Postnatal Hepatobiliary and Gastrointestinal Systems Development and Impact on ADME

Wendy G Halpern1, April Kluever2, Armando R Irizarry Rovira3

  • 17412Genentech, South San Francisco, CA, USA.

Toxicologic Pathology
|October 5, 2021
PubMed

Insights

Postnatal development impacts organ sensitivity to toxicity, affecting drug disposition and safety assessments. Understanding these developmental changes in systems like the gastrointestinal tract and liver is crucial for accurate risk evaluation.

Area of Science:

  • Developmental toxicology
  • Pharmacokinetics and drug metabolism
  • Neonatal and juvenile physiology

Background:

  • Postnatal development influences target organ sensitivity and toxicological exposure.
  • Neonatal gastrointestinal tract (GIT) maturation is critical for nutrient absorption and drug disposition.
  • Hepatic maturation in juvenile rodents involves changes in drug-metabolizing enzymes and transporters.

Purpose of the Study:

  • To highlight the impact of postnatal development on toxicity.
  • To emphasize the importance of understanding developmental changes in drug disposition.
  • To inform the interpretation of developmental toxicity studies.

Main Methods:

  • Review of physiological changes in neonatal and juvenile GIT and liver.
  • Analysis of how these changes affect drug pharmacokinetics and toxicity.
  • Discussion of the role of animal models in developmental toxicity assessment.

Main Results:

  • Gastrointestinal tract and hepatic functions mature postnatally, influencing drug disposition.
  • Maturation involves changes in motility, enzyme/transporter function, permeability, and microbiome.
  • These developmental changes can affect rodent pharmacokinetics and toxicity profiles.

Conclusions:

  • Interpreting developmental toxicity requires knowledge of developing human and nonclinical systems.
  • Pilot studies in juvenile rodents can help mitigate toxicity related to drug disposition.
  • Accurate pediatric dose estimation necessitates understanding developmental pharmacokinetics.

Related Concept Videos

Pharmacokinetics in Pediatric Patients: Overview and Drug Absorption01:23

Pharmacokinetics in Pediatric Patients: Overview and Drug Absorption

Understanding the physiological differences in the pediatric population is crucial for effective pharmacotherapy. Neonates, infants, and children exhibit significant variations in gastric pH, gastric emptying time, intestinal transit time, and biliary function. These variations profoundly affect oral drug absorption, necessitating a nuanced approach to pediatric dosing.Neonates present with a unique physiological profile, having a gastric pH greater than 4 and faster and more irregular gastric...
31
Pharmacokinetics in Pediatric Patients: Drug Metabolism01:24

Pharmacokinetics in Pediatric Patients: Drug Metabolism

In pediatric care, understanding the nuances of hepatic drug metabolism is crucial, as it significantly differs from that of adults. This divergence is primarily due to the developmental stage of drug-metabolizing enzymes, which affects how medications are processed in the body. In neonates, for instance, the activity of Phase I enzymes—critical for the initial breakdown of drugs—is markedly reduced, functioning at just 20–40% of the levels seen in adults. This reduction poses...
34
Effect of Hepatic Disease on Pharmacokinetics: Pathophysiologic Assessment and Liver Function Test01:22

Effect of Hepatic Disease on Pharmacokinetics: Pathophysiologic Assessment and Liver Function Test

In clinical practice, the direct measurement of hepatic blood flow to evaluate liver function presents significant challenges due to the intricate and specialized nature of the necessary techniques. Consequently, healthcare professionals often rely on empirical estimates derived from thorough patient examinations and liver function tests to gauge liver health. Among the tools at their disposal, the Child–Pugh and MELD scoring systems stand out for their ability to categorize and assess...
26
Anatomy of the Intestines01:23

Anatomy of the Intestines

Although digestion of proteins, carbohydrates, and lipids may begin in the stomach, it is completed in the intestine. The absorption of nutrients, water, and electrolytes from food and drink also occurs in the intestine. The intestines can be divided into two structurally distinct organs—the small and large intestines.
Small Intestines
The small intestine is an ~7 meter-long tube with an inner diameter of just 2.5 cm. Since most nutrients are absorbed here, the inner lining of the...
84.2K
Hepatic Drug Excretion: Enterohepatic Cycling01:17

Hepatic Drug Excretion: Enterohepatic Cycling

Enterohepatic cycling involves the active secretion of drugs and their metabolites into the bile via transporters in the canalicular membrane of hepatocytes. This secretion is an integral part of the digestive process, releasing these substances into the gastrointestinal (GI) tract.
Post-release drugs and metabolites can be reabsorbed into the body from the intestine. For conjugated metabolites like glucuronides, reabsorption requires enzymatic hydrolysis by intestinal microflora. This...
1.9K
Factors Affecting Drug Response: Overview01:21

Factors Affecting Drug Response: Overview

When it comes to infants and young children, they are typically administered smaller doses of medication in comparison to adults. This is primarily because their organ functions still need to fully develop, meaning their bodies are not as efficient at metabolizing or eliminating drugs. Additionally, their blood-brain barrier is more permeable than in adults. As a result, high concentrations of drugs can easily penetrate the central nervous system (CNS), potentially leading to neurological...
2.5K