RESUMO
PURPOSE: Currently, body weight-based dosing of rifampicin is recommended. But lately, fat-free mass (FFM) was reported to be superior to body weight (BW). The present evaluation aimed to assess the influence of body mass-related covariates on rifampicin's pharmacokinetics (PK) parameters in more detail using non-linear mixed effects modeling (NLMEM). METHODS: Twenty-four healthy Caucasian volunteers were enrolled in a bioequivalence study, each receiving a test and a reference tablet of 600 mg of rifampicin separated by a wash-out period of at least 9 days. Monolix version 2023R1 was used for NLMEM. Monte Carlo simulations (MCS) were performed to visualize the relationship of body size descriptors to the exposure to rifampicin. RESULTS: A one-compartment model with nonlinear (Michaelis-Menten) elimination and zero-order absorption kinetics with a lag time best described the data. The covariate model including fat-free mass (FFM) on volume of distribution (V/F) and on maximum elimination rate (Vmax/F) lowered the objective function value (OFV) by 56.4. The second-best covariate model of sex on V/F and Vmax/F and BW on V/F reduced the OFV by 51.2. The decrease in unexplained inter-individual variability on Vmax/F in both covariate models was similar. For a given dose, MCS showed lower exposure to rifampicin with higher FFM and accordingly in males compared to females with the same BW and body height. CONCLUSION: Our results indicate that beyond BW, body composition as reflected by FFM could also be relevant for optimized dosing of rifampicin. This assumption needs to be studied further in patients treated with rifampicin.
Assuntos
Voluntários Saudáveis , Modelos Biológicos , Rifampina , População Branca , Humanos , Rifampina/farmacocinética , Rifampina/administração & dosagem , Masculino , Feminino , Adulto , Adulto Jovem , Equivalência Terapêutica , Método de Monte Carlo , Antibióticos Antituberculose/farmacocinética , Antibióticos Antituberculose/administração & dosagem , Peso Corporal , Estudos Cross-Over , Dinâmica não LinearRESUMO
A new probe drug cocktail containing substrates of important drug transporters was tested for mutual interactions in a clinical trial. The cocktail consisted of (predominant transporter; primary phenotyping metric): 10 mg adefovir-dipivoxil (OAT1; renal clearance (CLR )), 100 mg sitagliptin (OAT3; CLR ), 500 mg metformin (several renal transporters; CLR ), 2 mg pitavastatin (OATP1B1; clearance/F), and 0.5 mg digoxin (intestinal P-gp, renal P-gp, and OATP4C1; peak plasma concentration (Cmax ) and CLR ). Using a randomized six-period, open change-over design, single oral doses were administrated either concomitantly or separately to 24 healthy male and female volunteers. Phenotyping metrics were evaluated by noncompartmental analysis and compared between periods by the standard average bioequivalence approach (boundaries for ratios 0.80-1.25). Primary metrics supported the absence of relevant interactions, whereas secondary metrics suggested that mainly adefovir was a victim of minor drug-drug interactions (DDIs). All drugs were well tolerated. This cocktail may be another useful tool to assess transporter-based DDIs in vivo.
Assuntos
Adenina/análogos & derivados , Digoxina/farmacocinética , Metformina/farmacocinética , Organofosfonatos/farmacocinética , Quinolinas/farmacocinética , Fosfato de Sitagliptina/farmacocinética , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Adenina/farmacocinética , Adulto , Interações Medicamentosas , Feminino , Genótipo , Voluntários Saudáveis , Humanos , Transportador 1 de Ânion Orgânico Específico do Fígado/genética , Transportador 1 de Ânion Orgânico Específico do Fígado/metabolismo , Masculino , Pessoa de Meia-Idade , Fator 1 de Transcrição de Octâmero/genética , Fator 1 de Transcrição de Octâmero/metabolismo , Proteína 1 Transportadora de Ânions Orgânicos/genética , Proteína 1 Transportadora de Ânions Orgânicos/metabolismo , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/metabolismo , Transportadores de Ânions Orgânicos Sódio-Independentes/genética , Transportadores de Ânions Orgânicos Sódio-Independentes/metabolismoAssuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP , Barreira Hematoencefálica , Subfamília B de Transportador de Cassetes de Ligação de ATP , Citocromo P-450 CYP1A2 , Citocromo P-450 CYP2C19 , Citocromo P-450 CYP2C9 , Citocromo P-450 CYP2D6 , Citocromo P-450 CYP3A , Etanol , Metoclopramida , Tomografia por Emissão de PósitronsRESUMO
We quantified the effect of acute ethanol exposure (initial blood concentrations 0.7 g/L) on major drug metabolizing enzymes and p-glycoprotein. Sixteen healthy Caucasians participated in a randomized crossover study with repeated administration of either vodka or water. Enzyme/transporter activity was assessed by a cocktail of probe substrates, including caffeine (CYP1A2/NAT2), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), midazolam (CYP3A), and digoxin (P-glycoprotein). The ratio of AUC0-t of dextromethorphan for ethanol/water coadministration was 1.95 (90% confidence interval (CI) 1.48-2.58). The effect was strongest in individuals with a CYP2D6 genotype predicting high activity (n = 7, ratio 2.66, 90% CI 1.65-4.27). Ethanol increased caffeine AUC0-t 1.38-fold (90% CI 1.25-1.52) and reduced intestinal midazolam extraction 0.77-fold (90% CI 0.69-0.86). The other probe drugs were not affected by ethanol. The results suggest that acute ethanol intake typically has no clinically important effect on the enzymes/transporters tested.
Assuntos
Consumo de Bebidas Alcoólicas/metabolismo , Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP2D6/metabolismo , Citocromo P-450 CYP3A/metabolismo , Inibidores das Enzimas do Citocromo P-450/administração & dosagem , Etanol/administração & dosagem , Intestinos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Adulto , Consumo de Bebidas Alcoólicas/efeitos adversos , Arilamina N-Acetiltransferase/metabolismo , Estudos Cross-Over , Citocromo P-450 CYP1A2/genética , Inibidores do Citocromo P-450 CYP1A2/administração & dosagem , Citocromo P-450 CYP2C19/metabolismo , Citocromo P-450 CYP2C9/metabolismo , Citocromo P-450 CYP2D6/genética , Inibidores do Citocromo P-450 CYP2D6/administração & dosagem , Citocromo P-450 CYP3A/genética , Inibidores do Citocromo P-450 CYP3A/administração & dosagem , Inibidores das Enzimas do Citocromo P-450/efeitos adversos , Etanol/efeitos adversos , Feminino , Genótipo , Humanos , Intestinos/enzimologia , Fígado/enzimologia , Masculino , Farmacocinética , Fenótipo , Medição de Risco , Especificidade por Substrato , Adulto JovemRESUMO
PURPOSE: The combination of magnetic nanoparticles (MNPs) with a magnetic field is a powerful approach to enable cell positioning and/or local gene therapy. Because physical requirements for MNPs differ between these two applications we have explored whether the use of different MNPs can provide site-specific positioning combined with efficient viral transduction of endothelial cells (ECs). METHODS: A variety of MNPs was screened for magnetic cell labeling and lentivirus binding. Then two different MNPs were chosen and their combined application was evaluated regarding EC magnetization and transduction efficiency. RESULTS: The combined use of PEI-Mag2 and NDT-Mag1 particles provided both efficient lentiviral transduction and high magnetic responsiveness of ECs that could be even retained within the vascular wall under flow conditions. The use of these MNPs did not affect biological characteristics of ECs like surface marker expression and vascular network formation. Importantly, with this method we could achieve an efficient functional overexpression of endothelial nitric oxide synthase in ECs. CONCLUSIONS: The application of two different MNPs provides optimal results for magnetic labeling of ECs in combination with viral transduction. This novel approach could be very useful for targeted gene therapy ex vivo and site-specific cell replacement in the vascular system.
Assuntos
Células Endoteliais/metabolismo , Lentivirus/genética , Magnetismo , Nanopartículas/química , Transdução Genética , Animais , Western Blotting , Bovinos , Células Cultivadas , Feminino , Terapia Genética , Imuno-Histoquímica , Camundongos , Reação em Cadeia da PolimeraseRESUMO
PURPOSE: Targeting of specific cells and tissues is of great interest for clinical relevant gene- and cell-based therapies. We use magnetic nanoparticles (MNPs) with a ferrimagnetic core (Fe(3)O(4)) with different coatings to optimize MNP-assisted lentiviral gene transfer with focus on different endothelial cell lines. METHODS: Lentiviral vector (LV)/MNP binding was characterized for various MNPs by different methods (e.g. magnetic responsiveness measurement). Transduced cells were analyzed by flow cytometry, fluorescence microscopy and iron recovery. Cell transduction and cell positioning under physiological flow conditions were performed using different in vitro and ex vivo systems. RESULTS: Analysis of diverse MNPs with different coatings resulted in identification of nanoparticles with improved LV association and enhanced transduction properties of complexes in several endothelial cell lines. The magnetic moments of LV/MNP complexes are high enough to achieve local gene targeting of perfused endothelial cells. Perfusion of a mouse aorta with LV/MNP transduced cells under clinically relevant flow conditions led to local cell attachment at the intima of the vessel. CONCLUSION: MNP-guided lentiviral transduction of endothelial cells can be significantly enhanced and localized by using optimized MNPs.
Assuntos
Células Endoteliais/metabolismo , Técnicas de Transferência de Genes , Lentivirus/genética , Magnetismo , Nanopartículas , Animais , Bovinos , Linhagem Celular , Sobrevivência Celular , Relação Dose-Resposta a Droga , Vetores Genéticos/genética , Humanos , Camundongos , TransgenesRESUMO
PURPOSE: Magnetic nanoparticles (MNPs) and magnets can be used to enhance gene transfer or cell attachment but gene or cell delivery to confined areas has not been addressed. We therefore searched for an optimal method to simulate and perform local gene targeting and cell delivery in vitro. METHODS: Localized gene transfer or cell positioning was achieved using permanent magnets with newly designed soft iron tips and MNP/lentivirus complexes or MNP-loaded cells, respectively. Their distribution was simulated with a mathematical model calculating magnetic flux density gradients and particle trajectories. RESULTS: Soft iron tips generated strong confined magnetic fields and could be reliably used for local (~500 µm diameter) gene targeting and positioning of bone marrow cells or cardiomyocytes. The calculated distribution of MNP/lentivirus complexes and MNP-loaded cells concurred very well with the experimental results of local gene expression and cell attachment, respectively. CONCLUSION: MNP-based gene targeting and cell positioning can be reliably performed in vitro using magnetic soft iron tips, and computer simulations are effective methods to predict and optimize experimental results.