Influence of capecitabine absorption on its metabolites pharmacokinetics: a bioequivalence study

Re-thinking the possible interaction between proton pump inhibitors and capecitabine

Proton Pump Inhibitors (PPI) rank within the top ten most prescribed medications in Europe and USA. A high frequency of PPI use has been reported amongst patients undergoing chemotherapy, to mitigate treatment-induced gastritis or gastro-oesophageal reflux. Several recent, mostly retrospective, observational studies have reported inferior survival outcomes among patients on capecitabine who concomitantly use PPI. Whilst this association is yet to be definitively established, given the prominence of capecitabine as an anti-cancer treatment with multiple indications, these reports have raised concern within the oncological community and drug regulatory bodies worldwide. Currently, the leading mechanism of interaction postulated in these reports has focussed on the pH altering effects of PPI and how this could diminish capecitabine absorption, leading to a decrease in its bioavailability. In this discourse, we endeavour to summarise plausible pharmacokinetic interactions between PPI and capecitabine. We provide a basis for our argument against the currently proposed mechanism of interaction. We also highlight the long-term effects of PPI on health outcomes, and how PPI use itself could lead to poorer outcomes, independent of capecitabine.

[Recommendations for using oral antineoplastic and immunomodulating agents in oncohematology by enteral tube administration]

INTRODUCTION AND OBJECTIVE

in recent years, the number of oral antineoplastic and immunomodulating drugs in oncohematology has increased enormously. Often, these drugs must be administered to patients with enteral tube feeding or swallowing disorders, which causes safety problems when handling these drugs (many of them are classified as hazardous drugs). In addition, it is important to note that the administration of these drugs can also interact with enteral nutrition (EN). The objective of this study was to review and update the recommendations for the administration and handling of oral antineoplastic and immunomodulating drugs.

METHOD

a Working Group made up of pharmacists from the Pharmacy Group of The Spanish Society of Clinical Nutrition and Metabolism (SENPE) and the Clinical Nutrition Group of The Spanish Society of Hospital Pharmacy (SEFH) was created. A bibliographic review was carried out between 2015 and 2020 on the administration and handling of oral antineoplastic and immunomodulating drugs in oncohematology. The information about pharmaceutical specialties, dosage, presentation, brand names, instructions for oral or enteral tube administration, interactions with EN, precautions, and remarks for handling and administration was analyzed.

RESULTS

a total of 77 active principles and 84 pharmaceutical forms were included. Recommendations and instructions for oral, nasogastric tube, and gastrostomy administration, handling of the antineoplastic and immunomodulating drugs, and interactions with EN were described.

CONCLUSIONS

the handling and administration information about the oral antineoplastic and immunomodulating drugs currently used in oncohematology for people with enteral accesses or swallowing disorders is limited. It is important to perform post-marketing studies to ensure a safe and effective administration of these drugs.

Concomitant Use of Proton Pump Inhibitors With Capecitabine Based Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Cancer: Is it Safe?

AIM

Capecitabine (Cape) is routinely used for the neoadjuvant chemoradiation treatment (NACRT) of locally advanced rectal cancers (LARCs). Previous reports have suggested that the concomitant use of proton pump inhibitors (PPIs) may affect the efficacy of Cape, although the true effect of PPIs when used with Cape as a radiosensitizer for neoadjuvant radiation is unclear. The aim of our study was to evaluate the impact of concurrent PPI use along with fluorouracil (FU) and Cape based NACRT in terms of pathologic and oncological outcomes, in patients with LARC.

METHODS

LARC patients treated at our center with NACRT from 2010 to 2016 were identified. Postoperative pathology and follow-up outcomes were examined for any differences with relation to the use of PPIs concurrently with FU and Cape based NACRT and adjuvant chemotherapy regimens.

RESULTS

Three hundred four and 204 patients received treatment with FU and Cape based NACRT. No difference in pathologic complete response rate was noted between the 2 arms with the concurrent use of PPIs (25.8% and 25%, respectively, P=0.633); or with and without the use of PPIs in the Cape-NACRT arm specifically (20% and 20.7%, P=0.945). At a median follow-up of 5 years, no statistical difference in local or distant control was noted in the Cape-NACRT patients, with and without concomitant PPI use (P=0.411 and 0.264, respectively).Multivariate analysis showed no association of PPI use and NACRT with Cape, in terms of local control (hazard ratio=0.001, P=0.988) or overall survival (hazard ratio=1.179, confidence interval=0.249-5.579, P=0.835).

CONCLUSIONS

Our study revealed that there was no adverse pathologic or oncological outcome with the concurrent use of PPIs along with Cape-NACRT in the treatment of LARC. We report that it may be safe to use PPIs if essential, in this clinical setting, although it would be wise to exercise caution.

A Validated Stability-Indicating HPTLC Method for the Estimation of Capecitabine in its Tablet Dosage Form

Background:

Capecitabine is an orally available prodrug of 5-flurouracil used in the treatment of breast cancer, metastatic colorectal cancer and stage III colorectal cancer. Various studies have reported the HPLC, HPLC-MS, MS/MS methods for estimation of capecitabine. However, till date HPTLC method for estimation of capecitabine and its validation is not reported in tablet dosage form.

Introduction:

Presented study deals with the development and validation of stability indicating high performance thin layer chromatography method for the determination of Capecitabine in tablet dosage form.

Methods:

The method was developed using precoated HPTLC plates with silica gel 60 F254 as stationary phase and toluene-methanol the ratio of 7.5:2.5 v/v as the mobile phase. Capecitabine (RF 0.48 ± 0.03) and its degradation products were well resolved. The wavelength selected for study was 240 nm. The method was linear in the concentration range 50–550 ng/band with a correlation coefficient of 0.994. The repeatability for six samples was 1.25% RSD. The intraday and interday precisions were 1.46-1.71%RSD and 1.31-1.67% RSD, respectively. The accuracy (recovery) was found to be in the range of 99.10-101.23% with LOD and LOQ were found to be 0.650 and 1.765 mg/band. The mean content of drug in tablet dosage form was found to be 101.51% with a % RSD of 1.20. The drug was subjected to stress conditions such as hydrolysis, oxidation, photolysis, and heat.

Results:

Degradation products produced as a result of the stress conditions did not interfere with the detection of Capecitabine; therefore, the proposed technique can be considered stability-indicating. Capecitabine did not degrade under thermal and photolytic conditions but showed degradation under acidic and alkaline conditions with 15 and 11% decompositions respectively.

Conclusion:

The developed method was found to be facile, simple, specific, precise, and stabilityindicating. It can be employed for the routine analysis of capecitabine in tablet dosage form.

Pharmacokinetic analysis of metronomic capecitabine in refractory metastatic colorectal cancer patients

The aim of the present study was to assess the pharmacokinetics (PK) of metronomic capecitabine and its metabolites in a population of refractory metastatic colorectal cancer (mCRC) patients. Thirty-four patients (M/F, 22/12) with a diagnosis of mCRC received capecitabine 800 mg p.o. twice a day and cyclophosphamide 50 mg/day p.o. Blood samples were collected at baseline, 15 min, 30 min, 1 h, 1.5 h, 2 h, 3 h and 5 h at day 1 after capecitabine administration. Plasma concentrations of capecitabine and its metabolites were measured by high performance liquid chromatography and the main PK parameters were calculated. Maximum plasma concentrations (C_max) of capecitabine (11.51 ± 9.73 μg/ml) occurred at 0.5 h, whereas the C_max of 5'-deoxy-5-fluorocytidine (5'-DFCR; 2.45 ± 2.93 μg/ml), 5'-deoxy-5-fluorouridine (5'-DFUR; 6.43 ± 8.2 μg/ml), and 5-fluorouracil (5-FU; 0.24 ± 0.16 μg/ml) were found at 1 h, 1.5 h and 1 h, respectively. Capecitabine, 5'-DFCR, 5'-DFUR and 5-FU AUCs at day 1 were 21.30 ± 10.78, 5.2 ± 4.6, 19.59 ± 3.83 and 0.66 ± 0.77 hxμg/ml, respectively. In conclusion, low doses of capecitabine were rapidly absorbed and extensively metabolized, achieving measurable plasma concentrations in a heavily pretreated population of patients.

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

PURPOSE

To describe concentration versus time profiles of capecitabine and its metabolites 5'-DFUR, 5'-DFCR and 5-FU, depending on tablet formulation and on frequent and/or relevant genetic polymorphisms of cytidine deaminase, dihydropyrimidine dehydrogenase, thymidylate synthase and methylenetetrahydrofolate reductase (MTHFR).

METHODS

In 46 cancer patients on chronic capecitabine treatment, who voluntarily participated in the study, individual therapeutic doses were replaced on four consecutive mornings by the study medication. The appropriate number of 500 mg test (T) or reference (R) capecitabine tablets was given in randomly allocated sequences TRTR or RTRT (replicate design). Average bioavailability was assessed by ANOVA.

RESULTS

Thirty female and 16 male patients suffering from gastrointestinal or breast cancer (mean age 53.4 years; mean dose 1739 mg) were included. The T/R ratios for AUC0-t(last) and C max were 96.7 % (98 % CI 90.7-103.2 %) and 87.2 % (98 % CI 74.9-101.5 %), respectively. Within-subject variability for AUC0-t(last) and C max (coefficient of variation for R) was 16.5 and 30.2 %, respectively. Similar results were seen for all metabolites. No serious adverse events occurred. For the MTHFR C677T (rs1801133) genotype, an increasing number of 677C alleles showed borderline correlation with an increasing elimination half-life of capecitabine (p = 0.043).

CONCLUSIONS

The extent of absorption was similar for T and R, but the rate of absorption was slightly lower for T. While such differences are not considered as clinically relevant, formal bioequivalence criteria were missed. A possible, probably indirect role of the MTHFR genotype in pharmacokinetics of capecitabine and/or 5-FU should be investigated in further studies.

Drug administration via enteral tubing: an unresolved but increasing challenge

The number of patients with serious impairments of the swallowing function will continue to increase in the coming decades. Problems related to enteral feeding and drug administration to patients with swallowing issues is a growing concern of physicians, compounding pharmacists and nurses. The lack of information on the impact of compounding by mixing with liquid or food and/or administering through enteral or intestinal feeding tubes on the drug product safety and efficacy is problematic. In addition, there is a lack of appropriate alternative dosage forms of drugs for these routes of administration. As patients with swallowing issues represent a significant and growing patient population that is vulnerable and in need of effective drug therapy, the issue needs urgent attention by all stakeholders involved in healthcare provision. Incremental improvements at the different stages in the process, from product development to the patients' well-being are required to assure safe and effective drug therapy to an important patient population.

Cabazitaxel: more than a new taxane for metastatic castrate-resistant prostate cancer?

The taxanes are recognized as a major class of chemotherapeutic agents; however, mechanisms of innate and acquired resistance can limit their usefulness. Cabazitaxel, a novel taxane with microtubule-stabilizing potency similar to docetaxel, exhibits activity against tumor cell lines resistant to paclitaxel and docetaxel. Cabazitaxel showed linear pharmacokinetics and a terminal elimination half-life comparable with that of docetaxel, findings which support dosing as a single infusion in three-week treatment cycles. Dose-ranging studies recommended doses of 20 or 25 mg/m(2) every three weeks. Antitumor activity was shown in patients with advanced cancer and chemotherapy failure (including taxane failure). Other early studies investigated the efficacy of cabazitaxel in pretreated metastatic breast cancer, either as a single agent or in combination with capecitabine. Objective antitumor response rates of up to 24% and sustained tumor stabilizations were also observed. The TROPIC phase III study, conducted in patients with metastatic castrate-resistant prostate cancer previously treated with docetaxel, established cabazitaxel as the first chemotherapeutic agent to offer a survival advantage in this patient population. Across these studies, the dose-limiting hematologic toxicity was neutropenia (including febrile neutropenia), usually controllable with colony-stimulating factor/granulocyte-colony stimulating factor support.

A multicentre dose-escalating study of cabazitaxel (XRP6258) in combination with capecitabine in patients with metastatic breast cancer progressing after anthracycline and taxane treatment: a phase I/II study

BACKGROUND

Most patients with metastatic breast cancer (MBC) progress after chemotherapy. Cabazitaxel (XRP6258) is a new taxoid that is active in chemotherapy-resistant tumour cell lines. The objectives of this phase I/II study were to assess the maximum tolerated dose (MTD), safety profile, pharmacokinetics, and activity of cabazitaxel plus capecitabine in patients with MBC who had been previously treated with taxanes and anthracyclines.

PATIENTS AND METHODS

In part I, we used a 3+3 dose-escalation scheme to assess the MTD of intravenous cabazitaxel (day 1) with oral capecitabine twice daily (days 1-14) every 3 weeks. In part II, we evaluated the objective response rate (ORR) at the MTD.

RESULTS

Thirty-three patients were enrolled and treated (15 in part I; 18 in part II). Cabazitaxel 20mg/m(2) plus capecitabine 1000 mg/m(2) was the MTD. Pharmacokinetic analysis showed no apparent drug-drug interaction. In all patients, the main grade 3-4 toxicities were asthenia (n=5), hand-foot syndrome (n=5), neutropenia (n=21), neutropenic infection (n=1), and neutropenic colitis (n=1). One patient had febrile neutropenia. Antitumour activity was observed at all dose-levels with two complete responses, five partial responses (PRs), and 20 disease stabilisations (seven unconfirmed PR). At the MTD, 21 patients were evaluable for efficacy. The ORR was 23.8% (95% CI: 8.2-47.2%). The median response duration was 3.1 months (95% CI: 2.1-8.4 months), with four of five lasting for more than 3 months. Median time to progression was 4.9 months.

CONCLUSIONS

Cabazitaxel combined with capecitabine is active, has a safety profile consistent with a taxane plus capecitabine combination and warrants further investigation in patients with MBC.

An APCI LC-MS/MS method for routine determination of capecitabine and its metabolites in human plasma

The anticancer drug capecitabine and its metabolites [including the active metabolite 5-fluorouracil (5-FU)] display high pharmacokinetic inter-patient variability. Such variability, which may lead to treatment failure or toxicity, could need drug concentration measurement to individualize dosing regimen. However, usual assay methods are often long and fastidious. A simultaneous and cost-effective method was thus developed for the determination of the concentrations of these compounds in human plasma. Compounds were extracted via a classic liquid-liquid extraction. Chromatographic analysis was performed on a C18 reverse phase column with detection by atmosphere pressure chemical ionization LC-MS/MS. Our method allows a good chromatographic separation of the compounds and was fully validated following Food and Drug Administration (FDA) recommendations (good selectivity, no carry-over, linearity of the calibration curves without weighting, deviations from nominal concentrations of standard samples lower than 15%, intra- and inter-assay precision and accuracy lower than 15%). Recovery and stability were also acceptable following the FDA guidelines. A matrix effect impairing the determination of 5-FU was avoided by using a stable isotopic derivative of 5-FU as internal standard. Interestingly, this method allows detection of TetraHydroUridine, an inhibitor of ex vivo degradation of metabolites, which is essential for the stability, the adequate conditioning of blood samples and for good laboratory practice, essential in routine determination. This method seems usable to routinely determine concentrations of capecitabine and its metabolites in blood and may be helpful in further studies aiming at performing therapeutic drug monitoring.