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    Clinton F. Stewart, PharmD

    Clinton F. Stewart, PharmD

    Fewer blood samples needed to check drug level

    A team of researchers at St. Jude has figured out how to minimize the number of times children receiving the cancer drug topotecan must have blood samples drawn when performing pharmacokinetic (PK) studies, while ensuring accurate results. PK studies allow clinicians to monitor the amount of drug in patients’ bloodstreams to maintain levels high enough to kill cancer cells and low enough to minimize toxicity.

    The St. Jude team, led by Clinton Stewart, PharmD, Pharmaceutical Sciences, developed a specific “limited sampling model” (LSM) for administering topotecan either intravenously or orally. Stewart is senior author of a paper that appears in the online edition of Cancer Chemotherapy and Pharmacology; Kellie Turner, PharmD, a graduate student, is first author.

    LSMs tell clinicians how long they must wait after administering topotecan to take each of three blood samples to check drug levels. The specific times noted by the guidelines provide accurate information on drug levels based on fewer samples, Stewart says. Using results based on the PK studies, clinicians will be able to decide whether the dose must be increased, decreased or kept unchanged while minimizing the time, cost and inconvenience of blood sampling for the child.

    Other authors of the study include Lisa C. Iacono, PharmD, formerly of St. Jude; John Panetta, PhD, Pharmaceutical Sciences; and Victor Santana, MD, Najat Daw, MD, and Amar Gajjar, MD, all of Hematology-Oncology.

    Last update: September 2005