Pharmacokinetics in rabbits and anti-sphingomyelinase D neutralizing power of Fab, F(ab’)(2), IgG and IgG(T) fragments from hyper immune equine plasma.

This study is about the extraction and analysis of different types of immunoglobulins and its fragments from the plasma of hyper immunized horses, their pharmacokinetic properties in rabbits and their neutralizing ability against sphingomyelinase D, an enzyme which forms part of the venom of Loxosceles spiders.

Process of Immunoglobulin Separation

• The study focused on the sequential processing and separation of different types of immunoglobulins from horse plasma. Specifically, these were whole IgG, IgG(T)-less IgG (referred to in this study as IgG) and IgG(T).
• The researchers also manufactured Fab and F(ab’)(2) fragments from these antibodies. Fab and F(ab’)(2) are smaller antibody pieces obtained by cleaving the full antibody molecule.

Pharmacokinetics in Rabbits

• Pharmacokinetics is the study of how a drug is absorbed, distributed, metabolized and eliminated by the body over time. Here, researchers studied the pharmacokinetics of the mentioned immunoglobulin types and fragments in rabbits.
• The Fab and F(ab’)(2) fragments demonstrated a tri-exponential pharmacokinetic model well, which is a pattern of absorption and elimination over time that can be described mathematically as the sum of three exponential functions.
• However, the pharmacokinetics of the IgG and IgG(T) immunoglobulins departed from the tri-exponential model 120 hours after the rabbits were injected with these immunotherapeutics, due to the rabbits producing anti-horse antibodies. This resulted in a surge of these anti-horse antibodies after about 120 hours, peaking at approximately 260 hours and slowly decreasing afterwards.

Anti-Sphingomyelinase D Neutralizing Power

• The horses from which the plasma was sourced were hyper immunized against sphingomyelinase D. This enzyme is present in the venom of the Loxosceles spider species, suggesting the primary use of these antibodies and fragments would be as an antivenom for Loxosceles spider bites.
• The researchers also studied the sphingomyelinase D neutralizing power of these immunoglobulins and their fragments. However, the abstract doesn’t provide in-depth findings on these results.