35 research outputs found
A pharmacometrics model to define docetaxel target in early breast cancer
Aims: We aimed to study the relation between pharmacokinetics (PK) and pharmacodynamics (PD) of docetaxel in early breast cancer and recommend a target exposure.
Methods: A PK/PD study was performed in 27 early breast cancer patients treated with doxorubicin and cyclophosphamide for 4 cycles followed by 4 cycles of docetaxel 75-100 mg/m2 infused every 21 days. Individual Bayesian estimates of docetaxel PK parameters were obtained using a nonparametric population PK model developed with data from patients with metastatic breast cancer who received dose-intensified docetaxel (300-350 mg/m2 ). Docetaxel area under the curve (AUC) and maximum concentration (Cmax) in each cycle and total cumulative AUC (AUCcum) were calculated and related to the incidence of adverse effects and tumour recurrence.
Results: Docetaxel clearance showed no change over the 4 treatment cycles, but a gradual increase in the volume of distribution was observed. One third of the patients had at least 1 dose reduction of docetaxel due to toxicity. The mean AUC, AUCcum and Cmax in patients showing docetaxel-associated adverse events were significantly higher than in patients free of toxicity (P 4.5 mg*h/L and 3.5 mg/L, respectively, were risk factors for docetaxel toxicity, while an AUC <4.5 mg*h/L was associated with tumour recurrence.
Conclusion: We report for the first time a relation between docetaxel exposure and toxicity and recommend specific targets of drug exposure with implications for the clinical management of early breast cancer patients
Methotrexate Pharmacokinetics and Survival in Osteosarcomat
The aim of this study was to analyze the relationship between
exposure to high-dose methotrexate (HDMTX) and tumor response in terms of
survival in children with osteosarcoma. PROCEDURE: This study included 44
patients (479 courses) who received a median dose of 5.92 g/m2 of MTX
(interquartile range (IQR) 2.37 g/m2) in a 4-hr infusion. The mean area under the
concentration-time curve (AUC) estimated by parametric methods (non-parametric
expectation maximization, NPEM), and the mean concentration at the end of the
infusion were considered to be the exposure parameters. Tumor response was
recorded as disease-free survival (DFS), overall survival (OS), and histologic
tumor response. The relationship between MTX exposure and survival parameters was
analyzed by Cox regression. RESULTS: The group of 11 patients who were the least
exposed to MTX (AUC <2,400 micromol/L hr) presented a high DFS, probably due to
the shorter interval of time between MTX courses that led to a higher dose
density. In patients with AUC >2,400 micromol/L hr, an increase in the AUC was
related to an increase in the DFS. Significant differences were observed in the
DFS between patients whose mean AUC was below or above 4,000 micromol/L hr
(P=0.024), such that 4,000 micromol/L hr was considered as the minimum AUC to be
aimed at for future patients. CONCLUSIONS: Dose density seems to be an important
factor in osteosarcoma response, but this must be confirmed in further studies.
In order to improve the response to osteosarcoma in children, it is recommended
that the dose of MTX to be increased such as to obtain an AUC higher than 4,000
micromol/L hr
Mining Small Routine Clinical Data: A Population Pharmacokinetic Model and Optimal Sampling Times of Capecitabine and its Metabolites
Purpose: The present study was performed to demonstrate that small amounts of routine clinical data allow to generate valuable knowledge. Concretely, the aims of this research were to build a joint population pharmacokinetic model for capecitabine and three of its metabolites (5-DFUR, 5-FU and 5-FUH2) and to determine optimal sampling times for therapeutic drug monitoring.
Methods: We used data of 7 treatment cycles of capecitabine in patients with metastatic colorectal cancer. The population pharmacokinetic model was built as a multicompartmental model using NONMEM and was internally validated by visual predictive check. Optimal sampling times were estimated using PFIM 4.0 following D-optimality criterion.
Results: The final model was a multicompartmental model which represented the sequential transformations from capecitabine to its metabolites 5-DFUR, 5-FU and 5-FUH2 and was correctly validated. The optimal sampling times were 0.546, 0.892, 1.562, 4.736 and 8 hours after the administration of the drug. For its correct implementation in clinical practice, the values were rounded to 0.5, 1, 1.5, 5 and 8 hours after the administration of the drug.
Conclusions: Capecitabine, 5-DFUR, 5-FU and 5-FUH2 can be correctly described by the joint multicompartmental model presented in this work. The aforementioned times are optimal to maximize the information of samples. Useful knowledge can be obtained for clinical practice from small databases
Información de medicamentos a la población desde el Servicio de Farmacia a través de Internet
Objectives: To describe and discuss the work of a Pharmacy
Department for the health-care portal www.viatusalud.com.
Methods: Using a web portal, a Pharmacy Department develops
and updates a vademecum on drugs, and answers enquiries
by end-users.
Results: On December 31, 2002 more than 750 records on
drugs were available, and 3030 enquiries had been answered.
Conclusions: With this drug information and online enquiry
service, our Pharmacy Department helps meet the demand of
health-care information posed by the community and by patients
previously seen at Clínica Universitaria. In addition, it allows areas
of improvement to be detected in the information to be offered to
patients fron a Pharmacy Department, and represents a tertiary
source of information for health-care professionals
Effects of dexmedetomidine on subthalamic local field potentials in parkinson's disease
Background: Dexmedetomidine is frequently used for sedation during deep brain stimulator implantation in patients with Parkinson's disease, but its effect on subthalamic nucleus activity is not well known. The aim of this study was to quantify the effect of increasing doses of dexmedetomidine in this population.
Methods: Controlled clinical trial assessing changes in subthalamic activity with increasing doses of dexmedetomidine (from 0.2 to 0.6 μg kg-1 h-1) in a non-operating theatre setting. We recorded local field potentials in 12 patients with Parkinson's disease with bilateral deep brain stimulators (24 nuclei) and compared basal activity in the nuclei of each patient and activity recorded with different doses. Plasma levels of dexmedetomidine were obtained and correlated with the dose administered.
Results: With dexmedetomidine infusion, patients became clinically sedated, and at higher doses (0.5-0.6 μg kg-1 h-1) a significant decrease in the characteristic Parkinsonian subthalamic activity was observed (P<0.05 in beta activity). All subjects awoke to external stimulus over a median of 1 (range: 0-9) min, showing full restoration of subthalamic activity. Dexmedetomidine dose administered and plasma levels showed a positive correlation (repeated measures correlation coefficient=0.504; P<0.001).
Conclusions: Patients needing some degree of sedation throughout subthalamic deep brain stimulator implantation for Parkinson's disease can probably receive dexmedetomidine up to 0.6 μg kg-1 h-1 without significant alteration of their characteristic subthalamic activity. If patients achieve a 'sedated' state, subthalamic activity decreases, but they can be easily awakened with a non-pharmacological external stimulus and recover baseline subthalamic activity patterns in less than 10 min
Therapeutic drug monitoring of neoadjuvant mFOLFIRINOX in resected pancreatic ductal adenocarcinoma
Background: Despite a potentially curative treatment, the prognosis after upfront surgery and adjuvant
chemotherapy for patients with resectable pancreatic ductal adenocarcinoma (PDAC) is poor. Modified
FOLFIRINOX (mFOLFIRINOX) is a cornerstone in the systemic treatment of PDAC, including the neoadjuvant setting. Pharmacokinetic-guided (PKG) dosing has demonstrated beneficial effects in other
tumors, but scarce data is available in pancreatic cancer.
Methods: Forty-six patients with resected PDAC after mFOLFIRINOX neoadjuvant approach and included
in an institutional protocol for anticancer drug monitoring were retrospectively analyzed. 5-Fluorouracil
(5-FU) dosage was adjusted throughout neoadjuvant treatment according to pharmacokinetic parameters and Irinotecan (CPT-11) pharmacokinetic variables were retrospectively estimated.
Results: By exploratory univariate analyses, a significantly longer progression-free survival was observed
for patients with either 5-FU area under the curve (AUC) above 28 mcgh/mL. In the multivariate analyses adjusted by age, gender, performance status and resectability
after stratification according to both pharmacokinetic parameters, the risk of progression was significantly reduced in patients with 5-FU AUC 28 mcgh/mL [HR ¼ 0.189, 95% CI 0.073e0.486, p ¼ 0.001].
Conclusions: Pharmacokinetically-guided dose adjustment of standard chemotherapy treatments might
improve survival outcomes in patients with pancreatic ductal adenocarcinoma
Optimización posológica de 5-fluorouracilo en pacientes con cáncer gastrointestinal
El objetivo principal es caracterizar la disposición de 5-FU en pacientes con cáncer gastrointestinal avanzado, incluyéndose pacientes con cáncer colorrectal, cáncer de páncreas y cáncer gastroesofágico, dependientes del Servicio de Oncología Médica de la Clínica Universidad de Navarra, y relacionar los parámetros farmacocinéticos del citostático con su toxicidad y eficacia.
Se pretende incorporar los resultados de este trabajo en la optimización posológica de 5-FU en la rutina asistencial mediante su monitorización terapéutica
Optimización posológica de 5-fluorouracilo en pacientes con cáncer gastrointestinal
El objetivo principal es caracterizar la disposición de 5-FU en pacientes con cáncer gastrointestinal avanzado, incluyéndose pacientes con cáncer colorrectal, cáncer de páncreas y cáncer gastroesofágico, dependientes del Servicio de Oncología Médica de la Clínica Universidad de Navarra, y relacionar los parámetros farmacocinéticos del citostático con su toxicidad y eficacia.
Se pretende incorporar los resultados de este trabajo en la optimización posológica de 5-FU en la rutina asistencial mediante su monitorización terapéutica