Mean Time Parameters in Pharmacokinetics

Veng‐Pedersen, Peter

doi:10.2165/00003088-198917060-00005

Cited by 55 publications

(10 citation statements)

References 36 publications

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“…Their mean age was 7.6 years (range, [3][4][5][6][7][8][9][10][11][12][13][14], and their weights ranged from 2.5 to 75 kg. Their mean age was 7.6 years (range, [3][4][5][6][7][8][9][10][11][12][13][14], and their weights ranged from 2.5 to 75 kg.…”

Section: Dogsmentioning

confidence: 99%

The Relationship between Some Plasma Clearance Methods for Estimation of Glomerular Filtration Rate in Dogs with Pyometra

Heiene

Moe

1999

J Vet Int Med

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The purpose of the present study was to compare different pharmacokinetic models for estimation of glomerular filtration rate (GFR) in 50 dogs with pyometra. GFR was estimated by plasma clearance (CLplasma) of iohexol by four 1-compartment methods (CL1c), a 2-compartment method (CL2c), and the trapezoidal method (CLtr). Regression analysis was performed to establish correction formulas for prediction of CLtr from the CL1c values and to find optimal times of sampling. Standardization of clearance values to body weight (kg), body surface area (m2) and extracellular fluid volume (ECFV) was compared by ranking of values. CLtr and CL2c values were similar, whereas CL1c overestimated CLtr. CLtr could be predicted from 2 samples at 2 and 3 hours after injection, using the formula CLtr = 4.52 + 0.84CL1c - 0.00080(CL1c)2 (R2 = .97). Similar relationships were found when sampling at 2 and 4 hours or at 2, 3 and 4 hours after injection, whereas predictions from the 3- and 4-hour estimates were not optimal (R2 = .79). The 2-sample methods for calculating GFR/ECFV generally produced unreliable predictions of the complete curve GFR/ECFV values. For some dogs, the choice of standardization procedure substantially changed the apparent level of renal function relative to other dogs in the study. We conclude that by applying an appropriate correction formula, GFR may be estimated using 2 blood samples at 2 and 3, or 2 and 4 hours after injection of iohexol when renal function is normal or moderately reduced. The method of standardizing the analysis with respect to body size may influence interpretation of the results substantially.

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Section: Dogsmentioning

confidence: 99%

The Relationship between Some Plasma Clearance Methods for Estimation of Glomerular Filtration Rate in Dogs with Pyometra

Heiene

Moe

1999

J Vet Int Med

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“…T h e metabolite forming constant kf was calculated by the method of residuals (option 5 of the INDEPEND computer program). Pharmacokinetic parameters were subsequently derived from these values according to accepted formulae (Yamaoka el al., 1978;Gibaldi & Perrier, 1982;Gouyette, 1983;Veng-Pedersen, 1989).…”

Section: Pharmacokinetic Analysismentioning

confidence: 99%

Pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin after intravenous and oral administration of enrofloxacin in dogs

Küng

Riond

Wanner

1993

Vet Pharm & Therapeutics

124

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Four dogs were given 5 mg/kg body weight enrofloxacin intravenously (i.v.) and orally (p.o.) in a cross-over study. Plasma concentrations of the active ingredient enrofloxacin and its main metabolite ciprofloxacin were determined by a reversed phase liquid chromatographic method. Pharmacokinetic parameters of both substances were calculated by use of statistical moments and were compared to those of enrofloxacin described in the veterinary literature. Mean enrofloxacin t1/2 lambda z was 2.4 h, mean Cls was 27.1 ml/min.kg, and mean Vss was 7.0 l/kg. After i.v. and p.o. administration, concentrations of ciprofloxacin exceeding minimal inhibitory concentrations of several microorganisms were reached (Cmax = 0.2 microgram/ml, tmax = 2.2 h after intravenous administration; Cmax = 0.2 microgram/ml, tmax = 3.6 h after oral administration). A considerable part of the antimicrobial activity is due to ciprofloxacin, the main metabolite of enrofloxacin.

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“…It is visualized in Figure 2 as a tangent to response intersecting the baseline at t=0 (Buffham and Kropholler, 1973). In specified settings it is a measure of the rate of elimination of a xenobiotic (Karol, 1990; Veng-Pedersen, 1989a; Veng-Pedersen, 1989b). In our scenario the parameter MT reflects the rate at which the body of the child handles PCB 153 reflecting a large scale of mechanisms, including increasing fat content.…”

Section: Discussionmentioning

confidence: 99%

Assessment of exposure to PCB 153 from breast feeding and normal food intake in individual children using a system approach model

et al. 2011

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Investigators have typically relied on a single or few discrete time points as measures of polychlorinated biphenyl (PCB) body burden, however health effects are more likely to be the result of integrative exposure in time, optionally expressed as an area under the time curve (AUC) of PCB serum concentration. Using data from a subgroup of 93 infants from a birth cohort in eastern Slovakia—a region highly polluted by PCBs—we fit a system type model, customized to our longitudinal measures of serum PCB concentrations in cord, 6, 16, and, 45 month blood specimens. The most abundant congener, PCB 153, was chosen for modeling purposes. In addition to currently used methods of exposure assessment, our approach estimates a concentration time profile for each subject, taking into account mean residence time of PCB 153 molecules in the body, duration of breast feeding, hypothetical PCB 153 concentration in steady-state without breast feeding and alternately without normal food intake. Hypothetical PCB 153 concentration in steady-state without normal food intake correlates with AUC (r=0.84, p<0.001) as well as with duration of breast feeding (r=0.64, p<0.001). It makes possible to determine each subject’s exposure profile expressed as AUC of PCBs serum concentration with a minimum model parameters. PCB body burden in most infants was strongly associated with duration of breast feeding in most, but not all children, was apparent from model output.

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Mean Time Parameters in Pharmacokinetics

Cited by 55 publications

References 36 publications

The Relationship between Some Plasma Clearance Methods for Estimation of Glomerular Filtration Rate in Dogs with Pyometra

The Relationship between Some Plasma Clearance Methods for Estimation of Glomerular Filtration Rate in Dogs with Pyometra

Pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin after intravenous and oral administration of enrofloxacin in dogs

Assessment of exposure to PCB 153 from breast feeding and normal food intake in individual children using a system approach model

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