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1.
Clin Pharmacol Drug Dev ; 13(6): 665-671, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38523487

RESUMO

Tozorakimab is a high-affinity human immunoglobulin G1 monoclonal antibody that neutralizes interleukin (IL)-33, an IL-1 family cytokine. This phase 1, single-center, randomized, double-blind, placebo-controlled, single ascending dose study (NCT05070312) evaluated tozorakimab in a healthy Chinese population. Outcomes included the characterization of the pharmacokinetic (PK) profile and immunogenicity of tozorakimab. Safety outcomes included treatment-emergent adverse events (TEAEs) and clinical laboratory, electrocardiogram, and vital sign parameters. Healthy, non-smoking, male, and female Chinese participants aged 18-45 years with a body mass index 19-24 kg/m2 were enrolled. In total, 36 participants across 2 cohorts of 18 participants were randomized 2:1 to receive a single subcutaneous dose of tozorakimab (300 mg [2 mL] or 600 mg [4 mL]) or matching placebo (2 or 4 mL). Tozorakimab showed dose-dependent serum PK concentrations with an approximate monophasic distribution in serum over time and a maximum observed peak concentration of 20.1 and 33.7 µg/mL in the 300- and 600-mg cohorts, respectively. No treatment-emergent anti-drug antibodies for tozorakimab were observed in any of the participants. There were no clinically relevant trends in the occurrence of TEAEs across the treatment groups. There were no clinically relevant trends over time in clinical laboratory (hematology, clinical chemistry, and urinalysis), electrocardiogram, or vital sign parameters in any treatment group. Overall, tozorakimab demonstrated dose-dependent systemic exposure in healthy Chinese participants and was well tolerated, with no safety concerns identified in this study.


Assuntos
Anticorpos Monoclonais Humanizados , Povo Asiático , Relação Dose-Resposta a Droga , Voluntários Saudáveis , Humanos , Método Duplo-Cego , Feminino , Masculino , Adulto , Injeções Subcutâneas , Adulto Jovem , Anticorpos Monoclonais Humanizados/farmacocinética , Anticorpos Monoclonais Humanizados/administração & dosagem , Anticorpos Monoclonais Humanizados/efeitos adversos , Pessoa de Meia-Idade , Adolescente , China , População do Leste Asiático
2.
Clin Pharmacol Ther ; 115(3): 565-575, 2024 03.
Artigo em Inglês | MEDLINE | ID: mdl-38115209

RESUMO

Tozorakimab is a human monoclonal antibody that neutralizes interleukin (IL)-33. IL-33 is a broad-acting epithelial "alarmin" cytokine upregulated in lung tissue of patients with chronic obstructive pulmonary disease (COPD). This first-in-human, phase I, randomized, double-blind, placebo-controlled study (NCT03096795) evaluated the safety, tolerability, pharmacokinetics (PKs), immunogenicity, target engagement, and pharmacodynamics (PDs) of tozorakimab. This was a 3-part study. In part 1, 56 healthy participants with a history of mild atopy received single escalating doses of either intravenous or subcutaneous tozorakimab or placebo. In part 2, 24 patients with mild COPD received multiple ascending doses of subcutaneous tozorakimab or placebo. In part 3, 8 healthy Japanese participants received a single intravenous dose of tozorakimab or placebo. The safety data collected included treatment-emergent adverse events (TEAEs), vital signs, and clinical laboratory parameters. Biological samples for PKs, immunogenicity, target engagement, and PD biomarker analyses were collected. No meaningful differences in the frequencies of TEAEs were observed between the tozorakimab and placebo arms. Three tozorakimab-treated participants with COPD experienced treatment-emergent serious adverse events. Subcutaneous or intravenous tozorakimab demonstrated linear, time-independent PKs with a mean half-life of 11.7-17.3 days. Treatment-emergent anti-drug antibody frequency was low. Engagement of tozorakimab with endogenous IL-33 in serum and nasal airways was demonstrated. Tozorakimab significantly reduced serum IL-5 and IL-13 levels in patients with COPD compared with placebo. Overall, tozorakimab was well tolerated, with a linear, time-independent serum PK profile. Additionally, biomarker studies demonstrated proof of mechanism. Overall, these data support the further clinical development of tozorakimab in COPD and other inflammatory diseases.


Assuntos
Interleucina-33 , Doença Pulmonar Obstrutiva Crônica , Adulto , Humanos , Doença Pulmonar Obstrutiva Crônica/diagnóstico , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico , Anticorpos Monoclonais/efeitos adversos , Citocinas , Método Duplo-Cego , Biomarcadores , Voluntários Saudáveis
3.
Front Public Health ; 10: 984848, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36033754

RESUMO

This research study focuses on the employee's job performance of private small firms during the post COVID-19 situation. After the COVID these small family firms try to regain their business, but their efforts are not that much successful. This situation creates a financial crisis in these firms, and they are unable to provide sufficient monetary rewards to their employees. This situation creates unrest among the employees of these small firms. To manage this issue, social rewards and psychological rewards played their role. The study uses a causal research design with a correlational study design in a non-contrived environment. Minimal researcher interference has been assured. AMOS 24 has dealt with the mediation in study design with bootstrap methodology. The study was conducted on 250 employees of different private small family firms across Punjab province using a proportionate stratified sampling technique. A study's finding suggests that top management enhances employee performance in their organizations by introducing the organization's psychological rewards. In contrast, introducing social rewards does not significantly impact employee performance while considering satisfaction and motivation as a mediating variable.


Assuntos
COVID-19 , Humanos , Motivação , Satisfação Pessoal , Recompensa
4.
Front Psychol ; 13: 920112, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35874365

RESUMO

In this article, two significant elements in social media websites, system operation, and social technology are examined in connection to website visitors' online loyalty and interaction, namely, commitment and satisfaction, in neighborhood management through social media websites. A total of 287 social media users completed a systematic questionnaire. After confirmatory factor analysis, data were examined in AMOS 24 using structural equation modeling with bootstrap. The research showed that both variables indirectly influence website visitors' online loyalty and interaction via trust and satisfaction, but not directly. Online relationship quality characteristics impact the interaction pattern of social media users after changes in services applied by the respective organizations on their websites. As for managers, the research gives crucial data on user behavior in connection to new services launched by organizations on their websites and shows how value creation to the target audience may help them reduce costs and optimize revenues.

5.
Br J Clin Pharmacol ; 88(1): 260-270, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34182611

RESUMO

AIMS: This 3-part, randomised, phase 1 first-in-human study (NCT03436316) investigated the safety, tolerability and pharmacokinetics (PK) of AZD8154, a dual phosphoinositide 3-kinase (PI3K) γδ inhibitor developed as a novel inhaled anti-inflammatory treatment for respiratory disease. METHODS: Healthy men, and women of nonchildbearing potential, were enrolled to receive single and multiple ascending inhaled doses of AZD8154 in parts 1 and 3 of the study, respectively, while part 2 characterised the systemic PK after a single intravenous (IV) dose. In part 1, participants received 0.1-7.7 mg AZD8154 in 6 cohorts. In part 2, participants were given 0.15 mg AZD8154 as an IV infusion. In part 3, AZD8154 was given in 3 cohorts of 0.6, 1.8 and 3.1 mg, with a single dose on Day 1 followed by repeated once-daily doses on Days 4-12. RESULTS: In total, 78 volunteers were randomised. All single inhaled, single IV and multiple inhaled doses were shown to be well tolerated without any safety concerns. A population PK model, using nonlinear mixed-effect modelling, was developed to describe the PK of AZD8154. The terminal mean half-life of AZD8154 was 18.0-32.0 hours. The geometric mean of the absolute pulmonary bioavailability of AZD8154 via the inhaled route was 94.1%. CONCLUSION: AZD8154 demonstrated an acceptable safety profile, with no reports of serious adverse events and no clinically significant drug-associated safety concerns reported in healthy volunteers. AZD8154 demonstrated prolonged lung retention and a half-life supporting once-daily dosing.


Assuntos
Fosfatidilinositol 3-Quinases , Área Sob a Curva , Disponibilidade Biológica , Relação Dose-Resposta a Droga , Método Duplo-Cego , Feminino , Voluntários Saudáveis , Humanos , Masculino , Inibidores de Fosfoinositídeo-3 Quinase/administração & dosagem , Inibidores de Fosfoinositídeo-3 Quinase/farmacocinética
6.
Respir Med ; 191: 106705, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34879298

RESUMO

Diffusing capacity for carbon monoxide (DLCO) was measured in a phase I single ascending dose study after inhalation of AZD8154 or placebo in healthy participants at baseline (DLCOBaseline) and follow-up (DLCOFollow-up) 6 days after dosing. Initially, DLCOFollow-up timepoint was 2 h earlier than the DLCOBaseline timepoint and clinically significant decreases in DLCOFollow-up (absolute change up to 19% from baseline and DLCO%predicted values less than 70) were observed then. The observed reduction in DLCOFollow-up was confirmed as a false positive finding after alignment of DLCO timings. As a consequence, when DLCO is used in clinical studies, measurements should be strictly standardized in relation to time of the day.


Assuntos
Monóxido de Carbono , Capacidade de Difusão Pulmonar , Administração por Inalação , Ritmo Circadiano , Ensaios Clínicos como Assunto , Humanos
7.
Br J Pharmacol ; 178(22): 4440-4451, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34250588

RESUMO

BACKGROUND AND PURPOSE: Human pharmacokinetic studies of lung-targeted drugs are typically limited to measurements of systemic plasma concentrations, which provide no direct information on lung target-site concentrations. We aimed to evaluate lung pharmacokinetics of commonly prescribed drugs by sampling different lung compartments after inhalation and oral administration. EXPERIMENTAL APPROACH: Healthy volunteers received single, sequential doses of either inhaled salbutamol, salmeterol and fluticasone propionate (n = 12), or oral salbutamol and propranolol (n = 6). Each participant underwent bronchoscopies and gave breath samples for analysis of particles in exhaled air at two points after drug administration (1 and 6, 2 and 9, 3 and 12, or 4 and 18 h). Lung samples were taken via bronchosorption, bronchial brush, mucosal biopsy and bronchoalveolar lavage during each bronchoscopy. Blood samples were taken during the 24 h after administration. Pharmacokinetic profiles were generated by combining data from multiple individuals, covering all sample timings. KEY RESULTS: Pharmacokinetic profiles were obtained for each drug in lung epithelial lining fluid, lung tissue and plasma. Inhalation of salbutamol resulted in approximately 100-fold higher concentrations in lung than in plasma. Salmeterol and fluticasone concentration ratios in lung versus plasma were higher still. Bronchosorption- and bronchoalveolar-lavage-generated profiles of inhaled drugs in epithelial lining fluid were comparable. For orally administered drugs, epithelial-lining-fluid concentrations were overestimated in bronchoalveolar-lavage-generated profiles. CONCLUSION AND IMPLICATIONS: Combining pharmacokinetic data derived from several individuals and techniques sampling different lung compartments enabled generation of pharmacokinetic profiles for evaluation of lung targeting after inhaled and oral drug delivery.


Assuntos
Preparações Farmacêuticas , Albuterol , Fluticasona , Humanos , Pulmão , Xinafoato de Salmeterol
8.
Front Psychol ; 12: 627659, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33716893

RESUMO

This research focuses on the employee loyalty aspect of private hospitals in Pakistan during the COVID-19 pandemic, seriously impacted by strict work demand and work-family conflict. To manage this issue, social rewards and psychological rewards played a role as a mediator. The study uses a causal research design with a correlational study design in a non-contrived environment. Minimal researcher interference has been assured. AMOS 24 has been used to deal with the mediation in study design with bootstrap methodology. The study was conducted on 250 nurses of different private hospitals across Punjab province using a proportionate stratified sampling technique. A finding of this study suggests that nurses remain loyal to their organizations despite having uncompromising work demands and facing work-family conflict when they are provided with social and psychological rewards on their job by their organizations.

9.
BMC Pharmacol Toxicol ; 21(1): 56, 2020 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-32727574

RESUMO

BACKGROUND: This study aimed to assess the pediatric lisinopril doses using an adult physiological based pharmacokinetic (PBPK) model. As the empirical rules of dose calculation cannot calculate gender-specific pediatric doses and ignores the age-related physiological differences. METHODS: A PBPK model of lisinopril for the healthy adult population was developed for oral (fed and fasting) and IV administration using PK-Sim MoBI® and was scaled down to a virtual pediatric population for prediction of lisinopril doses in neonates to infants, infants to toddler, children at pre-school age, children at school age and the adolescents. The pharmacokinetic parameters were predicted for the above groups at decremental doses of 20 mg, 10 mg, 5 mg, 2.5 mg, and 1.5 mg in order to accomplish doses producing the pharmacokinetic parameters, similar (or comparable) to that of the adult population. The above simulated pediatric doses were compared to the doses computed using the conventional four methods, such as Young's rule, Clark's rule, and weight-based and body surface area-based equations and the dose reported in different studies. RESULTS: Though the doses predicted for all subpopulations of children were comparable to those calculated by Young's rule, yet the conventional methods overestimated the pediatric doses when compared to the respective PBPK-predicted doses. The findings of previous real time pharmacokinetic studies in pediatric patients supported the present simulated dose. CONCLUSION: Thus, PBPK seems to have predictability potential for pediatric dose since it takes into consideration the physiological changes related to age and gender.


Assuntos
Anti-Hipertensivos/administração & dosagem , Lisinopril/administração & dosagem , Modelos Biológicos , Administração Oral , Adolescente , Adulto , Anti-Hipertensivos/sangue , Anti-Hipertensivos/farmacocinética , Criança , Pré-Escolar , Simulação por Computador , Feminino , Humanos , Lactente , Recém-Nascido , Lisinopril/sangue , Lisinopril/farmacocinética , Masculino , Reprodutibilidade dos Testes , Adulto Jovem
10.
CPT Pharmacometrics Syst Pharmacol ; 9(8): 444-455, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32501650

RESUMO

AZD9567 is a potent and selective nonsteroidal oral glucocorticoid receptor modulator. It is developed as an anti-inflammatory drug with improved safety profile compared with steroids like prednisolone. Throughout the clinical development of AZD9567, dose selection and data interpretation require a method for determining doses with the same anti-inflammatory effect as prednisolone. Equipotent doses of AZD9567 and prednisolone were defined by the same average inhibition of TNFα release, a biomarker of anti-inflammatory effect, measured in a lipopolysaccharide-stimulated whole blood ex vivo assay. Based on pharmacokinetic-pharmacodynamic models, TNFα dose-response relationships for AZD9567 and prednisolone were established. A comparison of the dose-response curves enabled estimation of an equipotency relationship. Specifically, 20 mg prednisolone was estimated to be equipotent to 40 mg AZD9567 (95% confidence interval: 29-54 mg). Static concentration-response analyses showed that the relative potencies for inhibition of TNFα release of AZD9567 and prednisolone were well aligned with several other pro-inflammatory cytokines.


Assuntos
Anti-Inflamatórios/farmacologia , Indazóis/farmacologia , Modelos Biológicos , Prednisolona/farmacologia , Piridinas/farmacologia , Anti-Inflamatórios/administração & dosagem , Relação Dose-Resposta a Droga , Humanos , Indazóis/administração & dosagem , Lipopolissacarídeos , Prednisolona/administração & dosagem , Piridinas/administração & dosagem , Ensaios Clínicos Controlados Aleatórios como Assunto , Receptores de Glucocorticoides/efeitos dos fármacos , Receptores de Glucocorticoides/metabolismo , Fator de Necrose Tumoral alfa/metabolismo
11.
Front Psychol ; 11: 634375, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33569030

RESUMO

This study discusses the impact of different economic indicators on economic stability, including honest leadership, improved infrastructure, revenue generation, and CPEC taking into account the double mediating role of environmental sustainability and sustainable development, while considering the latest COVID-19 situation. This study adopted primary data collection methods and obtained data from the employees of CPEC by using questionnaires and smart-PLS for analysis purposes. The results revealed that honest leadership, improved infrastructure, revenue generation, and CPEC have a positive nexus with economic stability. Despite the severe impact of COVID-19 on the country's economy, the economic corridor plays a vital role in stabilizing the state's economy and supports all those related to this phenomenal project either directly or indirectly.

12.
Mol Ther Methods Clin Dev ; 9: 330-346, 2018 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30038937

RESUMO

mRNA can direct dose-dependent protein expression in cardiac muscle without genome integration, but to date has not been shown to improve cardiac function in a safe, clinically applicable way. Herein, we report that a purified and optimized mRNA in a biocompatible citrate-saline formulation is tissue specific, long acting, and does not stimulate an immune response. In small- and large-animal, permanent occlusion myocardial infarction models, VEGF-A 165 mRNA improves systolic ventricular function and limits myocardial damage. Following a single administration a week post-infarction in mini pigs, left ventricular ejection fraction, inotropy, and ventricular compliance improved, border zone arteriolar and capillary density increased, and myocardial fibrosis decreased at 2 months post-treatment. Purified VEGF-A mRNA establishes the feasibility of improving cardiac function in the sub-acute therapeutic window and may represent a new class of therapies for ischemic injury.

13.
PLoS One ; 10(5): e0118638, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25932627

RESUMO

It is essential to establish a useful validation method for newly generated humanized mouse models. The novel approach of combining our established species-specific protein quantification method combined with in vivo functional studies is evaluated to validate a humanized mouse model of P-gp/MDR1 efflux transporter. The P-gp substrates digoxin, verapamil and docetaxel were administered to male FVB Mdr1a/1b(+/+) (FVB WT), FVB Mdr1a/1b(-/-) (Mdr1a/1b(-/-)), C57BL/6 Mdr1a/1b(+/+) (C57BL/6 WT) and humanized C57BL (hMDR1) mice. Brain-to-plasma total concentration ratios (Kp) were measured. Quantitative targeted absolute proteomic (QTAP) analysis was used to selectively quantify the protein expression levels of hMDR1, Mdr1a and Mdr1b in the isolated brain capillaries. The protein expressions of other transporters, receptors and claudin-5 were also quantified. The Kp for digoxin, verapamil, and docetaxel were 20, 30 and 4 times higher in the Mdr1a/1b(-/-) mice than in the FVB WT controls, as expected. The Kp for digoxin, verapamil and docetaxel were 2, 16 and 2-times higher in the hMDR1 compared to the C57BL/6 WT mice. The hMDR1 mice had 63- and 9.1-fold lower expressions of the hMDR1 and Mdr1a proteins than the corresponding expression of Mdr1a in C57BL/6 WT mice, respectively. The protein expression levels of other molecules were almost consistent between C57BL/6 WT and hMDR1 mice. The P-gp function at the BBB in the hMDR1 mice was smaller than that in WT mice due to lower protein expression levels of hMDR1 and Mdr1a. The combination of QTAP and in vivo functional analyses was successfully applied to validate the humanized animal model and evaluates its suitability for further studies.


Assuntos
Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Barreira Hematoencefálica/metabolismo , Subfamília B de Transportador de Cassetes de Ligação de ATP/antagonistas & inibidores , Animais , Transporte Biológico/efeitos dos fármacos , Barreira Hematoencefálica/efeitos dos fármacos , Encéfalo/irrigação sanguínea , Encéfalo/efeitos dos fármacos , Capilares/efeitos dos fármacos , Capilares/metabolismo , Ciclosporina/farmacologia , Digoxina/metabolismo , Humanos , Proteínas de Membrana/metabolismo , Camundongos Endogâmicos C57BL , Modelos Animais , Oxicodona/metabolismo , Proteômica , Membro 4 da Subfamília B de Transportadores de Cassetes de Ligação de ATP
14.
J Pharm Sci ; 102(9): 3320-31, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23463542

RESUMO

The aim of this study was to characterize the blood-brain barrier (BBB) transport and pharmacokinetics-pharmacodynamics (PKPD) relationship of oxymorphone and to further elucidate its possible contribution to oxycodone analgesia. The BBB transport of oxymorphone was studied using microdialysis in male Sprague-Dawley rats. Samples from microdialysis blood and brain probes, brain tissue, and plasma were analyzed by liquid chromatography with tandem mass spectrometry. The effect was measured as tail-flick latency. The study consisted of a PKPD experiment with combined microdialysis and antinociceptive measurements (n = 8), and another antinociceptive effect experiment (n = 9) using a 10 times lower dose. The combined data were analyzed with an integrated PKPD model in nonlinear mixed effect modeling utilizing a specific method (M3) for handling missing PD observations. The concentration of unbound oxymorphone was higher in brain than in blood, with a ratio of 1.9 (RSE, 9.7%), indicating active uptake at the BBB. The integrated PKPD model described the oxymorphone BBB transport and PKPD relationship successfully, with an EC50 in the brain of 63 ng/mL, and the M3 method was able to address the issue of censored observations. Oxymorphone has active uptake transport at the BBB in rats, with moderate uptake clearance to the brain. Its contribution to analgesia after oxycodone administration is not significant.


Assuntos
Analgésicos Opioides/farmacologia , Analgésicos Opioides/farmacocinética , Barreira Hematoencefálica/metabolismo , Oxicodona/farmacologia , Oximorfona/farmacologia , Oximorfona/farmacocinética , Analgésicos Opioides/metabolismo , Animais , Transporte Biológico Ativo , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Masculino , Modelos Biológicos , Oximorfona/metabolismo , Ratos , Ratos Sprague-Dawley
15.
J Pharm Sci ; 100(9): 3912-23, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21472729

RESUMO

Diphenhydramine (DPHM) and oxycodone are weak bases that are able to form cations. Both drugs show active uptake at the blood-brain barrier (BBB). There is thus a possibility for a pharmacokinetic interaction between them by competition for the same uptake transport system. The experiments of the present study were designed to study the transport of DPHM across the BBB and its interaction with oxycodone in vitro and in vivo. In vitro, the interaction between the drugs was studied using conditionally immortalized rat brain capillary endothelial cells (TR-BBB13 cells). The in vivo relevance of the in vitro findings was studied in rats using brain and blood microdialysis. DPHM was actively transported across the BBB in vitro (TR-BBB13 cells). Oxycodone competitively inhibited DPHM uptake with a K(i) value of 106 µM. DPHM also competitively inhibited oxycodone uptake with a K(i) value of 34.7 µM. In rats, DPHM showed fivefold higher unbound concentration in brain interstitial fluid (ISF) than in blood, confirming a net active uptake. There was no significant interaction between DPHM and oxycodone in vivo. This accords with the results of the in vitro experiments because the unbound plasma concentrations that could be attained in vivo, without causing adverse effects, were far below the K(i) values.


Assuntos
Barreira Hematoencefálica , Difenidramina/farmacocinética , Antagonistas dos Receptores Histamínicos H1/farmacocinética , Oxicodona/farmacologia , Animais , Linhagem Celular Transformada , Cromatografia Líquida , Difenidramina/farmacologia , Interações Medicamentosas , Endotélio Vascular/citologia , Endotélio Vascular/metabolismo , Antagonistas dos Receptores Histamínicos H1/farmacologia , Técnicas In Vitro , Masculino , Espectrometria de Massas , Controle de Qualidade , Ratos , Ratos Sprague-Dawley , Padrões de Referência
16.
Drug Metab Dispos ; 39(2): 174-9, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21059857

RESUMO

Morphine has been predicted to show nonlinear blood-brain barrier transport at lower concentrations. In this study, we investigated the possibility of separating active influx of morphine from its efflux by using very low morphine concentrations and compared accelerator mass spectrometry (AMS) with liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a method for analyzing microdialysis samples. A 10-min bolus infusion of morphine, followed by a constant-rate infusion, was given to male rats (n = 6) to achieve high (250 ng/ml), medium (50 ng/ml), and low (10 ng/ml) steady-state plasma concentrations. An additional rat received infusions to achieve low (10 ng/ml), very low (2 ng/ml), and ultralow (0.4 ng/ml) concentrations. Unbound morphine concentrations from brain extracellular fluid and blood were sampled by microdialysis and analyzed by LC-MS/MS and AMS. The average partition coefficient for unbound drug (K(p,uu)) values for the low and medium steady-state levels were 0.22 ± 0.08 and 0.21 ± 0.05, respectively, when measured by AMS [not significant (NS); p = 0.5]. For the medium and high steady-state levels, K(p,uu) values were 0.24 ± 0.05 and 0.26 ± 0.05, respectively, when measured by LC-MS/MS (NS; p = 0.2). For the low, very low, and ultralow steady-state levels, K(p,uu) values were 0.16 ± 0.01, 0.16 ± 0.02, and 0.18 ± 0.03, respectively, when measured by AMS. The medium-concentration K(p,uu) values were, on average, 16% lower when measured by AMS than by LC-MS/MS. There were no significant changes in K(p,uu) over a 625-fold concentration range (0.4-250 ng/ml). It was not possible to separate active uptake transport from active efflux using these low concentrations. The two analytical methods provided indistinguishable results for plasma concentrations but differed by up to 38% for microdialysis samples; however, this difference did not affect our conclusions.


Assuntos
Barreira Hematoencefálica/metabolismo , Cromatografia Líquida/métodos , Morfina/farmacocinética , Espectrometria de Massas por Ionização por Electrospray/métodos , Espectrometria de Massas em Tandem/métodos , Animais , Transporte Biológico , Radioisótopos de Carbono , Relação Dose-Resposta a Droga , Infusões Intravenosas , Masculino , Microdiálise , Morfina/administração & dosagem , Morfina/sangue , Ratos , Ratos Sprague-Dawley
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