| Autor: |
Ho, Dah H., Covington, Wendy, Brown, Nita, Lin, San N., Pazdur, Richard, Yuang-Yi Huo, Creaven, Patrick J., Rustum, Youcef M., Meropol, Neal J., Lassere, Yvonne, Kuritani, Jun, Hayakawa, Tomohisa |
| Předmět: |
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| Zdroj: |
Cancer Chemotherapy & Pharmacology; Nov2000, Vol. 46 Issue 5, p351-356, 6p |
| Abstrakt: |
Purpose: To assess the pharmacokinetics of Ftorafur (tegafur, FT), 5-fluorouracil (5-FU), and uracil in 31 cancer patients who were enrolled in phase I studies of oral uracil and FT (UFT). The correlation between pharmacokinetic parameters and toxic effects of UFT was evaluated. Methods: Uracil and FT were orally administered in a 4:1 molar ratio at FT doses of 200–400 mg/m2 per day. Patients also received leucovorin at 150 mg/day. Daily doses were divided into three doses and administered at 8-h intervals for 28 consecutive days. Plasma FT concentrations were measured by high-performance liquid chromatography, and plasma 5-FU and uracil concentrations were determined using gas chromatography-mass spectrometry. National Institutes of Health Common Toxicity Criteria were used for assessment of toxicity. Results: The concentrations of FT, 5-FU, and uracil showed wide interpatient variations. Maximum plasma concentrations (Cpmax) of all three compounds were achieved in 0.3 to 4.0 h. At the various study doses, the terminal half-life (t1/2β) of FT ranged from 3.9 to 5.9 h, the area under the concentration-versus-time curve (AUC0–6h) ranged from 16,220 to 52,446 (ng/ml)h, the total clearance (ClT) ranged from 100 to 175 ml/min, and the steady-state volume of distribution (Vdss) ranged from 18.3 to 28.7 l. The 5-FU generated from FT had an apparent distribution half-life (t1/2α) and an apparent elimination half-life (t1/2β) of 0.3–1.3 h and 4.9–7.0 h, respectively. The AUC0–6h of 5-FU ranged from 120 to 325 (ng/ml)h. Uracil had a t1/2α of 0.2–0.5 h and the level quickly returned to the endogenous level. The AUC0–6h for uracil ranged from 605 to 3764 (ng/ml)h, the ClT ranged from 3225 to 7748 ml/min, and the Vdss ranged from 341 to 1354 l. The Cpmax and AUC0–6h of both FT and uracil were significantly correlated with FT doses (P-values of 0.0244 and 0.0112) and with uracil doses (P-values of 0.0346 and 0.0083), respectively. In addition to interpatient variations, intrapatient variations were also observed in six patients who had pharmacology studies done on days 1 and 26 ± 2 at the same study dose. We found that the repeated treatment with UFT caused cumulative increases in the values of Cpmax, Ctrough, and AUC0–6h of FT and 5-FU. The major toxic effects observed were diarrhea and nausea and vomiting. The occurrence of these toxic effects correlated significantly with the Cpmax and AUC0–6h of 5-FU. Conclusions: The pharmacology studies showed that FT and uracil were readily absorbed orally and that FT was rapidly converted to 5-FU. The preliminary findings suggest that determination of plasma levels of 5-FU after oral administration of UFT may help predict subsequent toxic effects. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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