PHARMACOKINETICS OF PROTEIN THERAPEUTICS
The in vivo disposition of peptide and protein drugs may often be predicted to a large degree from their physiological function (Tang and Meibohm, 2006). Peptides, for example, which frequently have hormone activity, usually have short elimination half-lives, which is desirable for a close regulation of their endogenous levels and thus function. Insulin, for example shows dose-dependent elimination with a relatively short half-life of 26 and 52 minutes at 0.1 and 0.2 U/kg, respectively. Contrary to that, proteins that have transport tasks such as albumin or long-term
immunity functions such as immunoglobulins have elimination half-lives of several days, which enables and ensures the continuous maintenance of physio-logically necessary concentrations in the bloodstream (Meibohm and Derendorf, 1994). This is for example reflected by the elimination half-life of antibody drugs such as the anti-epidermal growth factor receptor antibody cetuximab, an IgG1 chimeric antibody forwhich a half-life of approximately 7 days has been reported (Herbst and Langer, 2002).