Related Experiment Video
Updated: Nov 29, 2025
07:59
Fat-Water Phantoms for Magnetic Resonance Imaging Validation: A Flexible and Scalable Protocol
Published on: September 7, 2018
11.8K
Normal fat mass cannot be reliably estimated in typical pharmacokinetic studies.
Roeland E Wasmann1, Elin M Svensson2,3, Stein J Schalkwijk2
1Department of Pharmacy, Radboud Institute for Health Sciences, Radboud University Medical Center, Geert Grooteplein-Zuid 10, 6500 HB, Nijmegen, The Netherlands. Roeland.wasmann@uct.ac.za.
European Journal of Clinical Pharmacology
|November 18, 2020
Summary
Estimating normal fat mass (NFM) in pharmacokinetic studies shows low precision. Careful study design is crucial before using NFM to avoid incorrect conclusions about body size and drug behavior.
Area of Science:
- Pharmacokinetics
- Body Composition Analysis
- Biostatistics
Background:
- Body size is a key factor influencing pharmacokinetics.
- Estimating normal fat mass (NFM) is increasingly used to explain pharmacokinetic variability.
- The reliability of NFM estimation in typical study settings remains uncertain.
Purpose of the Study:
- To evaluate the reliability of normal fat mass (NFM) estimation in pharmacokinetic studies.
- To assess the impact of fraction fat (Ffat) on NFM estimation precision.
- To determine if NFM can be reliably estimated in typical study sizes.
Main Methods:
- A pharmacokinetic simulation study was conducted.
- The reliability of NFM estimation was evaluated in a sample size of 30.
- Various fraction fat (Ffat) values were investigated.
Main Results:
- NFM parameter estimates exhibited high imprecision across multiple scenarios in typical pharmacokinetic studies.
- A scenario with true Ffat of 0.5 for clearance showed a wide 95% confidence interval (-0.1 to 2.1).
- This imprecision can lead to misinterpretations of body size relationships in pharmacokinetics and incorrect extrapolation.
Conclusions:
- Normal fat mass (NFM) estimation should be used cautiously in pharmacokinetic studies due to low precision of fraction fat (Ffat) estimates.
- Thorough study design evaluation, including sample size assessment, is essential before implementing NFM estimation.
- Ensuring sufficient study design is critical for the valid application of NFM in pharmacokinetics.
Related Concept Videos
01:21Drug Dosing: Obese Patients
99
In the United States, obesity is a prominent concern. It is linked to heightened mortality rates due to increased occurrences of conditions such as hypertension, atherosclerosis, coronary artery disease, and diabetes compared to nonobese individuals. A patient is classified as obese if their actual body weight surpasses the ideal or desirable body weight by 20%, based on Metropolitan Life Insurance Company data. Ideal body weights consider average weights and heights for males and females...
99
01:25Pharmacokinetics in Obese Patients: Drug Absorption and Distribution
121
Obesity significantly alters the pharmacokinetic processes of drug absorption and distribution, presenting unique challenges in medical treatment. The increased fat tissue and decreased lean muscle in obese individuals can significantly affect how drugs are absorbed into the body and distributed across different tissues. This alteration can lead to variances in the effectiveness and safety of medications, necessitating adjustments in dosing or drug selection for obese patients.One notable...
121
01:01Dosage Regimens: Partial Pharmacokinetic Parameters
67
It is not uncommon for complete drug pharmacokinetic profiles to remain elusive in pharmacokinetics. This necessitates certain educated assumptions by pharmacokineticists to determine appropriate dosage regimens without comprehensive pharmacokinetic data from animal or human studies. One prevalent assumption is setting the bioavailability factor, denoted as F, to 1 or 100%. This assumption caters to the scenario where a drug doesn't achieve full systemic absorption, resulting in the patient...
67
01:26Pharmacokinetic Models: Comparison and Selection Criterion
234
Physiological and compartmental models are valuable tools used in studying biological systems. These models rely on differential equations to maintain mass balance within the system, ensuring an accurate representation of the dynamic processes at play.
Physiological models take a detailed approach by considering specific molecular processes. They can predict drug distribution, metabolism, and elimination changes, providing a comprehensive understanding of how drugs interact with the body.
Physiological models take a detailed approach by considering specific molecular processes. They can predict drug distribution, metabolism, and elimination changes, providing a comprehensive understanding of how drugs interact with the body.
234
01:13Physiological Pharmacokinetic Models: Assumption with Protein Binding
143
Physiological models with protein binding in pharmacokinetics offer a sophisticated approach to understanding drug disposition. These models consider drug-protein interactions, enabling them to effectively predict drug concentrations in different organs and tissues. This precision aids in accurate drug dosing, providing a significant advantage over conventional models. A key process within these models is equilibration, which ensures that drug concentrations achieve a steady state within the...
143
01:20Pharmacokinetics in Obese Patients: Drug Metabolism and Excretion
86
Drug metabolism, a critical process in the liver, involves two primary phases: Phase I reactions and Phase II conjugation. Obesity introduces significant alterations in this metabolic process, primarily due to fatty infiltration of the liver, leading to conditions such as nonalcoholic fatty liver disease (NAFLD). This condition can modify the activities of both Phase I and II enzymes, impacting how drugs are metabolized in obese patients.Phase I metabolism sees variable effects across...
86