Plasma protein binding
The binding of a peptide to proteins in the blood (primarily albumin). Only the unbound (free) fraction is pharmacologically active. High protein binding extends half-life but reduces the free active concentration.
Frequently Asked Questions
What is Plasma protein binding?
Why is Plasma protein binding important in peptide research?
Related Terms
The time required for the concentration of a peptide in the body to decrease by half. Determines dosing frequency — short half-life peptides (minutes) need daily dosing, while long half-life peptides (days) can be dosed weekly.
Volume of distributionA pharmacokinetic parameter relating the total amount of drug in the body to the plasma concentration. A large Vd indicates extensive tissue distribution; a small Vd suggests the peptide stays primarily in the bloodstream.
BioavailabilityThe fraction of an administered dose that reaches systemic circulation unchanged. Subcutaneous injection provides 65–95% bioavailability for most peptides; oral bioavailability is typically below 1% without absorption enhancers.