Thesis (Ph.D. (Pharmacy)) - Rhodes University, 2008.

vii ABSTRACT David Čechlovský‡ , Stefanie Kraff*, Ulrich Jaehde* *Institute of Pharmacy, Clinical Pharmacy, University of Bonn, Germany ‡ Department of social and clinical pharmacy, Faculty of pharmacy in Hradec Králové, Charles University in Prague Title of diploma thesis: Individualized pharmacokinetically guided dosage adjustment of fluorouracil (5-FU) using population pharmacokinetic modelling. Objectives: To develop a method to increase the efficacy and tolerability of fluorouracil (5-FU) with pharmacokinetically-guided dose adjustment based on a target AUC. Methods: Blood samples were collected from 90 patients with the diagnosis of colorectal carcinoma treated with fluorouracil (5-FU) administered at various infusion durations. Several versions of compartmental pharmacokinetic models were fitted to the plasma concentration data, using nonlinear mixed effect modelling (NONMEM). Different error models were evaluated. The potential effect of patient covariates was evaluated using a stepwise method. Model evaluation was performed by using the bootstrap method. Results: The one-compartment linear model was chosen as a base model as it was successful in fitting to the data collected..The final model contained Additive Residual Error. A covariate BSA>CL and IIV on CL were significantly correlated to the...

Regensburg, Univ., Diss., 2009.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xxi, 220 p.; also includes graphics Includes bibliographical references (p. 121-127). Available online via OhioLINK's ETD Center

Proefschrift Rijksuniversiteit Groningen. / Met lit.opg. - Met samenvatting in het Engels.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Introduction: Intestinal mucositis is a common side effect of anticancer regimens for first-line treatment of colorectal cancer. Among such drugs are irinotecan and 5-FU used in combination. Many studies have been conducted on the pathogenesis of MI. However, further investigations are necessary, because the course of MI may vary according to the drug regimen and employees. Then aimed to develop a new experimental model of MI induced by the combination of IRI and 5-FU in mice. Methods and Results: C57BL/6 mice (20-25g, n=6) were injected with saline (100ÂL, i.p), IRI (30 or 45 mg/kg, i.p), 5-FU (25, 37.5 or 50 mg/kg, i.p) or IRI+5-FU for 4 days. On day 7, diarrhea, weight loss, and blood leukocyte count were registered. Following animal euthanasia, ileum samples were collected for histopathological analysis, myeloperoxidase activity (MPO, neutrophil/mg protein), TNF-&#945; and IL-6 levels (pg/mg tissue). Kaplan-Mayer log rank test, Kruskal Wallis/Dunnâs or ANOVA/Bonferroniâs test was used for statistical analysis. p<0.05 was accepted. The best dose combination able to induce IM with no important mortality on day 7 was 5-FU (37.5 mg/kg) +IRI (45 mg/kg) (0% mortality), which was then used for subsequent studies. IRI+5-FU induced (p<0.001) diarrhea (2[0-3]), weight loss (86.7Â3.9g), and leukopenia (7.3 2.3 x103) versus saline group (0[0-1]; 101.1Â0.6; 215.5 54.1, respectively) or each drug given alone (5-FU: diarrhea (0[0-1]), weight loss [92.6Â2.7], and leukopenia [30.4 13.4]; IRI: diarrhea (0[0-1]), weight loss [94.8Â2.1], and leukopenia [49.2 5.5]). In addition, IRI+5-FU induced inflammatory cells infiltration, and loss of villi and crypt architecture (4[3-4]), increased in MPO activity (14641Â1598 neutrophil/mgproteÃn), TNF-a (3.2Â0.9 pg/mg tissue), IL-6 (1.4Â0.5 pg/mg tissue) tissue levels versus saline-injected group (0[0-1], 5747Â1155; 0.7Â0.2; 0.3Â0.1) or the drugs injected alone (5-FU: Intestinal damage (2.5[2-3]), MPO [3788Â1212], TNF-&#945; [0.7Â0.2], IL-6 [0.2Â2.3]; IRI: Intestinal damage (1[0-2]), MPO [3580Â1613], TNF-&#945; [0.4Â0,2], IL-6 [0.07Â0.05]) (p<0.05). Conclusion: We developed a new experimental model of IM induced by the combination of IRI+5-FU in mice, which opens perspective for a more appropriate knowledge concerning the pathogenesis of IM. / IntroduÃÃo: Mucosite intestinal à um efeito adverso comum dos regimes anticÃncer de primeira linha para o tratamento do cÃncer colorretal. Dentre esses fÃrmacos estÃo o irinotecano e 5-FU utilizados em associaÃÃo. Muitos estudos tÃm sido realizados sobre a patogÃnese da MI. No entanto, novas investigaÃÃes sÃo necessarias, pois o curso da MI pode variar de acordo com o fÃrmaco e regime empregados. Objetivou-se entÃo desenvolver um novo modelo experimental de MI induzida pela combinaÃÃo de IRI e 5-FU em camundogos. MÃtodos e Resultados: camundongos C57BL/6 (20-25g, n=6) foram injetados com salina (100ÂL, i.p), IRI (30 ou 45 mg/kg, i.p), 5-FU (25, 37,5 ou 50 mg/kg, i.p) ou IRI+5-FU em doses combinadas por 4 dias. No 7 dia, diarreia, perda de peso e contagem de leucÃcitos foram registradas. ApÃs a eutanÃsia dos animais, amostras do Ãleo foram coletadas para anÃlise histopatolÃgica, atividade de mieloperoxidase (neutrÃfilo/mg proteÃna), nÃveis de TNF-&#945; e IL-6 (pg/mg tecido). Teste Kaplan-Mayer log rank, Kruskal Wallis/Dunnâs ou teste ANOVA/Bonferroni foram usados para analise estatistica. p<0,05 foi aceito como significativo. A melhor combinaÃÃo de dose para induzir a MI sem mortalidade importante no 7 dia foi 5-FU (37,5 mg/kg) + IRI (45 mg/kg) (0% mortalidade), que foi entÃo usada para estudos subsequentes. IRI+5-FU induziu (p<0,001) diarreia (2[0-3]), perda de peso (86,7Â3,9g), e leucopenia (7,3 2,3x103) versus grupo salina (0[0-1]; 101,1Â0,6; 215,5 54,1, respectivamente) ou cada droga dada sozinha (5-FU: diarreia (0[0-1]), perda de peso [92,6Â2,7], e leucopenia [30,4 13,4]; IRI: diarreia (0[0-1]), perda de peso [94,8Â2,1], e leucopenia [49,2 5,5]). Adicionalmente, IRI+5-FU induziu infiltrado de cÃlulas inflamatÃrias, perda de vilos e arquitetura das criptas (4[4-4]), aumento na atividade de MPO (14641Â1598 neutrÃfilo/mgproteÃna), TNF-a (3,2Â0,9 pg/mg de tecido), IL-6 (1,4Â0,5 pg/mg de tecido) nÃveis teciduais versus grupo injetado com salina (0[0-1], 5747Â1155; 0,7Â0,2; 0,3Â0,1) ou com fÃrmacos injetados isoladamente (5-FU: dano intestinal (2.5[2-3]), MPO [3788Â1212], TNF-&#945; [0,7Â0,2], IL-6 [0,2Â2,3]; IRI: dano intestinal (1[0-2]), MPO [3580Â1613], TNF-&#945; [0,4Â0,2], IL-6 [0,07Â0,05]) (p<0,05). ConclusÃo: Desenvolvemos um novo modelo experimental de MI induzida pela combinaÃÃo de IRI+5-FU em camundongos, que abre perspectiva para um maior conhecimento sobre a patogÃnese da MI.

No description available.

Folate blood levels in North America have dramatically increased over the past decade owing to folic acid (FA) fortification and widespread supplement use. Furthermore, over 50% of newly diagnosed colorectal cancer (CRC) patients use vitamin supplements containing FA while receiving chemotherapy whose mechanisms of action are based on interruption of folate metabolism. This study therefore investigated whether FA supplementation can affect chemosensitivity of human colon cancer cells to 5FU, the cornerstone of CRC treatment, using a xenograft model. FA supplementation was associated with a non-dose dependent decrease in chemosensitivity, where mice receiving 8 mg FA did not respond to 5FU and had greater tumor growth with treatment, compared to 2 (control) or 25 mg FA. Results of this study pose concern given the drastically increased intake of FA, particularly among recently diagnosed CRC patients, and from mandatory fortification. Further studies are warranted to confirm our findings and to elucidate underlying mechanisms.

Folate is an essential cofactor in one-carbon transfer reactions including nucleotide biosynthesis, thereby playing an important role in DNA replication and repair. In cancer cells, folate depletion interrupts DNA synthesis, thereby causing cancer cell death. This has been the basis for chemotherapy using antifolates and 5-fluorouracil (5FU). We determined the effect of folate deficiency on the sensitivity of colon cancer cells to 5FU in a well established in vitro model of folate deficiency. Folate deficient cells had lower intracellular folate concentrations, had functional evidence of intracellular folate depletion, proliferated less, and had increased chemosensitivity to 5FU with and without Leucovorin. These data suggest that folate deficiency significantly enhances the sensitivity of colon cancer cells to 5FU based chemotherapy via changes in intracellular folate. Dietary or other strategies to deplete intracellular folate concentrations in colon cancer cells to enhance chemosensitivity to 5FU are worthy of further investigation.

Folate blood levels in North America have dramatically increased over the past decade owing to folic acid (FA) fortification and widespread supplement use. Furthermore, over 50% of newly diagnosed colorectal cancer (CRC) patients use vitamin supplements containing FA while receiving chemotherapy whose mechanisms of action are based on interruption of folate metabolism. This study therefore investigated whether FA supplementation can affect chemosensitivity of human colon cancer cells to 5FU, the cornerstone of CRC treatment, using a xenograft model. FA supplementation was associated with a non-dose dependent decrease in chemosensitivity, where mice receiving 8 mg FA did not respond to 5FU and had greater tumor growth with treatment, compared to 2 (control) or 25 mg FA. Results of this study pose concern given the drastically increased intake of FA, particularly among recently diagnosed CRC patients, and from mandatory fortification. Further studies are warranted to confirm our findings and to elucidate underlying mechanisms.