Inflammatory disease states (infection, arthritis) are associated with reduced drug oxidation by the cytochrome P450 3A system. Many chemotherapy agents are metabolised through this pathway, and disease may therefore influence inter-individual differences in drug pharmacokinetics. The purpose of this study was to assess cytochrome P450 3A function in patients with advanced cancer, and its relation to the acute-phase response. We evaluated hepatic cytochrome P450 3A function in 40 patients with advanced cancer using the erythromycin breath test. Both the traditional C 20min measure and the recently proposed 1/T MAX values were estimated. The marker of acute-phase response, C-reactive protein and the pro-inflammatory cytokines IL-6, IL-1b, TNFa and IL-8 were measured in serum or plasma at baseline. Cancer patients with an acute phase response (C-reactive protein 410 mg l 71 , n=26) had reduced metabolism as measured with the erythromycin breath test 1/ T MAX (Kruskal -Wallis Anova, P=0.0062) as compared to controls (C-reactive protein 410 mg l 71 , n=14) . Indeed, metabolism was significantly associated with C-reactive protein over the whole concentration range of this acute-phase marker (r=70.64, Spearman Rank Correlation, P50.00001). C-reactive protein serum levels were significantly correlated with those of IL-6 (Spearman coefficient=0.58, P50.0003). The reduction in cytochrome P450 3A function with acute-phase reaction was independent of the tumour type and C-reactive protein elevation was associated with poor performance status. This indicates that the sub-group of cancer patients with significant acute-phase response have compromised drug metabolism, which may have implications for the safety of chemotherapy in this population.
Depletion of nutritional reserves and significant weight loss can lead to an increased risk of morbidity, reduced chemotherapy response, and shorter survival in patients with cancer. Weight loss and malnutrition are recognized to result from multifactorial processes, which if assessed and managed appropriately may lead to improved treatment outcome. Numerous methodologies are used for the assessment of nutritional status. However, it remains unclear which of these tools is the most appropriate in the setting of cancer chemotherapy. The aim of this study was to investigate the use of various fundamental assessment tools that could be applied to the routine clinical evaluation of nutritional status in patients with advanced solid malignancies before treatment with palliative chemotherapy. We investigated the interrelationships between biochemical indices, anthropometric measures, and a nutritional screening tool, the Mini-Nutritional Assessment, in 73 patients. Many of these measures were highly interrelated, but the baseline history of weight loss in these patients was strongly correlated to the Mini-Nutritional Assessment (MNA) score (P < 0.0005). In turn, baseline weight loss and the MNA score were strongly correlated to serum C-reactive protein (a marker of acute-phase response). In some patients, malnutrition was linked to disease- or treatment-related upper digestive tract morbidity. Testing for the serum concentration of C-reactive protein at baseline may identify a subset of patients for whom a decline in nutritional status is linked to the presence of an active inflammatory response, a recognized precursor of cachexia
AimsPrevious pharmacokinetic studies of the 3-weekly regimen (100 mg m -2 every 3 weeks) of docetaxel have shown that docetaxel clearance is affected by liver function, body surface area, age, serum a 1 -acid glycoprotein and cytochrome P450 3A4 (CYP3A4) activity. However, the pharmacokinetics of a weekly docetaxel (40 mg m -2 week -1 ) schedule are not well characterized. The aims of this study were (a) to investigate the pharmacokinetics of docetaxel (40 mg m -2 week -1 ) using sparse concentration-time data collected from patients with advanced cancer and (b) to utilize a population pharmacokinetic approach to identify patient covariates that significantly influence the clearance of docetaxel when administered according to this regimen. MethodsA two-compartment pharmacokinetic model was used to describe the doceta xel concentration-time data from 54 patients with advanced cancer. The mean population and individual posterior Bayesian estimates of docetaxel clearance were estimated using P-PHARM. The relationships between docetaxel clearance and 21 covariates were investigated. This included estimates of CYP3A4 function in each patient using the erythromycin breath test (1/ t max ). Significant covariates were included into the final population pharmacokinetic model. Pharmacokinetic models were validated using a data splitting approach with a dataset consisting of 16 patients. ResultsSignificant relationships were found between docetaxel clearance and 1/ t max (erythromycin breath test parameter) and several of the liver function enzymes and CL was best described by the equation; CL = 21.51 + 217 (1/ t max ) -0.13 (ALT). This final population pharmacokinetic model provided both precise and unbiased predictions of docetaxel concentrations in a validation group of patients and an estimate of the population mean (95% confidence interval) clearance of docetaxel was 30.13 l h -1 (12.54, 46.04 l h -1 ) with an intersubject variability 30%. ConclusionsA population pharmacokinetic model has been developed and validated for weekly docetaxel (40 mg m -2 ) in patients with advanced cancer. These results indicate that CYP3A4 activity and hepatic function have an impact on the pharmacokinetics of docetaxel when administered weekly. Population pharmacokinetics of weekly docetaxelBr J Clin Pharmacol 57 :1 45
The erythromycin breath test (EBT) is a putative probe of cytochrome P450 (CYP) 3A4 activity in vivo. Therefore, the EBT might prove useful for the individualisation of doses of drugs that have a low therapeutic window (for example the immunosuppressants or cytotoxics) and are metabolised by CYP3A4. However, there is a lack of consensus as to how the EBT should be used to predict total body clearance (CL), and the results so far have been largely disappointing. We argue that the required assumption that individuals produce 5 mmol of CO2/min per m2 at rest is one of the problems with the existing EBT, as the literature suggests significant variability and possible gender differences in this parameter. An examination of the EBT with a simple compartment model suggests that alternative parameters could be more useful in the prediction of CL. In particular, there is theoretical support for the use of the time-point at which breath radioactivity is maximal (tmax) as a correlate for CL. This is in agreement with our recent study of the pharmacokinetics of erythromycin in patients with cancer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.