A Pharmacokinetic Standard for Babies and Adults

Holford, Nicholas H. G.; Heo, Young-A; Anderson, Brian J.

doi:10.1002/jps.23574

Cited by 310 publications

(410 citation statements)

References 133 publications

(146 reference statements)

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“…Parameters were normalized a priori to a body weight of 70 kg using the 3/4 rule. 18 The allometric exponents could not be estimated, as this resulted in unstable models (nonconvergence in the iterative process), probably due to the small range of weight in the population.…”

Section: Pharmacokinetic Model Buildingmentioning

confidence: 99%

“…MOF was considered to be present if a patient had renal or liver function failure as described by Shah et al 39 Maturation models (sigmoid E max functions and sigmoid hyperbolic functions) were tested to evaluate the effect of maturation of organ function on the parameter estimates. 18,40 In a stepwise fashion the significance of covariates was tested. 38 In the forward inclusion a P value of < 0.05 was applied (a decrease in OFV of at least 3.9 points, df 5 1), while a more stringent P value of <0.001 was used in the backward deletion (a decrease in the OFV of at least 10.3 points, df 5 1).…”

Section: Structural Modelmentioning

confidence: 99%

See 1 more Smart Citation

Population Pharmacokinetics of Amoxicillin in Term Neonates Undergoing Moderate Hypothermia

Bijleveld

Mathôt

Lee

et al. 2017

Clin Pharma and Therapeutics

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The pharmacokinetics (PK) of amoxicillin in asphyxiated newborns undergoing moderate hypothermia were quantified using prospective data (N 5 125). The population PK was described by a 2-compartment model with a priori birthweight (BW) based allometric scaling. Significant correlations were observed between clearance (Cl) and postnatal age (PNA), gestational age (GA), body temperature (TEMP), and urine output (UO). For a typical patient with GA 40 weeks, BW 3,000 g, 2 days PNA (i.e., TEMP 33.58C), and normal UO, Cl was 0.26 L/h (interindividual variability (IIV) 41.9%) and volume of distribution of the central compartment was 0.34 L/kg (IIV of 114.6%). For this patient, Cl increased to 0.41 L/h at PNA 5 days and TEMP 37.08C. The respective contributions of both covariates were 23% and 27%. Based on Monte Carlo simulations we recommend 50 and 75 mg/kg/24h amoxicillin in three doses for patients with GA 36-37 and 38-42 weeks, respectively. Study HighlightsWHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? þ To date, there are no data on the effect of moderate hypothermia on the pharmacokinetics (PK) of amoxicillin in term neonates. Only few studies have been performed to evaluate the PK of this antibiotic in noncooled (pre)term neonates. WHAT QUESTION DID THIS STUDY ADDRESS? þ To our knowledge, this is the first prospective study evaluating and describing the PK of amoxicillin during all phases of controlled hypothermia in newborns, e.g., the hypothermic, rewarming, and normothermic phases.WHAT THIS STUDY ADDS TO OUR KNOWLEDGE þ A description of the PK properties of amoxicillin in term newborns with hypoxic-ischemic encephalopathy (HIE) due to perinatal asphyxia receiving hypothermia treatment. Gestational age (GA), postnatal age (PNA), urine output, and body temperature were significant covariates on amoxicillin clearance (Cl). HOW THIS MIGHT CHANGE CLINICAL PHARMA-COLOGY OR TRANSLATIONAL SCIENCE þ Based on the newly developed PK-model, we advise an amoxicillin dosing regimen of 50 or 75 mg/kg/24h in three doses for patients with GA 36 or GA 38-42 weeks, respectively.Term neonates who experience a severe hypoxic-ischemic insult during birth and develop encephalopathy are treated with hypothermia.1,2 This improves long-term outcomes and reduces mortality rates.2-9 These patients may suffer from early-onset sepsis with Streptococcus agalactiae (incidence rate 0.43% (95% confidence interval (CI) 0.37-0.49)), while Listeria monocytogenes should also be considered.10 Because asphyxia due to infection is difficult to distinguish from asphyxia without infection, antibiotics, such as amoxicillin, are frequently used.11 For efficacy, as a surrogate marker, the time that the nonprotein-bound concentration in blood exceeds the minimum inhibitory concentration (T>MIC) should be at least 40-50% in these patients.12 Although b-lactam antibiotics such as amoxicillin are considered safe due to the wide therapeutic range, excessive accumulation can lead to the development of adverse drug events, such as seizures and crystalluria. 13Despi...

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Section: Pharmacokinetic Model Buildingmentioning

confidence: 99%

Section: Structural Modelmentioning

confidence: 99%

Population Pharmacokinetics of Amoxicillin in Term Neonates Undergoing Moderate Hypothermia

Bijleveld

Mathôt

Lee

et al. 2017

Clin Pharma and Therapeutics

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“…Weight was incorporated into disposition parameters using theorybased allometric relationships [12] standardized to 70 kg [13] as shown below: POPCL and POPV are the population standard values. CL stands for clearance and V for central volume of distribution in subjects with the same weight.…”

Section: Methodsmentioning

confidence: 99%

Mechanistic Model for Blood Pressure and Heart Rate Changes Produced by Telmisartan in Human Beings

Chae

Son

Kim

et al. 2017

Basic Clin Pharma Tox

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Telmisartan, an angiotensin receptor blocker (ARB), is indicated for the treatment of essential hypertension. This study aimed to develop a mechanistic model of telmisartan drug effect in human beings using non-invasive markers. Data were acquired from a previous study where telmisartan 80 mg was given once daily for 6 days. Systolic (SBP) and diastolic blood pressure (DBP) and heart rate (HR) were measured before dosing for days 1-5 and serially after the last dose. Mean arterial pressure (MAP) and pulse pressure (PP) were calculated from SBP and DBP. Relationships between MAP, PP, HR and total peripheral resistance (TPR) were developed. Circadian variation was incorporated into PP and HR, and TPR was assumed to adjust itself in response to changes in PP and HR based on baroreflex mechanism. Drug effects were then described as lowering the set point of MAP through TPR with a physiological feedback effect stimulating HR and PP. Drug concentrations were described by a two-compartment disposition model with first-order absorption and lag time, and first-order elimination. Circadian variation was described by cosine functions, having periods of 12 and 24 hr. A log-linear model was used to describe drug effect, with estimated drug effect parameter of 0.051/hr. Estimated fractional turnover rate of PP, HR and TPR was 11.2 hr. The model successfully described the time courses of these cardiovascular variables. This work demonstrated the feasibility of using non-invasive cardiovascular measurements to derive a mechanistic model for telmisartan in human beings. The model may be suitable for other ARBs.Telmisartan is an antagonist of the angiotensin II type 1 (AT1) receptor that is used for the treatment of hypertension. It selectively inhibits stimulation of the AT1 receptor by angiotensin II. It has a high volume of distribution and is eliminated mainly by the kidneys which results in a long terminal elimination half-life. The compound is not metabolized by cytochrome P450 isoenzymes and has a low risk for P450-based drug interactions [1,2].The action of telmisartan is known to lead to inhibition of aldosterone secretion and reduced vasoconstriction. The time course of its effect involves both rapid and slow responses. The rapid response is mainly due to antagonizing angiotensin II vasoconstriction. The slow response is due to antagonizing angiotensin-mediated aldosterone secretion which leads to a natriuretic effect, followed by decreased plasma volume and consequent decrease in cardiac stroke volume. Both the rapid and slow effects contribute to lowering of blood pressure [1].A population pharmacokinetic (PK) model for telmisartan was first published in 2003 [3] and reported that a two-compartment disposition model with first-order absorption and elimination described the data. A PKPD model of telmisartan has been published [4] in spontaneously hypertensive rats. To the authors' knowledge, no PKPD model of telmisartan has been published in human beings. Previous PKPD models used either an empirical modelli...

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“…Moreover, several studies have proved that this theory-based scaling approach is fairly reliable. [4] As a result, allometric scaling is adopted without the process of covariate selection. However, useful allometric scaling relationship is not always available.…”

Section: Introductionmentioning

confidence: 99%

Relationship between body weight and postmenstrual age in a Korean pediatric population

Guk

Chae

Park

2017

Transl Clin Pharmacol

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Weight is a covariate representative of body size and is known to influence drug disposition. Recently, with increased use of allometric scaling, this variable has become more significant in accounting for variability in pharmacokinetic parameters. In adults, weight can be considered as a time invariant covariate because physical development is complete. As a result, when weight is missing in data, the typical or median value (say, 70 kg) could be imputed. On the contrary, weight continuously changes with age in the pediatric population. In this case, it is more appropriate to consider different median weight for each age group. We constructed a prediction model for weight using postmenstrual age (PMA) with the data consisting of 83,014 Korean pediatric patients. Weight, PMA, and gender information were collected from electronic medical records. Sigmoid models multiplied by exponential or logistic function were tested for basic model structure. Covariate effects on model parameters were then investigated using selection criteria of p < 0.001. All analyses were performed using NONMEM 7.3.0 and R3.2.0. The sigmoid model multiplied by logistic function best described the data and there was a significant difference between boys and girls in model parameters. It is expected that the results obtained in this work can be used for imputation of missing weights in pediatrics when PMA is available. In addition, the developed model can be used for clinical studies in children under 12 years old whose weight change rapidly with age and for model building in dealing with time varying body weight as a covariate.

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A Pharmacokinetic Standard for Babies and Adults

Cited by 310 publications

References 133 publications

Population Pharmacokinetics of Amoxicillin in Term Neonates Undergoing Moderate Hypothermia

Population Pharmacokinetics of Amoxicillin in Term Neonates Undergoing Moderate Hypothermia

Mechanistic Model for Blood Pressure and Heart Rate Changes Produced by Telmisartan in Human Beings

Relationship between body weight and postmenstrual age in a Korean pediatric population

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