)
- Wafaa R Mohamed
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Beni-Suef University, Beni Suef, Egypt
| | - Amr S Kotb
- Department of Pharmacology, National Organization for Drug Control and Research, Giza, Egypt
| | - Ola M Abd El-Raouf
- Department of Pharmacology, National Organization for Drug Control and Research, Giza, Egypt
| | - Ebtehal Mohammad Fikry
- Department of Pharmacology, National Organization for Drug Control and Research, Giza, Egypt
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Konstandi M, Johnson EO, Lang MA. Consequences of psychophysiological stress on cytochrome P450-catalyzed drug metabolism. Neurosci Biobehav Rev 2014; 45:149-67. [DOI: 10.1016/j.neubiorev.2014.05.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 04/17/2014] [Accepted: 05/18/2014] [Indexed: 12/11/2022]
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TIAN X, XIANG Y, FAN Y, BU H, YANG H, MANYANDE A, GAO F, TIAN Y. Impact of malnutrition on propofol consumption and recovery time among patients undergoing laparoscopic gastrointestinal surgery. Acta Anaesthesiol Scand 2014; 58:942-7. [PMID: 25060045 DOI: 10.1111/aas.12373] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2014] [Indexed: 12/17/2022]
Abstract
BACKGROUND Malnutrition is a major health problem, especially in hospitalized patients as it can be closely related to many post-operative complications. However, research on malnutrition and its effect on the outcome of general anesthesia have been largely neglected. Here we investigated malnutrition status on propofol consumption and recovery time among patients undergoing laparoscopic gastrointestinal surgery under general anesthesia. METHODS One hundred and one patients were recruited between January and June 2012 at Tongji Hospital and assigned into three groups according to Nutritional Risk Screening Tool 2002 score. A standard combined general anesthesia procedure was performed under regular monitoring. The dosage of propofol needed for induction, consumption during maintenance and recovery time were recorded. RESULTS When compared with normal nutritional status individuals, the propofol dosage at induction was significantly decreased about 4.3% in moderate malnutritional status patients (P < 0.01) and about 16.8% in severely malnutritional status patients (P < 0.01). The average consumption of propofol was also significantly lower in malnourished individuals; for moderate malnutritional, the decrease was about 20% (P < 0.01) while for the severely malnutritional, it was 30% (P < 0.01) when compared with normal nutritional status individuals. For the recovery time of propofol anesthesia, the patients with severe malnutritional status awoke average 6.8 min later than those normally nourished (P < 0.01), but those patients with moderate malnutrition status did not (P = 0.885). CONCLUSION The present results indicate that the dosage and recovery time of propofol does change in malnourished individuals. Therefore, malnutrition may somehow affect the outcome of general anesthesia.
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Affiliation(s)
- X. TIAN
- Department of Anesthesiology; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - Y. XIANG
- Department of Ophthalmology; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - Y. FAN
- Department of Nutrition and Food Hygiene; School of Public Health; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - H. BU
- Department of Anesthesiology; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - H. YANG
- Department of Anesthesiology; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - A. MANYANDE
- School of Psychology; Social Work and Human Sciences; University of West London; London UK
| | - F. GAO
- Department of Anesthesiology; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - Y. TIAN
- Department of Anesthesiology; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
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Marzuillo P, Guarino S, Barbi E. Paracetamol: a focus for the general pediatrician. Eur J Pediatr 2014; 173:415-25. [PMID: 24374658 DOI: 10.1007/s00431-013-2239-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 12/05/2013] [Indexed: 02/02/2023]
Abstract
UNLABELLED Paracetamol (acetaminophen) is one of the most popular and widely used drugs for the treatment of pain and fever in children. This drug has multiple mechanisms of action, but its pharmacodynamic is still not well known. The central nervous system is the main site of action and it mirrors the paracetamol effect compartment. The recommended dosages and routes of administration should be different whether paracetamol is used for the treatment of pain or fever. For example, the rectal route, while being efficacious for the treatment of fever, should be avoided in pain management. Paracetamol is a safe drug, but some clinical conditions and concomitant drugs, which are frequent in clinical practice, may increase the risk of paracetamol toxicity. Therefore, it is important to optimize its administration to avoid overdoses and maximize its effect. The principal mediator of the paracetamol toxicity is the N-acetyl-p-benzo-quinone imine (NAPQI), a toxic product of the paracetamol metabolism, which could bind cysteine groups on proteins forming paracetamol-protein adduct in the liver. CONCLUSION Although frequently prescribed, the concept of "effect compartment concentration" and the possible co-factors that could cause toxicity at recommended doses are not familiar to all pediatricians and general practitioners. We reviewed the literature concerning paracetamol mechanisms of action, we highlighted some relevant pharmacodynamic concepts for clinical practice, and we summarized the possible risk factors for toxicity at therapeutic dosages.
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Affiliation(s)
- Pierluigi Marzuillo
- Department of Women and Children and General and Specialized Surgery, Seconda Università degli Studi di Napoli, Via L. De Crecchio 2, 80138, Naples, Italy,
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Konstandi M. Psychophysiological stress: a significant parameter in drug pharmacokinetics. Expert Opin Drug Metab Toxicol 2013; 9:1317-34. [DOI: 10.1517/17425255.2013.816283] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Miersch C, Döring F. Sex differences in body composition, fat storage, and gene expression profile in Caenorhabditis elegans in response to dietary restriction. Physiol Genomics 2013; 45:539-51. [PMID: 23715261 DOI: 10.1152/physiolgenomics.00007.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The metabolic and health-promoting effects of dietary restriction (DR) have been extensively studied in several species. The response to DR with respect to sex is essentially unknown. To address this question, we used the model organism Caenorhabditis elegans to analyze body composition and gene expression in males and hermaphrodites in response to DR. Unexpectedly, DR increased the fat-to-fat-free mass ratio and enlarged lipid droplets in both sexes to a similar extent. These effects were linked to a downregulation of the lipase-like 5 (lipl-5) gene in both sexes at two developmental stages. By contrast, the reductions in body size, protein content, and total RNA content in response to DR were more pronounced in hermaphrodites than in males. Functional enrichment analysis of gene expression data showed a DR-induced downregulation of several embryogenesis-associated genes concomitant with an ongoing expression of sperm-associated genes in hermaphrodites. In conclusion, DR increases fat stores in both sexes of C. elegans in the form of large and possibly lipolysis-resistant lipid droplets and markedly alters the reproductive program in hermaphrodites but not in males.
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Affiliation(s)
- Claudia Miersch
- Department of Molecular Prevention, Institute of Human Nutrition and Food Science, Christian-Albrechts-University of Kiel, Germany
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Altmann S, Murani E, Schwerin M, Metges CC, Wimmers K, Ponsuksili S. Dietary protein restriction and excess of pregnant German Landrace sows induce changes in hepatic gene expression and promoter methylation of key metabolic genes in the offspring. J Nutr Biochem 2013; 24:484-95. [DOI: 10.1016/j.jnutbio.2012.01.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 01/26/2012] [Indexed: 02/01/2023]
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Influence of CYP2C9 genetic polymorphism and undernourishment on plasma-free phenytoin concentrations in epileptic patients. Ther Drug Monit 2011; 32:762-6. [PMID: 21068649 DOI: 10.1097/ftd.0b013e3181fa97cc] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The objective of this study was to study the effect of CYP2C9 genetic polymorphism and undernourishment on free phenytoin concentrations in epileptic patients. The study was done in 70 patients who were taking phenytoin therapy for the treatment of epileptic seizures. Genotyping of CYP2C9 (*2 and *3) was determined by the polymerase chain reaction-restriction fragment length polymorphism method. Bound and free plasma phenytoin was separated using equilibrium dialysis technique. Total and free phenytoin concentrations were measured by the reverse-phase high-performance liquid chromatography method. Patients were broadly classified into well-nourished and undernourished and further subclassified by CYP2C9 genotypes. In well-nourished groups (G1 to G3 group), free phenytoin concentrations were significantly higher in the heterozygous poor metabolizer of CYP2C9 genotype (G2) group (3.1 ± 0.62 μg/mL) and homozygous poor metabolizer of CYP2C9 genotype (G3) group (4.3 ± 1.76 μg/mL) when compared with patients with the wild-type CYP2C9 (G1) group (1.1 ± 0.72 μg/mL). Similarly, in undernourished patient groups (G4-G6 group), free phenytoin concentrations were significantly higher in the wild-type CYP2C9 (G4) group (2.5 ± 0.52 μg/mL), heterozygous poor metabolizer of CYP2C9 genotype (G5) group (4.3 ± 1.76 μg/mL), and homozygous poor metabolizer of CYP2C9 genotype (G6) group (8.2 ± 1.08 μg/mL) when compared with well-nourished patients with the wild-type CYP2C9 (G1) group (1.1 ± 0.72 μg/mL). The percentage increase in free phenytoin concentration by undernourishment, CYP2C9 allelic variants, and undernourishment cum CYP2C9 allelic variants were 127%, 290%, and 472%, respectively, compared with well-nourished patients with the wild-type CYP2C9 genotype (G1) group. The contribution of undernourishment and genetic factors (CYP2C9 allelic variant) for developing phenytoin toxicity was calculated to have an odds ratio of 37.3 (P < 0.0001). Undernourishment and variant CYP2C9 alleles elevate free phenytoin concentrations individually and in combination show additive effects.
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Ulaganatha I, Divya D, Radha K, Vijayakuma T, Dhanaraju M. Protective Effect of Luffa acutangula (var) amara against Carbon Tetrachloride-Induced Hepatotoxicity in Experimental Rats. ACTA ACUST UNITED AC 2010. [DOI: 10.3923/rjbsci.2010.615.624] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Cherala G, Shapiro BH, D'mello AP. Effect of Perinatal Low Protein Diets on the Ontogeny of Select Hepatic Cytochrome P450 Enzymes and Cytochrome P450 Reductase in the Rat. Drug Metab Dispos 2007; 35:1057-63. [PMID: 17392395 DOI: 10.1124/dmd.106.013748] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the present study, we administered two low protein diets (LPDs) to rats during pregnancy and lactation and determined their effect on the ontogeny of select hepatic cytochrome P450 (P450) isoforms in their offspring. The L93 and LM76 LPDs were derived from the American Society of Nutrition recommended AIN93G and a modified version of the AIN76A purified control diets, respectively. The LPDs contained 8% crude protein in the form of casein, whereas the purified control diets contained 19% casein. A regular cereal-based diet (NP) was also included, and, therefore, a total of five groups were tested. Pups in all five groups were weaned onto a regular NP diet on postnatal day 28. Perinatal LPD altered the activities of a number of P450 isoforms in 28-day-old male and female offspring. However, nutritional rehabilitation abolished most of these changes as evidenced by lack of differences between the five groups in the activities of P450 isoforms in either 65- or 150-day-old offspring. Interestingly, 58-day-old female offspring in the LM76 group but not those in the L93 group exhibited shorter hexobarbital sleep time than the purified control group. However, hexobarbital hydroxylase activity and the amount of CYP2C12 protein, an important P450 isoform involved in hexobarbital metabolism in females, were unchanged. This suggests that the decrease in hexobarbital sleep time in this group is not due to an increase in the activity of hexobarbital-metabolizing enzymes. In summary, perinatal LPDs produced transient alterations in activities of select hepatic P450s and resulted in a gender- and diet-dependent long-term alteration in hexobarbital pharmacodynamics.
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Affiliation(s)
- Ganesh Cherala
- Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
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Williams ML, Mager DE, Parenteau H, Gudi G, Tracy TS, Mulheran M, Wainer IW. Effects of protein calorie malnutrition on the pharmacokinetics of ketamine in rats. Drug Metab Dispos 2005; 32:786-93. [PMID: 15258102 DOI: 10.1124/dmd.32.8.786] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of protein calorie malnutrition (PCM) on the pharmacokinetics of ketamine (KET) enantiomers has been investigated. Six control and six PCM rats were administered 85 mg/kg racemic KET by intramuscular injection, and plasma concentrations of (S)- and (R)-KET, norketamine (NKET), and 5,6-dehydronorketamine (DNK) were measured using enantioselective gas chromatography. Pharmacokinetic profiles were analyzed using standard noncompartmental and compartmental modeling methods. The volumes of distribution were similar between control and PCM rats for (S)- and (R)-KET. However, total clearance of both KET enantiomers was decreased, resulting in an increase in systemic exposure (p < 0.05). The KET absorption rate was also increased in PCM rats. A decrease in the clearance of both NKET enantiomers led to a significant increase in exposure in PCM rats (p < 0.005), and modeling results could not exclude the possibility that PCM induced an increase in the fraction of KET following the NKET pathway, which may further contribute to this increase in exposure. An increase in exposure to DNK enantiomers was also evident in PCM animals compared with controls [p < 0.005 (DNK1); N.S. (DNK2)], which was in concordance with the decrease in apparent clearance values. These results show that PCM significantly alters the pharmacokinetics of KET and several of its metabolites.
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Affiliation(s)
- Marion L Williams
- National Institute on Aging, National Institutes of Health, Gerontology Research Center, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825, USA.
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Abstract
Unlike the bulk of medications, described in this fascicle, that cause liver injury in humans, acetaminophen is a non-prescription drug that can be purchased in drug stores and supermarkets without a physician's involvement. Death or severe injury is far more likely to occur with its use than with all the other medications considered in this study. Whereas attempts to control the quantity of drug ingested have been made in the United Kingdom and elsewhere in Europe, no comparable moves have taken place in the United States. The Food and Drug Administration claims to have concerns about the situation, however, but has yet to make an effort to more closely regulate the marketing and distribution of the drug. It is to be hoped that this will not be the case by the time the next issue of Drug Hepatotoxicity is scheduled for this series.
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Affiliation(s)
- Matthew Q Bromer
- Abdominal Organ Transplantation Program, Division of Gastroenterology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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Williams ML, Wainer IW. Role of chiral chromatography in therapeutic drug monitoring and in clinical and forensic toxicology. Ther Drug Monit 2002; 24:290-6. [PMID: 11897974 DOI: 10.1097/00007691-200204000-00010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Advances in chiral chromatographic separations have given pharmacologists and toxicologists the tools to examine unexpected clinical results involving chiral drugs. The ability to unravel complex phenomena associated with drug transport and drug metabolism is presented in this manuscript. The relation between the chirality of the drug mefloquine and the intracellular concentrations of the drug cyclosporine is illustrated by examining the effect of the enantiomers of mefloquine on the transport activity of P-glycoprotein (Pgp). These studies were conducted using a liquid chromatographic column containing immobilized Pgp. The results demonstrated that (+)-mefloquine competitively displaced the Pgp substrate cyclosporine whereas (-)-mefloquine had no effect on cyclosporine-Pgp binding. The data suggest that cyclosporine cellular and CNS concentrations can be increased through the concomitant administration of (+)-mefloquine. The use of chirality in clinical and forensic situations is also illustrated by the metabolism of the enantiomers of ketamine (KET). The plasma concentrations of (+)-KET and (-)-KET and the norketamine metabolites (+)-NK and (-)-NK were measured in rat plasma using enantioselective gas chromatography. The separations were accomplished using a gas chromatography chiral stationary phase based on beta-cyclodextrin. The pharmacokinetic profiles of (+)-, (-)-KET and (+)-, (-)-NK were determined in control and protein-calorie malnourished (PCM) rats to determine the effect of PCM on ketamine metabolism and clearance. The results indicate that PCM produced a significant and stereoselective decrease in KET and NK metabolism. The data suggest that the effects of environmental factors (smoking, alcohol use, diet) and drug interactions (coadministered agents) can be measured using the changes in stereochemical metabolic and pharmacokinetic patterns of KET and similar drugs.
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Affiliation(s)
- Marion L Williams
- Department of Oncology, Leicester University, Leicester, United Kingdom
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Abstract
Acetaminophen is widely used in children, because its safety and efficacy are well established. Although the risk of developing toxic reactions to acetaminophen appears to be lower in children than in adults, such reactions occur in pediatric patients from intentional overdoses. Less frequently, acetaminophen toxicity is attributable to unintended inappropriate dosing or the failure to recognize children at increased risk in whom standard acetaminophen doses have been administered. Because the symptoms of acetaminophen intoxication are nonspecific, the diagnosis and treatment of acetaminophen intoxication are more likely to be delayed in unintentional cases of toxicity. This statement describes situations and conditions that may contribute to acetaminophen toxicity not associated with suicidal intentions.
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Casalino E, Calzaretti G, Sblano C, Landriscina C. Cadmium-dependent enzyme activity alteration is not imputable to lipid peroxidation. Arch Biochem Biophys 2000; 383:288-95. [PMID: 11185565 DOI: 10.1006/abbi.2000.2056] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effect of cadmium on the liver-specific activities of NADPH-cytochrome P450 reductase (CPR), malic dehydrogenase (MDH), glyceraldehyde-3-phosphate dehydrogenase (GADPH), and sorbitol dehydrogenase (SDH) was assessed 6, 24, and 48 h after administration of the metal to rats (2.5 mg/kg of body weight, as CdCl2, single ip injection). CPR specific activity increased after 6 h and afterward decreased significantly, while MDH specific activity increased up to 24 h and then remained unchanged. Both SDH and GADPH specific activities reduced after 6 h, the former only a little but the latter much more, and after 24 and 48 h were strongly inhibited. In vitro experiments, by incubating rat liver microsomes, mitochondria, or cytosol with CdCl2 in the pH range 6.0-8.0, excluded cadmium-induced lipid peroxidation as the cause of the reduction in enzyme activity. In addition, from these experiments, we obtained indications on the type of interactions between cadmium and the enzymes studied. In the case of CPR, the inhibitory effect is probably due to Cd2+ binding to the histidine residue of the apoenzyme, which, at physiological pH, acts as a nucleophilic group. In vitro, mitochondrial MDH was not significantly affected by cadmium at any pH, indicating that this enzyme is probably not involved in the decrease in mitochondrial respiration caused by this metal. As for GADPH specific activity, its inhibition at pH 7.4 and above is imputable to the binding of cadmium to the SH groups present in the enzyme active site, since in the presence of dithiothreitol this inhibition was removed. SDH was subjected to a dual effect when cytosol was exposed to cadmium. At pH 6.0 and 6.5, its activity was strongly stimulated up to 75 microM CdCl2 while at higher metal concentrations it was reduced. At pH 7.4 and 8.0, a stimulation up to 50 microM CdCl2 occurred but above this concentration, a reduction was found. These data seem to indicate that cadmium can bind to different enzyme sites. One, at low cadmium concentration, stimulates the SDH activity while the other, at higher metal concentrations, substitutes for zinc, thus causing inhibition. This last possibility seems to occur in vivo essentially at least 24 h after intoxication. The cadmium-induced alterations of the investigated enzymes are discussed in terms of the metabolic disorders produced which are responsible for several pathological conditions.
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Affiliation(s)
- E Casalino
- Department of Pharmaco-Biology, University of Bari, Valenzano, Italy
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