Analysis of the effects of obesity on the pharmacokinetics (PK) of adalimumab in children with Juvenile Idiopathic Arthritis (JIA)

Juvenile idiopathic arthritis (JIA) is a chronic (long-term) condition that causes joint pain, swelling, and stiffness in children. It is the most common type of arthritis in children, affecting about 1 in 1,000 young people worldwide.

Adalimumab is a biologic treatment (a medicine made from living cells) that helps reduce inflammation (swelling and immune system activity) and is commonly used to treat JIA. However, it is not yet fully understood how obesity (which means they weigh more than is considered healthy for their age and sex) may affect the way children’s bodies handle this medication — that is, how it is absorbed, distributed, and removed from the body. These processes together are called pharmacokinetics (PK).

This project will use data that have already been collected from a completed clinical trial of children aged 4–17 years with JIA. The goal is to build a “population pharmacokinetic model” — a type of analysis that helps us understand how different factors, such as age, sex, and body size, affect how a drug moves through the body. The study will examine several ways of measuring body size, such as total body weight, lean body mass (the weight of the body excluding fat), and body mass index (BMI, a measure based on weight and height). We will compare these factors between children who have obesity and those who do not.

We expect to find that children with obesity will clear adalimumab from their bodies faster than children without obesity. This is based on observations of higher medication clearance in both children and adults treated with biologic medications as reported in our published papers (PubMed ID: 34790070 and 41310951). This could mean that higher doses may be needed to achieve the same levels of the medicine in the body. Understanding these differences will help doctors make better dosing decisions in the future, ensuring that all children with JIA — regardless of body size — receive the safest and most effective treatment possible.