Pharmacokinetics: Unique challenges in blood monitoring for oncology nurses

BACKGROUND: Pharmacokinetics (PK) is the study of the absorption, distribution, metabolism, and excretion of drugs. Many chemotherapeutic agents have a sensitive PK index, in which a small margin in blood concentrations is the difference between nontherapeutic, therapeutic, and adverse outcomes. OBJECTIVES: This article will provide an overview of evidence-based approaches to the collection of PK samples, monitoring of PK levels, and the resulting management of patients undergoing PK testing. METHODS: A case study involving busulfan, an alkylating agent used in the pre-stem cell transplantation setting, will highlight the cross-contamination of samples while a drug is being infused through a central venous catheter with PK sample collection from a proximal peripherally inserted central catheter. The influence of false elevations in drug concentrations on PK-guided dose adjustments will also be emphasized. FINDINGS: Imprecise blood collections or cross-contamination of samples may lead to inaccurate drug concentration results and, subsequently, undesired low or high drug dosage calculations.