To date, a direct correlation between DPYD gene mutation and decreased 5-FU clearance has only been suggested but never been proven. In this study, we provide the first detailed analysis of 5-FU pharmacokinetics in a patient with low DPD-activity due to selleck products heterozygosity for a mutant allele of the gene encoding DPD. Figure 1 Metabolism of 5-FU. 5-Fluoro-2��-deoxyuridine-5��-monophosphate (FdUMP) is the cytotoxic product resulting from a multi-step 5-FU activation route. FdUMP inhibits the enzyme thymidylate synthase (TS), which leads to intracellular accumulation … METHODS Chemicals 5-Fluorouracil was obtained from Sigma Chemical Co. (Zwijndrecht, The Netherlands). 5,6-Dihydro-5-fluorouracil was kindly provided by Roche Laboratories (Basel, Switzerland).

AmpliTaq Taq polymerase and BigDye-Terminator-Cycle-Sequencing-Ready-Reaction kit were supplied by Perkin Elmer (San Jose, CA, USA). A Quaquik Gel Extraction kit was obtained from Qiagen (Hilden, Germany). Human heparinised plasma was obtained from the Red Cross Blood Bank (Groningen, The Netherlands). [4-14C]Thymine (1.85�C2.22GBqmmol?1) was obtained from Moravek Biochemicals (CA, USA) and Lymphoprep (spec.gravity 1.077gml?1, 280mOsm) was from Nycomed Pharma AS (Oslo, Norway). Leucosep tubes were supplied by Greiner (Frickenhausen, Germany). All other chemicals were of analytical grade. Patient and controls All patients were treated for Dukes C colorectal cancer and participated in a protocol that had been designed to study 5-FU and DHFU pharmacokinetics.

The protocol was approved by the Medical Ethics Review Committee of the Martini Hospital Groningen and written informed consent was obtained from all patients. All patients who entered this protocol were chemotherapy naive. Chemotherapy consisted of leucovorin 20mgm?2 combined with 5-FU 425mgm?2, both on 5 successive days, in a 28-day cycle. Blood sampling was carried out on the first day of the first chemotherapy cycle immediately following the 5-FU dose, administered as bolus intravenous injection over 2min. Leucovorin was infused after the end of blood sampling. On the following 4 days, the same 5-FU dose was administered as short time infusion, after leucovorin administration. One patient experienced severe toxicity during the first chemotherapy cycle and, therefore, a screening on DPD deficiency was initiated.

Data from six patients who participated in the same study protocol and who showed no signs of severe toxicity were randomly selected for reference pharmacokinetics, DPYD genotyping and DPD enzyme activity. These patients served as controls. Collection of blood samples For Anacetrapib pharmacokinetic sampling, a canule was placed in the arm of the patient contralateral from drug administration. Blood samples (5ml) were collected in heparinised tubes just before, and 2, 5, 10, 20, 30, 45, 60, 80, 100, 120, 150 and 180min postinjection.