1,721,244 research outputs found
Phamacokinetic Optimisation of Treatment Schedules for Anthracycline and Paclitaxel in Patients with Cancer:
No full textThe integration of paclitaxel into chemotherapy regimens with anthracyclines offers a new opportunity for devising effective therapy for patients with breast cancer. High response rates have been obtained by combining epirubicin or doxorubicin with paclitaxel. The pharmacokinetic analysis of paclitaxel and anthracyclines, as well as the identification of relationships with their pharmacodynamics, represents a rational approach for treatment optimisation. A schedule-dependent interaction between paclitaxel and anthracyclines has been demonstrated in clinical pharmacokinetic studies. In patients given paclitaxel 125 to 200 mg/m2 as 3- to 24-hour infusions in combination with doxorubicin 48 to 60 mg/m2 as a 48-hour infusion or intravenous bolus, the peak plasma drug concentration (Cmax) of doxorubicin increased significantly and drug clearance was reduced in the sequence paclitaxel-->doxorubicin as compared with doxorubicin-->paclitaxel. The schedule paclitaxel-->doxorubicin was more toxic as compared with doxorubicin-->paclitaxel, and an incidence of 18 to 20% of congestive heart failure was observed in patients with breast cancer given doxorubicin 60 mg/m2 followed by paclitaxel 125 to 200 mg/m2. Likewise, patients given epirubicin 90 mg/m2 had a sudden rebound of epirubicinol plasma concentrations shortly after the start of infusion of paclitaxel 200 mg/m2, with a significant increase in the area under the concentration-time curve (AUC) of epirubicinol as compared with epirubicin alone (1.27 +/- 0.2 vs 0.61 +/- 0.1 mumol/L.h). Moreover, the severity of the myelosuppression induced by paclitaxel, as defined by a sigmoid maximum effect (Emax) relationship between the decrease in neutrophil count and the duration of drug plasma concentrations above the threshold value of 0.1 mumol/L, was significantly enhanced by epirubicin. Finally, chemotherapy with paclitaxel and anthracyclines may be improved by designing pharmacologically guided regimens in order to control the extent of pharmacokinetic interaction and reduce the risk of severe toxicity while maintaining the therapeutic efficacy of the combination. Future protocols should explore the activity of a prolonged paclitaxel infusion in association with an anthracycline separated from the taxane by a washout time interval in order to minimise the inhibitory effects exerted by paclitaxel on P-glycoprotein-mediated biliary clearance of anthracyclines, the most likely cause of pharmacokinetic interactio
Periodontal tissue disposition of Azitromycin.
No full textbstract
The tissue penetration of azithromycin, the prototype of a new class of macrolide antibiotics named azalides, was studied in patients undergoing surgery for third-molar removal. Drug concentrations in plasma, saliva, and periodontal tissues were evaluated in 28 patients treated with azithromycin 500 mg/day per os for 3 consecutive days. Samples of blood, saliva, gingiva, and alveolar bone were collected during oral surgery, 12 hours, and 2.5, 4.5, and 6.5 days after the last dosing, and the azithromycin concentration was measured microbiologically by using Micrococcus luteus NCTC 8440 as the reference organism. The highest concentrations of azithromycin were observed 12 hours after the last dose in plasma, saliva, gingiva, and bone (0.33 +/- 0.04 mg/l, 2.14 +/- 0.30 mg/l, 6.47 +/- 0.57 mg/kg, and 1.86 +/- 0.15 mg/kg, respectively) and then declined gradually. However, consistent levels of the drug in saliva and periodontal tissues could be detected up to 6.5 days, indicating that azithromycin was retained in target tissues and fluids for a long time after the end of treatment. Among the samples examined, the highest concentration of azithromycin was found in the gingiva at each time studied. Moreover, the ratios of salivary or periodontal tissue levels versus plasma concentrations remained nearly unmodified from 12 hours up to 6.5 days. Overall, these results indicate a favorable disposition of azithromycin into saliva and periodontal tissues and suggest that this macrolide antibiotic represents a valuable option in the pharmacologic treatment of odontogenic infection
Gemcitabine, epirubicin and paclitaxel: pharmacokinetic and pharmacodynamic interactions in advanced breast cancer.
No full textThe objectives of this study were to investigate the disposition of gemcitabine, epirubicin, paclitaxel, 2',2'-difluorodeoxyuridine and epirubicinol, and characterize the pharmacokinetic and pharmacodynamic profile of treatment in patients with breast cancer. PATIENTS AND METHODS: The drug dispostion in 15 patients who received gemcitabine 1000 mg/m2, epirubicin 90 mg/m2 and paclitaxel 175 mg/m2 (GEP) on day 1 of a 21-day cycle, was compared with that of patients treated with epirubicin 90 mg/m2 and paclitaxel 175 mg/m2 (EP, n = 6) and epirubicin 90 mg/m2 alone (n = 6). Drug and metabolite levels in plasma and urine were assessed by high-performance liquid chromatography and parameters of drug exposure were related to hematological toxicity by a sigmoid-maximum effect (Emax) model. RESULTS: Paclitaxel administration significantly increased the epirubicinol area under the concentration-time curve, from 357+/-146 (epirubicin) to 603+/-107 (EP) and 640+/-81 h x ng/ml (GEP), and reduced the renal clearance of epirubicin and epirubicinol by 38 and 52.2% and 34.5 and 53% in GEP- and EP-treated patients, respectively, compared with epirubicin alone. Gemcitabine had no apparent effect on paclitaxel and epirubicin pharmacokinetics, and renal clearance of epirubicin and epirubicinol. The only pharmacokinetic/pharmacodynamic relationship observed was between neutropenia and the time spent above the threshold plasma level of 0.1 micromol/l (tC0.1) of paclitaxel, with the time required to obtain a 50% decrease in neutrophil count (Et50) of GEP being 7.8 h, similar to that of EP. CONCLUSIONS: Paclitaxel and/or its vehicle, Cremophor EL, interferes with the disposition and renal excretion of epirubicin and epirubicinol; gemcitabine has no affect on epirubicin and paclitaxel plasma pharmacokinetics and renal excretion of epirubicin, while neutropenia is not enhanced by gemcitabine
Effects of MK-886 and L-745,337 on growth and apoptosis in human HT-29 colon cancer cells
No full textPharmacogenetics of anticancer drugs in non-Hodgkin lymphomas
Full text linkThe variability of tumour responses to chemotherapeutic agents is a topic of major interest in current oncology research. Advances in the knowledge of molecular pathology of cancer make available strategies by which tumour cells can be profiled for their genetic background in order to select anticancer agents that might selectively kill cells in a molecular context that matches the mechanism of action of drugs. The next generation of anticancer treatments might thus be tailored on the basis of the numerous molecular alterations identified in tumour cells of a particular patient. However, to exploit these alterations, it is necessary to understand how they influence the cellular pathways that control the sensitivity or, conversely, resistance to chemotherapeutic agents. The aim of this article is to outline major genetic abnormalities in non-Hodgkin lymphomas that can be used to streamline anticancer drug selection and to underscore the major role of pharmacogenetics, which studies the interactions between genetic background and drug activity, to the prediction of likelihood of response and identification of potential new targets for pharmacological intervention
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