Changes in liver volume from birth to adulthood: A meta-analysis

Johnson, Trevor N.; Tucker, Geoffrey T.; Tanner, M S; Rostami‐Hodjegan, Amin

doi:10.1002/lt.20519

Cited by 282 publications

(240 citation statements)

References 37 publications

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“…The allometric size model of CL varying with W 3/4 was originally based on the observation that basal metabolic rate scales with W 3/4 across species [27], but another potential justification is that liver size also appears to change with W 3/4 [28]. Diclofenac is extensively metabolized in the liver, and this study found that diclofenac CL could adequately be described by scaling estimates to W 3/4 over a 10-fold weight range.…”

Section: Discussionmentioning

confidence: 76%

Population pharmacokinetics of oral diclofenac for acute pain in children

Standing

Howard

Johnson

et al. 2008

Brit J Clinical Pharma

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WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Diclofenac is an effective oral analgesic for acute postoperative pain. In adults 25 mg is half as effective as 50 mg, but 50 mg and 100 mg are similarly effective (ceiling effect). Diclofenac has linear pharmacokinetics in this range.• Diclofenac is frequently used 'off-label' in children for acute pain but optimum dosing is unclear (dosing of diclofenac in clinical paediatric studies ranges from 0.5-2.5 mg kg -1 ). There is currently no licensed oral paediatric formulation of diclofenac. WHAT THIS STUDY ADDS• Using a new diclofenac oral suspension, a dose of 1 mg kg -1 in children aged 1 to 12 years gives a similar exposure to 50 mg in adults; paediatric patients are unlikely to benefit from higher doses. AIMSTo develop a population pharmacokinetic model for a new diclofenac suspension (50 mg 5 ml -1 ) in adult volunteers and paediatric patients, and recommend a dose for acute pain in children. METHODSBlood samples were drawn at the start and end of surgery, and on removal of the venous cannula from 70 children (aged 1 to 12 years, weight 9 to 37 kg) who received a preoperative oral 1 mg kg -1 dose; these were pooled with rich (14 post-dose samples) data from 30 adult volunteers. Population pharmacokinetic modelling was undertaken with NONMEM. The optimum adult dose of diclofenac for acute pain is 50 mg. Simulation from the final model was performed to predict a paediatric dose to achieve a similar AUC to 50 mg in adults. RESULTSA total of 558 serum diclofenac concentrations from 100 subjects was used in the pooled analysis. A single disposition compartment model with first order elimination and dual absorption compartments was used. The estimates of CL/F and VD/F were 53.98 l h -1 70 kg -1 and 4.84 l 70 kg -1 respectively. Allometric size models appeared to predict adequately changes in CL and VD with age. Of the simulated doses investigated, 1 mg kg -1 gave paediatric AUC(0,12 h) to adult 50 mg AUC(0,12 h) ratios of 1.00, 1.08 and 1.18 for ages 1-3, 4-6 and 7-12 years respectively. CONCLUSIONSThis study has shown 1 mg kg -1 diclofenac to produce similar exposure in children aged 1 to 12 years as 50 mg in adults, and is acceptable for clinical practice; patients are unlikely to obtain further benefit from higher doses.

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Section: Discussionmentioning

confidence: 76%

Population pharmacokinetics of oral diclofenac for acute pain in children

Standing

Howard

Johnson

et al. 2008

Brit J Clinical Pharma

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“…In this calculation, 1,736.96 g of liver weight21 and 126.27 million cells/g liver22 were used as representative values of healthy volunteers.…”

Section: Methodsmentioning

confidence: 99%

Using a Vancomycin PBPK Model in Special Populations to Elucidate Case‐Based Clinical PK Observations

Emoto

Johnson

McPhail

et al. 2018

CPT Pharmacom & Syst Pharma

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Simultaneous changes in several physiological factors may contribute to the large pharmacokinetic (PK) variability of vancomycin. This study was designed to systematically characterize the effects of multiple physiological factors to the altered PK of vancomycin observed in special populations. A vancomycin physiologically based pharmacokinetic (PBPK) model was developed as a PK simulation platform to quantitatively assess the effects of changes in physiologies to the PK profiles. The developed model predicted the concentration‐time profiles in healthy adults and diseased patients. The implementation of developmental changes in both renal and non‐renal elimination pathways to the pediatric model improved the predictability of vancomycin clearance. Simulated PK profiles with a 50% decrease in cardiac output (peak plasma concentration (Cmax), 59.9 ng/mL) were similar to those observed in patients before bypass surgery (Cmax, 55.1 ng/mL). The PBPK modeling of vancomycin demonstrated its potential to provide mechanistic insights into the altered disposition observed in patients who have changes in multiple physiological factors.

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“…Several studies have investigated the estimation of liver size using mathematical formulas to estimate liver volume. [3][4][5][6] However, these formulas were based on the patient's body surface area, body weight, body length, sex, age, and/or race. Standard errors (SE) in the range of 275 to 328 mL were found.…”

Section: Abstract: Density Formula Volumementioning

confidence: 99%

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Sonnemans

Hol²,

Monshouwer³

et al. 2016

Exp Clin Transplant

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Objectives: Before liver transplant, it is necessary to know the size of the organ in advance of the procedure. We studied the correlation between liver volumetric computed tomography results and liver weight. Materials and Methods: Postmortem volumetric computed tomography was conducted on cadavers before autopsy, and 3-dimensional liver volume was estimated with semiautomated software. Liver weight was then determined at autopsy. Linear regression and univariate analysis of variance results were used to determine the accuracy of volumetric 3-dimensional computed tomography in estimating liver weight. We also used 2-dimensional liver sizes to design a 2-dimensional formula to estimate liver volume. Results: We found that 3-dimensional volumetric computed tomography was able to accurately estimate liver weight (standard error = 157 g) with a liver density of 0.99 g/mL. Intraobserver and interobserver variabilities were small. The 2-dimensional formula estimated liver weight slightly less accurately (standard error = 212 g). Conclusions: We conclude that liver weight can be estimated accurately with 3-dimensional volumetric computed tomography; estimates were more precise than with the 2-dimensional formula-based liver volume estimation. Volumetric computed tomography can be an important tool during preoperative workup before transplant surgery. Key words: Density, Formula, VolumeIntroduction Liver transplant requires a precise workup of both the donor's and recipient's liver, including evaluation of liver anatomy, parenchyma, vascular supply, and volume. The preoperative assessment of liver volume can be crucial for transplant success. The recipient needs a future liver remnant volume of at least about 30% of the standard liver size. 1,2 In addition, a liver size of about 30% must be preserved in a healthy living donor for survival. Several studies have investigated the estimation of liver size using mathematical formulas to estimate liver volume. [3][4][5][6] However, these formulas were based on the patient's body surface area, body weight, body length, sex, age, and/or race. Standard errors (SE) in the range of 275 to 328 mL were found. Because liver size and shape vary widely between individuals, it may be difficult, if not impossible, to apply estimation formulas with parameters that are based on the body versus the liver.State-of-the-art transplant surgery necessitates imaging of the liver and its vascular supply, which is usually performed with contrast-enhanced computed tomography (CT) or magnetic resonance imaging. Therefore, most donors and recipients of liver transplant have a preoperative CT or magnetic resonance imaging scan. During the past decade, hepatic volumetry and 3-dimensional imaging techniques with CT have been introduced to increase the precision and safety of liver surgery. 7

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Changes in liver volume from birth to adulthood: A meta-analysis

Cited by 282 publications

References 37 publications

Population pharmacokinetics of oral diclofenac for acute pain in children

Population pharmacokinetics of oral diclofenac for acute pain in children

Using a Vancomycin PBPK Model in Special Populations to Elucidate Case‐Based Clinical PK Observations

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