Determination of Mean Residence Time of Drug in Plasma and the Influence of the Initial Drug Elimination and Distribution on the Calculation of Pharmacokinetic Parameters

2009 ◽  
Vol 98 (2) ◽  
pp. 748-762 ◽  
Author(s):  
Leonid M. Berezhkovskiy
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Pharmacokinetic Parameters ◽  
Drug Elimination ◽  
Initial Drug

Precipitation and filtration of zinc, magnesium, copper and aluminium hydroxides

1982 ◽  
Vol 47 (12) ◽  
pp. 3362-3370
Author(s):  
Otakar Söhnel ◽  
Eva Matějčková
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Filtration Resistance ◽  
Filtration Pressure ◽  
Bed Porosity ◽  
The Mean ◽  
Filtration Properties

Filtration properties of batchwise precipitated suspensions of Zn(OH)2, Mg(OH)2 and Cu(OH)2 and continuously precipitated Al(OH)3 were studied. For batchwise precipitated suspensions was verified the theoretically predicted dependence of specific filtration resistance on initial supersaturation and for the continuously precipitated Al(OH)3 the relation between the specific filtration resistance and the mean residence time of suspension in the reactor. Dependences were also recorded between the bed porosity and concentration of precipitated solutions, specific filtration resistance and used filtration pressure and the effect of aging of the batchwise precipitated suspension of Mg(OH)2on its filtration properties. The used CST method for determination of filtration characteristics of Zn(OH)2 suspension was also studied.

Modelling of Flow of a Liquid in Apparatus with Mobile Packing: Dispersion Model

1993 ◽  
Vol 58 (9) ◽  
pp. 2047-2058
Author(s):  
Zdeněk Palatý
Keyword(s):  
Differential Equation ◽  
Numerical Integration ◽  
Residence Time ◽  
Mean Residence Time ◽  
Peclet Number ◽  
Dispersion Model ◽  
Tracer Concentration ◽  
Optimization Of Parameters ◽  
Determination Of Parameters

The paper deals with determination of parameters of a dispersion model used for describing the flow of liquid on a plate with mobile packing in the region of gas velocities up to 1.5 m s-1. The parameters of the model - the diffusion Peclet number and mean residence time of liquid - were determined from the nonideal input impulse of tracer concentration and its response by the method of numerical integration of differential equation with subsequent optimization of parameters. The results of measurements are presented graphically and in the form of criterion equations.

scholarly journals Physiologically Based Structure of Mean Residence Time

2012 ◽  
Vol 2012 ◽  
pp. 1-4
Author(s):  
Mária Ďurišová
Keyword(s):  
Pharmacokinetic Parameter ◽  
Residence Time ◽  
Dynamic Systems ◽  
Mean Residence Time ◽  
Structural Identification ◽  
Linear Dynamic Systems ◽  
Linear Dynamic ◽  
Physiologically Based

A mean residence time (MRT) is an important pharmacokinetic parameter. To the author's knowledge, however, a physiologically based structure of MRT (thereafter MRT structure) has not been published so far. Primarily this is because MRT structures cannot be identified by traditional pharmacokinetic methods used for the determination of MRT. Therefore, tools from the theory of linear dynamic systems were used for the structural identification of MRT in this study. The MRT structure identified is physiologically meaningful. Accordingly, it seems that the MRT structure identified may contribute to already established knowledge about MRT.

scholarly journals ALTERATION OF PHARMACOKINETIC PARAMETERS OF PROTON PUMP INHIBITORS USING TRANSDERMAL DRUG DELIVERY SYSTEM

2021 ◽  
pp. 371-375
Author(s):  
M. R. SHIVALINGAM ◽  
ARUL BALASUBRAMANIAN ◽  
KOTHAI RAMALINGAM
Keyword(s):  
Plasma Concentration ◽  
Residence Time ◽  
Proton Pump ◽  
Drug Concentration ◽  
Mean Residence Time ◽  
Fold Increase ◽  
Plasma Drug Concentration ◽  
Pharmacokinetic Parameters ◽  
Plasma Drug ◽  
Transdermal Patches

Objective: The present study was aimed to find out the effect of transdermal patches of proton pump inhibitors pantoprazole and esomeprazole on the alteration of pharmacokinetic parameters of these drugs. Methods: The transdermal patches were formulated by the solvent evaporation technique using polymers HPMC E5 with PVP K 30 and HPMC E5 with Eudragit L100 in different ratios. The best formulation from each of the drug pantoprazole and esomeprazole was selected and administered to rabbits and the plasma drug concentration was compared with the marketed formulation. The pharmacokinetic parameters such as maximum plasma concentration (Cmax), time to reach Cmax (tmax), area under the curve (AUC), area under first moment curve (AUMC), elimination rate constant (λz), biological half-life (t1/2), and mean residence time (MRT) were determined. Results: The plasma drug concentration vs time curve shows the extended-release of the drugs pantoprazole and esomeprazole when compared with the marketed formulation. The results show that there is no change in the peak plasma concentration, but a significant difference was observed in all the pharmacokinetic parameters. The AUC showed 6 fold increase for pantoprazole from 8.91 to 55.20 μg*h/ml and 3.5 fold increase for the drug esomeprazole from 7.86 to 28.53 μg*h/ml, and the mean residence time also showed 2 fold increase for the transdermal patches when compared with the marketed formulations. Conclusion: The increase in tmax, AUC, and MRT values of the formulated transdermal patches with the values of the marketed formulation of both the drugs, revealed that the transdermal patches can be used to deliver the drug for an extended period and also can alter the pharmacokinetics of pantoprazole and esomeprazole.

scholarly journals Comparative Pharmacokinetic Study of Taxifolin after Oral Administration of Fructus Polygoni Orientalis Extract in Normal and Fibrotic Rats by UPLC-MS/MS

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Feili Wei ◽  
Li Guo ◽  
Yongsong Xu ◽  
Dexi Chen ◽  
Muxin Gong
Keyword(s):  
Liver Fibrosis ◽  
Oral Administration ◽  
Residence Time ◽  
Mean Residence Time ◽  
Internal Standard ◽  
Rat Plasma ◽  
Pharmacokinetic Parameters ◽  
Porcine Serum ◽  
Validation Parameters ◽  
The Mean

Fructus polygoni orientalis (FPO) is widely used in clinical practice in China, especially in treatment of liver diseases including viral hepatitis, liver fibrosis, and liver cirrhosis. However, its pharmacokinetic (PK) alterations in liver fibrotic rats have rarely been reported. To study whether taxifolin, one of the main flavonoids in FPO can be absorbed into blood after oral administration of FPO extract and to compare the differences in pharmacokinetic parameters of taxifolin to normal and liver fibrotic rats induced by porcine serum (PS), a UPLC-MS/MS method was developed and validated for determination of taxifolin in rat plasma using puerarin as the internal standard (IS). All validation parameters met the acceptance criteria according to regulatory guidelines. The results indicated that after treatment of rats with PS alone for 12 weeks, the liver fibrotic model group was built successfully. The taxifolin can be absorbed into the blood after oral administration of the FPO extract. The Cmax of taxifolin was 1940 ± 502.2 ng/mL and 2648 ± 208.5 ng/mL (p<0.05), the AUC0∼t of taxifolin was 4949.7 ± 764.89 h·ng/mL and 6679.9 ± 734.26 h·ng/mL (p<0.05), the AUC0∼∞ of taxifolin was 5049.4 ± 760.7 and 7095.2 ± 962.3 h·ng/mL (p<0.05), and the mean residence time (MRT) of taxifolin was 2.46 ± 0.412 h and 3.17 ± 0.039 h (p<0.05) in the normal and fibrotic model groups, respectively. These results confirmed that the pharmacokinetic parameters of taxifolin are altered in liver fibrosis, manifested as Cmax, AUC0∼t, AUC0∼∞, and the mean residence time (MRT). It suggested that it is essential to consider the characteristics of pharmacokinetics after oral administration of FPO in liver disease patients.

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