Temporal and Pharmacokinetic Aspects in Delivery of Peptides and Proteins

Abstract

The rational administration of any drug to a patient requires some knowledge of the anticipated efficacy and toxicity for a particular dose of that drug. When an understanding of how an individual patient will absorb and eliminate a drug is coupled together with knowledge of the pharmacologic effects of a given amount of the drug, a particular dose can be selected that will result in clinical efficacy and minimal toxicity. Such considerations have been defined adequately for many classical drugs; however, this approach has not been used as yet for the new peptide and protein therapeutic agents. Thus, today we are interested in gaining an understanding of the pharmacokinetics and pharmacodynamics of peptide and protein drugs. Pharmacokinetics may be simply described as the mathematical relationship that exists between the dose of a drug and the measureable concentration in a readily accessible site in the body (e.g., plasma or blood). Pharmacodynamics extends this relationship to a correlation between measured concentrations of drug and the pharmacologic effect. As a simple description, pharmacokinetics describes what the body does to the drug, as opposed to pharmacodynamics which describes what the drug does to the body. There are two major uses for pharmacokinetics. First, as a tool in therapeutics to help the clinician choose the right dosage regimen for a particular drug in a specific patient. Second, pharmacokinetics may be used as a tool in defining drug disposition. As indicated above, up to the present time the therapeutic use of pharmacokinetics for proteins and peptide drug compounds has not been realized. However, regulatory agencies do require information concerning drug disposition which can be best described using pharmacokinetic principles, i.e., the use of pharmacokinetics as a tool in defining drug disposition.