Toxicokinetics and Hydrolysis of Artelinate and Artesunate in Malaria-Infected Rats

2005 ◽  
Vol 24 (4) ◽  
pp. 241-250 ◽  
Author(s):  
Qigui Li ◽  
Lisa H. Xie ◽  
Yuanzheng Si ◽  
Elaine Wong ◽  
Ravi Upadhyay ◽  
...  
Keyword(s):  
Drug Exposure ◽  
Enterohepatic Circulation ◽  
Metabolizing Enzymes ◽  
Antimalarial Agents ◽  
Elimination Half ◽  
Conversion Rates ◽  
Daily Dose ◽  
Exposure Levels ◽  
Distribution Studies ◽  
Hydrolysis Of

Comparative toxicokinetic (TK) and hydrolysis studies of intravenously administered two new antimalarial agents, artelinate (AL) and artesunate (AS), were performed in malaria-infected rats using three daily equimolar doses (96 μmoles/kg). The TK evaluation was related to select one drug for severe malaria treatment in U.S. Army. Drug concentration of AS with daily dose of 36.7 mg/kg was one-third less on day 3 than on day 1, which resembled its active metabolite, dihydroartemisinin (DHA), suggesting an autoinduction of hepatic drug-metabolizing enzymes for AS. The results were similar to other artemisinin drugs, but not for AL. TK parameters of AL were very comparable from day 1 to day 3 at same AS molecular dose at 40.6 mg/kg. AS is the prodrug of DHA with the DHA/AS ratio of 5.26 compared to the ratio of 0.01 for DHA/AL. Other TK parameters revealed that the total AUC1–3 days (84.4 μg · h ml−1) of AL was fivefold higher than that of AS (15.7 mu;g h ml−1 of AS plus DHA). The elimination half-life of AL (7.1 h) was much longer than that of AS (0.36 h) or DHA (0.72 h). The remarkable alteration of the TK shape of AL may be caused by poor conversion rates to DHA and an enterohepatic circulation, which is confirmed by the present TK and tissue distribution studies. Compared to AS, higher drug exposure levels and longer exposure time of AL in the rat blood may be the cause of its increased toxicity.

Influence of cyp2d6 polymorphisms on pharmacokinetics, efficacy and safety of antipsychotics

2018 ◽  
pp. 26-39
Author(s):  
А.А. Курылев ◽  
Б.В. Андреев
Keyword(s):  
Genetic Polymorphisms ◽  
Atypical Antipsychotics ◽  
Retrospective Studies ◽  
Pharmacokinetic Parameters ◽  
Clinical Routine ◽  
Elimination Half ◽  
Daily Dose ◽  
Comparison Groups ◽  
Cyp2d6 Polymorphisms ◽  
Positive Significant Correlation

Несмотря на доступность в клинической практике широкого круга классических и атипичных антипсихотиков (АП), по-прежнему наблюдается широкая вариабельность ответа на психофармакотерапию. Эта вариабельность обусловлена генетической гетерогенностью как самой шизофрении, так и метаболизма АП. Стандартные назначаемые дозы АП далеко не всегда являются оптимальными. Генетическая вариабельность систем биотрансформации и биодоступности АП могут играть значимую роль в формировании ответа на терапию и развитии нежелательных реакций. Целью исследования стало проведение обзора литературы по проблеме клинической эффективности применения генотипирования полиморфизмов CYP2D6 при терапии антипсихотиками. Большинство фармакокинетических исследований обнаруживают сильную достоверную положительную корреляцию метаболического статуса CYP2D6, определенного путем генотипирования полиморфизмов CYP2D6 и фармакокинетических параметров АП (AUC, период полувыведения, клиренс). Однако статистически достоверных связей между полиморфизмами CYP2D6 и эффективностью терапии АП в большинстве исследований обнаружено не было, прежде всего из-за недостаточного количества участников, гетерогенности сравниваемых когорт, применении различных АП и использовании разных критериев эффективности. Перспективные исследования с хорошо сбалансированными группами сравнения, а также масштабные ретроспективные исследования демонстрируют достоверную корреляцию метаболического статуса CYP2D6 и частоты развития нежелательных реакций АП (лекарственный паркинсонизм и поздняя дискинезия). Для более точной оценки величины вклада генетических полиморфизмов CYP2D6 в эффективность и безопасность психофармакотерапии необходимы масштабные перспективные клинические исследования. Although a number of typical and atypical antipsychotics (AP) have been discovered and used in psychiatric clinical practice the variability in response to AP is quite high. This variability is partially explained by a genetic heterogeneity of schizophrenia and metabolism of AP. The standard prescribed antipsychotic daily dose is not always optimal. Genetic variability of biotransformation and bioavailability of AP may significantly influence on therapeutic effect and tolerability. The aim of the study was to perform literature review of studies evaluating the correlation of CYP2D6 genetic polymorphisms and AP pharmacokinetics, effectiveness and safety. Most pharmacokinetics studies show high positive significant correlation between CYP2D6 metabolic activity, determined by CYP2D6 polymorphisms genotyping and AP pharmacokinetic parameters (AUC, elimination half-life, clearance etc.). However the majority of studies were failed to demonstrate significant correlation between CYP2D6 polymorphisms and AP effectiveness mainly due to inadequate number of patient, heterogeneous cohorts, different AP and effectiveness criteria used. Prospective studies with balanced comparison groups and large retrospective studies showed significant correlation between CYP2D6 metabolic status and the frequency of AP induced AEs (parkinsonism and tardive dyskinesia). To better assess the influence of CYP2D6 genetic polymorphisms on AP effectiveness and safety in clinical routine large prospective well designed clinical studies are needed.

scholarly journals Cerebrospinal fluid ceftazidime kinetics in patients with external ventriculostomies.

1996 ◽  
Vol 40 (3) ◽  
pp. 763-766 ◽  
Author(s):  
R Nau ◽  
H W Prange ◽  
M Kinzig ◽  
A Frank ◽  
A Dressel ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Cerebrospinal Fluid ◽  
Nervous System ◽  
High Performance ◽  
Elimination Half ◽  
Daily Dose ◽  
Order Of Magnitude ◽  
The Central Nervous System ◽  
Occlusive Hydrocephalus ◽  
A Minor

Ceftazidime has proven to be effective for the treatment of bacterial meningitis caused by multiresistant gram-negative bacteria. Since nosocomial central nervous system infections are often accompanied by only a minor dysfunction of the blood-cerebrospinal fluid (CSF) barrier, patients with noninflammatory occlusive hydrocephalus who had undergone external ventriculostomy were studied (n = 8). Serum and CSF were drawn repeatedly after the administration of the first dose of ceftazidime (3 g over 30 min intravenously), and concentrations were determined by high-performance liquid chromatography by using UV detection. The concentrations of ceftazidime in CSF were maximal at 1 to 13 h (median, 5.5 h) after the end of the infusion and ranged from 0.73 to 2.80 mg/liter (median, 1.56 mg/liter). The elimination half-lives were 3.13 to 18.1 h (median, 10.7 h) in CSF compared with 2.02 to 5.24 h (median, 3.74 h) in serum. The ratios of the areas under the concentration-time curves in CSF and serum (AUCCSF/AUCS) ranged from 0.027 to 0.123 (median, 0.054). After the administration of a single dose of 3 g, the maximum concentrations of ceftazidime in CSF were approximately four times higher than those after the administration of 2-g intravenous doses of cefotaxime (median, 0.44 mg/liter) and ceftriaxone (median, 0.43 mg/liter) (R. Nau, H. W. Prange, P. Muth, G. Mahr, S. Menck, H. Kolenda, and F. Sörgel, Antimicrob. Agents Chemother. 37:1518-1524, 1993). The median AUCCSF/AUCS ratio of ceftazidime was slightly below that of cefotaxime (0.12), but it was 1 order of magnitude above the median AUCCSF/AUCS of ceftriaxone (0.007) (Nau et al., Antimicrob. Agents Chemother. 37:1518-1524, 1993). The concentrations of ceftazidime observed in CSF were above the MICs for most Pseudomonas aeruginosa strains. However, they are probably not high enough to be rapidly bactericidal. For this reason, the daily dose should be increased to 12 g in cases of P. aeruginosa infections of the central nervous system when the blood-CSF barrier is minimally impaired.

Influence of dopamine on cyclic nucleotide enzymes in bovine retinal membrane fractions

1993 ◽  
Vol 10 (6) ◽  
pp. 991-996 ◽  
Author(s):  
Ari Sitaramayya ◽  
Lorraine Lombardi ◽  
Alexander Margulis
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Cyclic Nucleotide ◽  
D2 Receptors ◽  
D1 Receptors ◽  
Metabolizing Enzymes ◽  
D2 Agonist ◽  
Hydrolysis Of ◽  
Cyclic Amp Synthesis

AbstractDopamine is a major neurotransmitter and neuromodulator in vertebrate retina. Although its pharmacological and physiological actions are well understood, the biochemical mechanisms of its signal transduction are less clear. Acting via D1 receptors, dopamine was shown to increase cyclic AMP levels in intact retina and to activate adenylate cyclase in retinal homogenates. The action via activation of D2 receptors is controversial: it was reported to decrease cyclic AMP levels in intact retina but inhibition of cyclase could not be demonstrated in retinal homogenates; also it was reported to activate rod outer segment cyclic GMP phosphodiesterase in vitro but did not decrease cyclic GMP levels in aspartate-treated retinas. We made an attempt to fractionate bovine retinal membranes and to investigate the effects of dopamine, via Dl and D2 receptors, on the synthesis and hydrolysis of cyclic AMP and cyclic GMP. Activation of cyclic AMP synthesis was noted in all fractions, but no effects were evident on cyclic nucleotide hydrolysis or cyclic GMP synthesis in any fraction. Also, D2 agonist did not inhibit cyclic AMP synthesis. These observations suggest that D2 receptors may not be directly coupled to cyclic nucleotide metabolizing enzymes in bovine retina.

scholarly journals Measuring drug exposure: concordance between defined daily dose and days' supply depended on drug class

2016 ◽  
Vol 69 ◽  
pp. 107-113 ◽  
Author(s):  
Sarah-Jo Sinnott ◽  
Jennifer M. Polinski ◽  
Stephen Byrne ◽  
Joshua J. Gagne
Keyword(s):  
Drug Exposure ◽  
Drug Class ◽  
Defined Daily Dose ◽  
Daily Dose

scholarly journals Perfluoroalkyl Carboxylic Acids Interact with the Human Bile Acid Transporter NTCP

Livers ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 221-229
Author(s):  
Melissa J. Ruggiero ◽  
Haley Miller ◽  
Jessica Y. Idowu ◽  
Jeremiah D. Zitzow ◽  
Shu-Ching Chang ◽  
...  
Keyword(s):  
Competitive Inhibition ◽  
Enterohepatic Circulation ◽  
Human Bile ◽  
Human Embryonic Kidney Cells ◽  
Elimination Half ◽  
Sodium Dependent ◽  
Km Value ◽  
Bile Acid Transporter ◽  
Dependent Transport ◽  
Chain Lengths

Na+/taurocholate cotransporting polypeptide (NTCP) is important for the enterohepatic circulation of bile acids, which has been suggested to contribute to the long serum elimination half-lives of perfluoroalkyl substances in humans. We demonstrated that some perfluoroalkyl sulfonates are transported by NTCP; however, little was known about carboxylates. The purpose of this study was to determine if perfluoroalkyl carboxylates would interact with NTCP and potentially act as substrates. Sodium-dependent transport of [3H]-taurocholate was measured in human embryonic kidney cells (HEK293) stably expressing NTCP in the absence or presence of perfluoroalkyl carboxylates with varying chain lengths. PFCAs with 8 (PFOA), 9 (PFNA), and 10 (PFDA) carbons were the strongest inhibitors. Inhibition kinetics demonstrated competitive inhibition and indicated that PFNA was the strongest inhibitor followed by PFDA and PFOA. All three compounds are transported by NTCP, and kinetics experiments revealed that PFOA had the highest affinity for NTCP with a Km value of 1.8 ± 0.4 mM. The Km value PFNA was estimated to be 5.3 ± 3.5 mM and the value for PFDA could not be determined due to limited solubility. In conclusion, our results suggest that, in addition to sulfonates, perfluorinated carboxylates are substrates of NTCP and have the potential to interact with NTCP-mediated transport.

A single-center, open-label, dose escalation, safety, and pharmacokinetic study of ENMD-1198 administered orally to patients (pts) with advanced cancer

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. 3562-3562
Author(s):  
S. Nallapareddy ◽  
D. Gustafson ◽  
S. Leong ◽  
W. Messersmith ◽  
J. Arnott ◽  
...  
Keyword(s):  
Advanced Cancer ◽  
Dose Escalation ◽  
Drug Exposure ◽  
Phase 1 ◽  
Performance Status ◽  
Maximum Tolerated Dose ◽  
Open Label ◽  
Significant Treatment ◽  
Elimination Half ◽  
Label Dose

3562 Background: ENMD-1198 (2-methoxyestra-1, 3, 5, (10) 16-tetraene-3-carboxamide), an analog of 2-methoxyestradiol (2ME2), has both antiangiogenic and antiproliferative effects in various tumor types. ENMD-1198 inhibits MT polymerization by binding to β-tubulin at the colchicine-binding site and inhibits HIF-1alpha. This Phase 1 study is evaluating the safety of ENMD-1198 to determine the maximum tolerated dose. Methods: Eligible pts had advanced cancer for which no effective therapy exists that is either evaluable by RECIST criteria or tumor markers that could be monitored for clinical benefit. Phase 1 dose escalation in 3+3 design for first 5 cohorts; modified to 1 pt cohorts for subsequent cohorts until Grade 2 treatment related toxicity, and then standard 3+3 design. All pts treated with once daily oral ENMD-1198 in 28-day cycles (with post-treatment drug-free observation period of 7–14 days in Cycle 1 only). Pts are treated until the appearance of significant treatment-emergent toxicities or disease progression (PD) occurs. Results: To date, 27 pts have been enrolled in 12 dose cohorts (range 5 to 550 mg/m2/d). Median age/performance status is 61/1. Total # of treatment cycles to date is 68, with a median of 2 cycles (range <1 to 15 cycles). Most frequent toxicities (all grades, n=22) were pain (77%), fatigue (55%), constipation (36%), neuropathy and nausea (both 32%), and anemia (27%). 4 pts have experienced stable disease (SD) for more than 2 cycles. There have been no objective responses to date. 2 pts experienced dose limiting toxicity with Grade 4 neutropenia in the 550 mg/m2/d cohort. Following drug holiday, pts restarted at 425 mg/m2/d and continued for at least 1–2 more cycles before being removed from study for PD. One pt (neuroendocrine ca pancreas) is experiencing prolonged SD at 60 mg/m2/d >14 cycles and a 2nd pt (prostate ca) experienced SD at 30mg/m2/d for 10 cycles. ENMD-1198 was absorbed rapidly after oral administration. There was a linear relationship between dose and drug exposure as measured by AUC across all doses (5 - 550 mg/m2). The elimination half-life of ENMD- 1198 averaged more than 12 hours after a single dose. Conclusions: DLT was identified at 550 mg/m2/d. Cohort expansion at 425mg/m2/d is ongoing. [Table: see text]

Sign in / Sign up

Export Citation Format

Share Document