Pharmacokinetics and pharmacogenetics of capecitabine and its metabolites following replicate administration of two 500 mg tablet formulations

Dihydromyricetin reverses capecitabine-induced peripheral myelin dysfunction through modulation of oxidative stress

Previous clinical reports have shown that capecitabine, an oral prodrug of 5-fluorouracil (5-Fu), can induce peripheral neuropathy, resulting in numbness, paresthesia and hypoesthesia. However, the mechanism through which capecitabine causes peripheral nerve injury remains unclear. Here, we demonstrate that systemic administration of capecitabine leads to myelin abnormalities in the peripheral nerves of mice, which are possibly attributed to the death of Schwann cells, the myelinating cells in the peripheral nervous system. Furthermore, our results show that 5-Fu induces significant oxidative stress in Schwann cells by inhibiting the expression of the anti-oxidative protein DJ-1, leading to a decrease in Schwann cell markers. We found that the anti-oxidant dihydromyricetin (DMY) reverses 5-Fu-induced Schwann cell death and oxidative stress and alleviates capecitabine-induced myelin abnormalities. Taken together, our data indicate that capecitabine induces peripheral myelin dysfunction by regulating DJ-1-mediated oxidative stress in Schwann cells and reveal DMY as a potential therapeutic strategy for capecitabine-induced peripheral neuropathy.

Evaluation of bioequivalence and safety analysis of capecitabine tablets and Xeloda® under postprandial dosing conditions in Chinese patients with solid tumor

OBJECTIVES

To compare the pharmacokinetic and safety of the test group capecitabine tablets (0.5 g) and the reference group capecitabine tablets (0.5 g).

METHODS

This study was registered at www.chinadrugtrials.org.cn under the registration number CTR20220138. 48 subjects with solid tumor were recruited and randomized to receive either the test group or the reference group at a dose of 2 g per cycle for three cycles of the entire trial.

RESULTS

The point estimate of the geometric mean ratio of Cmax for the subject and reference groups was 1.0670, which was in the range of 80.00%-125.00%. And the upper limit of 95% confidence interval was -0.0450 < 0. The statistics of geometric mean ratio of AUC0-t and AUC0-∞ (test group/reference group) and their 90% confidence intervals were in the range of 80.00%-125.00%, thus the test group was bioequivalent to the reference group under the conditions of this postprandial test. There were no major or serious adverse events. Conclusion: The pharmacokinetic profiles of capecitabine under postprandial conditions were consistent between the two groups. The two groups were bioequivalent and had a similar favorable safety profile in Chinese patients with solid tumor.

Pharmacokinetic and bioequivalence study of two capecitabine tablets in Chinese patients with breast, colorectal or gastric cancer under fed condition: A multicentric, randomized, open-label, single-dose, two-period, two-way crossover clinical trial

OBJECTIVE

The aim of this study was to examine the pharmacokinetics, bioequivalence, and safety of two tablet formulations of capecitabine 500 mg in Chinese patients with breast, colorectal or gastric cancer under fed condition.

METHODS

A multicentric, randomized, open-label, single-dose, two-period, two-way crossover trial was conducted by randomizing a single oral dose of test (T) or reference (R, Xeloda®) capecitabine (500 mg) to patients of either sex with colon, colorectal or breast cancer under fed condition (high-fat and high-calorie diet). Pharmacokinetic parameters were calculated using non-compartmental methods. Patients were monitored for safety and tolerability throughout the study.

RESULTS

74 subjects were randomly enrolled. The T/R geometric mean ratios (GMRs) and 90% confidence intervals (CIs) for C_max, AUC_0-t and AUC_0-∞ of capecitabine were 96.60% (85.87-108.67%), 99.07% (95.40-102.89%), 99.17% (95.29-103.21%), respectively. All 90% CIs fell within the bioequivalence acceptance range of 80.00-125.00%. The common adverse events (AEs) included clinically significant laboratory abnormalities and gastrointestinal diseases. There were no serious adverse events (SAEs) or deaths during the study. No subject withdrew from the study due to AEs.

CONCLUSION

Single oral intake of test and the reference capecitabine tablets were bioequivalent under fed condition and had similar favourable safety profiles in Chinese patients with breast, colorectal or gastric cancer.

TRIAL REGISTRATION

chinadrugtrials.org.cn (CTR20182110).

Pharmacokinetics and Comparative Bioavailability of Test or Reference Capecitabine and Discrepant Pharmacokinetics Among Various Tumors in Chinese Solid Cancer Patients

The main objective of this study was to compare the pharmacokinetic (PK) bioequivalence of two capecitabine tablets and explore the different PK profiles of various tumors in Chinese patients with cancer. All 76 patients with a confirmed cancer diagnosis were included in this study. A single dose of 2000 mg of test or reference capecitabine (Xeloda, Hoffmann-La Roche) was orally administered postprandially. After 24 hours of washout, the patients were administered the test or the reference capecitabine alternately. PK samples were taken at the time of predose up to 6 hours postdose. Bioequivalence evaluation was performed using the geometric mean ratios of peak concentration in plasma (C_max) , area under the concentration-time curve from time 0 to 6 h (AUC_0-t) , and area under the concentration-time curve from time 0 to infinity (AUC_0-∞ ) for capecitabine and 5-fluorouracil (5-FU). In this study, 90% confidence intervals of test/reference mean ratios of C_max , AUC_0-t , AUC_0-∞ of capecitabine and 5-FU were in the range of 80%-125%. Both the test and reference capecitabine regimens were well tolerated in this study. Furthermore, we found that patients with esophageal-gastrointestinal cancers had higher exposure to capecitabine and a shorter time to C_max (T_max) than those with breast cancer. In conclusion, a single oral dose of 2000 mg of test capecitabine tablets after postprandial administration was bioequivalent to the reference drug.

Pharmacogenetics-based population pharmacokinetic analysis and dose optimization of valproic acid in Chinese southern children with epilepsy: Effect of ABCB1 gene polymorphism

Objective: The aim of this study was to establish a population pharmacokinetic (PPK) model of valproic acid (VPA) in pediatric patients with epilepsy in southern China, and provide guidance for individualized medication of VPA therapy. Methods: A total of 376 VPA steady-state trough concentrations were collected from 103 epileptic pediatric patients. The PPK parameter values for VPA were calculated by using the nonlinear mixed-effects modeling (NONMEM) method, and a one-compartment model with first-order absorption and elimination processes was applied. Covariates included demographic information, concomitant medications and selected gene polymorphisms. Goodness-of-fit (GOF), bootstrap analysis, and visual predictive check (VPC) were used for model evaluation. In addition, we used Monte Carlo simulations to propose dose recommendations for different subgroup patients. Results: A significant effect of the patient age and ABCB1 genotypes was observed on the VPA oral clearance (CL/F) in the final PPK model. Compared with patients with the ABCB1 rs3789243 AA genotype, CL/F in patients with GG and AG genotypes was increased by 8% and reduced by 4.7%, respectively. The GOF plots indicated the satisfactory predictive performance of the final model, and the evaluation by bootstrap and VPC showed that a stable model had been developed. A table of individualized dosing regimens involving age and ABCB1 genotype was constructed based on the final PPK model. Conclusion: This study quantitatively investigated the effects of patient age and ABCB1 rs3789243 variants on the pharmacokinetic variability of VPA. The PPK models could be beneficial to individual dose optimization in epileptic children on VPA therapy.

Clinical evidence of prevention strategies for capecitabine-induced hand-foot syndrome

Hand-foot syndrome (HFS) is the most common adverse effect of capecitabine-containing chemotherapy. The purpose of this study was to assess the efficacies of various prevention and treatment strategies for capecitabine-induced HFS. Searches of the PubMed and Embase databases were performed to identify relevant studies. The risk ratio (RR) with the corresponding 95% confidence interval (CI) was used as an effect measure to evaluate the efficacies of these prevention and treatment strategies. Publication bias was evaluated using Begg's and Egger's tests. Overall and subgroup analyses were conducted. All statistical analyses were conducted with Stata software version 12.0. Seventeen eligible studies were included. Our results indicated that celecoxib was significantly associated with a lower incidence of grade ≥2 capecitabine-induced HFS without heterogeneity (RR = 0.43, 95% CI = 0.23-0.81, I²  = 0.0%). However, pyridoxine and topical urea/lactic acid were not effective toward preventing capecitabine-induced grade 1, 2, 3, ≥1 or ≥2 HFS. Moreover, pyridoxine was not effective in treating capecitabine-induced HFS. Similar results were obtained by subgroup analysis. Our results indicate that celecoxib has potential prophylactic efficacy for capecitabine-induced HFS. However, pyridoxine and topical urea/lactic acid are not associated with a decrease in the incidence of capecitabine-induced HFS.

Genotypes Affecting the Pharmacokinetics of Anticancer Drugs

Cancer treatment is becoming more and more individually based as a result of the large inter-individual differences that exist in treatment outcome and toxicity when patients are treated using population-based drug doses. Polymorphisms in genes encoding drug-metabolizing enzymes and transporters can significantly influence uptake, metabolism, and elimination of anticancer drugs. As a result, the altered pharmacokinetics can greatly influence drug efficacy and toxicity. Pharmacogenetic screening and/or drug-specific phenotyping of cancer patients eligible for treatment with chemotherapeutic drugs, prior to the start of anticancer treatment, can identify patients with tumors that are likely to be responsive or resistant to the proposed drugs. Similarly, the identification of patients with an increased risk of developing toxicity would allow either dose adaptation or the application of other targeted therapies. This review focuses on the role of genetic polymorphisms significantly altering the pharmacokinetics of anticancer drugs. Polymorphisms in DPYD, TPMT, and UGT1A1 have been described that have a major impact on the pharmacokinetics of 5-fluorouracil, mercaptopurine, and irinotecan, respectively. For other drugs, however, the association of polymorphisms with pharmacokinetics is less clear. To date, the influence of genetic variations on the pharmacokinetics of the increasingly used monoclonal antibodies has hardly been investigated. Some studies indicate that genes encoding the Fcγ-receptor family are of interest, but more research is needed to establish if screening before the start of therapy is beneficial. Considering the profound impact of polymorphisms in drug transporters and drug-metabolizing enzymes on the pharmacokinetics of chemotherapeutic drugs and hence, their toxicity and efficacy, pharmacogenetic and pharmacokinetic profiling should become the standard of care.

Evaluating the Feasibility of Use of a Foreign Reference Product for Generic Drug Applications: A Retrospective Pilot Study

BACKGROUND AND OBJECTIVES

The adoption of a domestic reference product in bioequivalence (BE) studies for generic drug applications is required by some countries. The objective of this study is to assess the feasibility of this by investigating whether innovative products from different countries are bioequivalent.

METHODS

Data were collected from all generic drug applications received by the Taiwan regulatory authority 2012-2016. If a submission package contained BE studies, that generic product was compared separately with different reference products, and the resulting data included in this analysis. A method of adjusted indirect comparison was used to evaluate the BE of reference products from different sources. The relationship between in vitro dissolution and in vivo BE was also explored.

RESULTS

The present study included 10 drugs and a total of 11 comparisons. Seven comparisons for maximum concentration (C _max) (63.6%) and all comparisons (100.0%) for area under the curve up to last measurable time point (AUC) complied with the BE criterion. Similar in vitro dissolution profiles were observed in all comparisons. Among the comparisons that failed to demonstrate BE, only one was considered to be possibly related to product difference, with point estimates of indirect comparison for C _max significantly greater than unity (22%). Discordance between in vitro and in vivo observations was probably due to either drugs with highly variable properties or a lack of discriminatory dissolution testing method.

CONCLUSIONS

Although this retrospective analysis only included a few drugs and product formulation types, i.e., immediate release, delayed release, and orally disintegrating tablet, these preliminary results suggest that using a foreign reference product in BE studies for generic drug applications could be a feasible approach, but with some restrictions: comparable dissolution profiles, same innovator company, same size, weight, and type of coating as the domestic reference product, etc. Further investigations for other complex formulations are required.

Assessment of metabolism-dependent drug efficacy and toxicity on a multilayer organs-on-a-chip

This work presents a new and multifunctional organs-on-a-chip device that allows for the characterization of the multi-step metabolism processes of pro-drug CAP in liver cells and its resultant efficacy in multiple target cells simultaneously and quantitatively.