HPLC analysis of mitoxantrone in mouse plasma and tissues: Application in a pharmacokinetic study

Development and Validation of a New High-Performance Liquid Chromatography-Ultraviolet Assay for Quantification of Mitoxantrone in Plasma of BALB/c-nu Mice

The concentration of mitoxantrone in the blood of mice was determined by a high-performance liquid chromatography-ultraviolet method with aloe-emodin as the internal standard. The separation was performed on a Hypersil BDS2 column (4.6 × 250 mm, 5 μm) as the analytical column, the mobile Phase A was acetonitrile, and B was 20-mM potassium dihydrogen phosphate (adding 1% triethylamine and adjusting the pH to 2.8 with phosphoric acid) and 4.6-mM sodium octyl sulfonate. The flow rate was 1.0 mL·min-1, the detection wavelength was 243 nm, the column temperature is 25 ± 5°C and the injection amount was 20 μL. Finally, the linear range of mitoxantrone was 5-200 μg·mL-1, and the correlation coefficient was r = 0.9999. The recovery rate of the method was 91.93-105.5%, and the extraction recovery rate was 91.45-105.5%. The intraday precision and interday precision were <3.29% (limit of detection = 0.3 μg·mL-1). The HPLC method established in this paper was simple, rapid, sensitive and accurate, and can be used to determine the content of mitoxantrone in mouse plasma after tail vein injection.

An eco-friendly matrix-augmented fluorescence spectroscopic approach for the analysis of mitoxantrone, an oncogenic therapy; application to the dosage form and biological matrices

Mitoxantrone (MXN) is a synthetic anthracenedione oncogenic therapy. It is often prescribed as an anticancer agent to manage a variety of cancers. A green, fast, and easy fluorimetric technique for the assay of MXN as a topoisomerase type II enzyme suppressor. An investigation of MXN's fluorescence behavior in various media and solvents constituted the basis for this new technique. Methanol was shown to enhance the intrinsic fluorescence considerably. After excitation at 610 nm, the highest fluorescence intensity was found at 675 nm. Various experimental parameters, such as media, solvents, and pH levels, were tested and adjusted. ICH (International Conference on Harmonization) guidelines were followed when validating procedures. It was possible to achieve linearity in the 0.02-1.50 μg ml^-1 with the method. The sensitivity (in terms of limit of detection and limit of quantification) was 0.003 and 0.008 μg ml^-1 , indicating low toxicity. As a result, the current technology has a remarkable recovery for detecting residues in diverse bodily fluids. Also, the quantum yield was estimated for the designed system. Finally, the method was rated by eco-scale scoring.

Autophagy (but not metabolism) is a key event in mitoxantrone-induced cytotoxicity in differentiated AC16 cardiac cells

Mitoxantrone (MTX) is an antineoplastic agent used to treat advanced breast cancer, prostate cancer, acute leukemia, lymphoma and multiple sclerosis. Although it is known to cause cumulative dose-related cardiotoxicity, the underlying mechanisms are still poorly understood. This study aims to compare the cardiotoxicity of MTX and its' pharmacologically active metabolite naphthoquinoxaline (NAPHT) in an in vitro cardiac model, human-differentiated AC16 cells, and determine the role of metabolism in the cardiotoxic effects. Concentration-dependent cytotoxicity was observed after MTX exposure, affecting mitochondrial function and lysosome uptake. On the other hand, the metabolite NAPHT only caused concentration-dependent cytotoxicity in the MTT reduction assay. When assessing the effect of different inhibitors/inducers of metabolism, it was observed that metyrapone (a cytochrome P450 inhibitor) and phenobarbital (a cytochrome P450 inducer) slightly increased MTX cytotoxicity, while 1-aminobenzotriazole (a suicide cytochrome P450 inhibitor) decreased fairly the MTX-triggered cytotoxicity in differentiated AC16 cells. When focusing in autophagy, the mTOR inhibitor rapamycin and the autophagy inhibitor 3-methyladenine exacerbated the cytotoxicity caused by MTX and NAPHT, while the autophagy blocker, chloroquine, partially reduced the cytotoxicity of MTX. In addition, we observed a decrease in p62, beclin-1, and ATG5 levels and an increase in LC3-II levels in MTX-incubated cells. In conclusion, in our in vitro model, neither metabolism nor exogenously given NAPHT are major contributors to MTX toxicity as seen by the residual influence of metabolism modulators used on the observed cytotoxicity and by NAPHT's low cytotoxicity profile. Conversely, autophagy is involved in MTX-induced cytotoxicity and MTX seems to act as an autophagy inducer, possibly through p62/LC3-II involvement.

Polysialylated nanoinducer for precisely enhancing apoptosis and anti-tumor immune response in B-cell lymphoma

B-cell lymphoma is one of the most common types of lymphoma, and chemotherapy is still the current first-line treatment. However, due to the systemic side effects caused by chemotherapy drugs, traditional regimens have limitations and are difficult to achieve ideal efficacy. Recent studies have found that CD22 (also known as Siglec-2), as a specific marker of B-cells, is significantly up-regulated on B-cell lymphomas. Inspired by the specific recognition and binding of sialic acid residues by CD22, a polysialic acid (PSA)-modified PLGA nanocarrier (SAPC NP) designed to target B-cell lymphoma was fabricated. Mitoxantrone (MTO) was further loaded into SAPC NP through hydrophobic interactions to obtain polysialylated immunogenic cell death (ICD) nanoinducer (MTO@SAPC NP). Cellular experiments confirmed that MTO@SAPC NP could be specifically taken up by two types of CD22⁺ B lymphoma cells including Raji and Ramos cells, unlike the poor endocytic performance in other lymphocytes or macrophages. MTO@SAPC NP was determined to enhance the ICD and show better apoptotic effect on CD22⁺ cells. In the mouse model of B-cell lymphoma, MTO@SAPC NP significantly reduced the systemic side effects of MTO through lymphoma targeting, then achieved enhanced anti-tumor immune response, better tumor suppressive effect, and improved survival rate. Therefore, the polysialylated ICD nanoinducer provides a new strategy for precise therapy of B-cell lymphoma. STATEMENT OF SIGNIFICANCE: • Polysialic acid functionalized nanocarrier (SAPC NP) was designed and prepared. • SAPC NP is specifically endocytosed by two CD22⁺ B lymphoma cells. • Mitoxantrone-loaded nanoinducer (MTO@SAPC NP) promote immunogenic cell death and anti-tumor immune response. • "Polysialylation" is a potential new approach for precision treatment of B-cell lymphoma.

A simple single jar “on–off fluorescence” designed system for the determination of mitoxantrone using an eosin Y dye in raw powder, vial, and human biofluids

This work describes a green fluorescence on–off system that relies on establishing a simple ion association complex pairing the mitoxantrone antineoplastic drug with the eosin Y reagent in a slightly acidic solution.

A single-center, self-controlled, phase I clinical trial of mitoxantrone hydrochloride injection for lymph tracing for sentinel lymph node identification of breast cancer

Background

Mitoxantrone hydrochloride injection for lymph tracing (MHI) is a novel lymphatic tracer for sentinel lymph node (SLN) in patients with early breast cancer but exhibited remarkable liver, kidney, and hematologic toxicities in previous studies. Here, the pharmacokinetics and pharmacodynamics profiles of MHI were evaluated to surmise safety and tolerability.

Methods

Phase 1 open-label, single center, and dose escalation study was performed. Ten patients with invasive breast cancer received 0.5, 1.0, or 2.0 mL of MHI into the breast tissues surrounding the tumor for lymphatic mapping. All of these patients were injected with 2 mCi nuclide-labeled sulfur colloid as a self-control 24 to 48 hours before surgery. Safety was assessed by the incidence of adverse events graded by the National Cancer Institute Common Terminology Criteria, version 4.0.3 (CTCAE4.0.3). Blood samples for pharmacokinetic analyses were collected before and after administration at 15, 30, 60, 120, and 240 min of the injection of MHI.

Results

Up to the cutoff date of the study (Aug 8, 2018), no dose-limiting toxic effects or obvious allergic reactions were observed. Only one case of an adverse event was certainly related to MHI, where it caused blue discoloration of the local skin over the injection site after the operation, but this stain gradually went away. The peak level of MHI was achieved after 15-30 min post injection and completely eliminated from the plasma after 60 min. There were no significant differences in the number of lymph nodes detected by MHI and radioactive colloid. Only one patient with lymph node macrometastases had no SLN detected by either the radioactive colloid or the MHI.

Conclusions

At a dose of up to 2.0 mL, MHI was well tolerated and safe for conducting SLN biopsies in patients with breast cancer. Although there was a case with blue discoloration of the local skin over the injection site after the operation, and remained for a short period of time, but the overall safety was acceptable. Here, we approached a novel SLN tracing slant; however, more investigations of MHI should be performed for further evaluations. (Chinadrugtrials.org.cn number: CXHL1301201, Date of registration: October 12, 2015.).

Investigating the interaction of mitoxantrone with anionic surfactants by spectrofluorimetry and its application for the feasible analysis of pharmaceutical preparation and biological fluids

The behaviour of mitoxantrone (MTX), an anthracenedione antineoplastic agent, in different types of organized medium was explored using molecular spectrofluorometry. The original fluorescence and quantum yield of MTX were augmented by about five-fold in the aqueous buffered solution (Britton-Robinson, pH 3.0) by the addition of sodium dodecyl sulfate. Enhancement in the fluorescence intensity did not come from the boost in the ultraviolet (UV) light absorbance of the drug in the presence of micelles but due to shielding of the lowest excited singlet state of the drug from a radiationless process inside the cavity of the micelle. Accordingly, a versatile, sensitive, and feasible spectrofluorimetric method was constructed and evaluated for MTX determination. Fluorescence measurements were performed at 675 nm (λ_ex 610 nm). A linear relationship was shown between fluorescence intensity and drug concentration within the range 0.01-2.0 μg ml^-1 of MTX with a correlation coefficient of 0.9999 and a detection limit of 2 ng ml^-1 . The developed method was effectively used for analysis of MTX in biological samples and dosage forms. In addition, the method was expanded to study the stability of MTX exposed to different drastic degradations and the kinetic parameters of the degradation were calculated.

Polymer micro/nanocarrier-assisted synergistic chemohormonal therapy for prostate cancer

Polymer micro/nanocarrier-assisted chemohormonal therapy upregulates chemotherapy efficacy and down-regulates hormone level, effectively inhibiting the progression of prostate cancer.

Hyaluronic acid/polyethylene glycol nanoparticles for controlled delivery of mitoxantrone

Hyaluronic acid (HA) has inherent ability to target the CD44 receptors and internalize into tumour cells via receptor-mediated endocytosis. Therefore, conjugation of this natural linear polysaccharide to polymeric NPs or micelles, as one of the most promising approaches, could be useful for future clinical applications such as drug delivery. Accordingly, we report on the synthesis of mitoxantrone (MTX)-conjugated polymeric nanoparticles (NPs) composed of polyethylene glycol-HA (PEG-HA) for MTX delivery toward special tumour cells. To determine the size of the polymeric NPs, field emission scanning electron microscopy (FESEM) and particle size analyzer system Zetasizer_nanoZS were employed. The in vitro cytotoxicity analysis of MTX-loaded HA-PEG NPs and free MTX against two cell lines with different levels of CD44 expression (MDA-MB-231 (very high) and MCF-7 (low) was conducted by MTT assay. Also, computational molecular docking was employed to study in detail the active site residues and the critical interactions between HA-EDA-PEG-EDA-MTX NPs and CD44 receptor. The particle size analysis and electron microscopy showed the average size of polymeric NPs less than 350 nm. FT-IR spectrophotometry analysis and also NMR confirmed the conjugation of HA and MTX onto the PEG. Cytotoxicity assay revealed that the engineered polymeric NPs were able to specifically bind to and significantly inhibit the CD44 receptor-positive MDA-MB-231 cells, but not the CD44-negative MCF-7 cells. Furthermore, analysis of the binding modes revealed that for the best-docked pose nearly 10 conventional hydrogen bond can occur between the MTX-EDA-PEG-EDA-HA NPs and amino acids of CD44 receptor. Based on these findings, we suggest the HA-PEG-MTX NPs as an effective functional-targeted nanomedicine toward therapy of CD44-positive cancers.

Upregulation of PDZK1 by Calculus Bovis Sativus May Play an Important Role in Restoring Biliary Transport Function in Intrahepatic Cholestasis

Intrahepatic cholestasis is a main cause of hepatic accumulation of bile acids leading to liver injury, fibrosis, and liver failure. Our previous studies proved that Calculus Bovis Sativus (CBS) can restore biliary transport function through upregulating the multidrug resistance-associated protein 2 (MRP2) and breast cancer resistance protein (BCRP) in 17α-ethynylestradiol- (EE-) induced intrahepatic cholestasis rats. The regulation mechanism of CBS on these transporters, however, remains unclear. This study was designed to evaluate the possible relationship between the effect of CBS on transport activities and the regulation of CBS on the expression of PDZK1, a mainly scaffold protein which can regulate MRP2 and BCRP. Intrahepatic cholestasis model was induced in rats with injection of EE for five consecutive days and then the biliary excretion rates and cumulative biliary excretions were measured. The mRNA and protein expression levels of PDZK1 were detected by reverse transcription-quantitative real-time polymerase chain reaction, western blot, and immunohistochemical analysis. When treated with CBS, cumulative biliary excretions and mRNA and protein expressions of PDZK1 were significantly increased in intrahepatic cholestasis rats. This study demonstrated that CBS exerted a beneficial effect on EE-induced intrahepatic cholestasis rats by restoring biliary transport function, which may result from the upregulation of PDZK1 expression.

Antineoplastic drugs and their analysis: a state of the art review

We provide an overview of the analytical methods available for the quantification of antineoplastic drugs in pharmaceutical formulations, biological and environmental samples.

Multifunctional hyaluronic acid modified graphene oxide loaded with mitoxantrone for overcoming drug resistance in cancer

Multifunctional nanosheets (HA-GO/Pluronic) with targeted chemo-photothermal properties were successfully developed for controlled delivery of mitoxantrone (MIT) to overcome multidrug resistance (MDR). In vitro release profiles displayed that both an acidic environment and a NIR laser could trigger and accelerate the release of a drug, which ensured nanosheets were stable in blood circulation and released MIT within tumor cells under laser irradiation. HA-GO/Pluronic nanosheets were taken up into MCF-7/ADR cells via receptor-mediated endocytosis, which further facilitated escapement of P-gp efflux. Compared with MIT solution, MIT/HA-GO/Pluronic showed greater cytotoxicity and increase in cellular MIT accumulation in MCF-7/ADR cells. Cell apoptosis and cell cycle arrest studies also revealed that MIT/HA-GO/Pluronic was more potent than MIT/GO/Pluronic and MIT solution. The anticancer efficacy in vivo was evaluated in MCF-7 and MCF-7/ADR-bearing mice, and inhibition of tumors by MIT/HA-GO/Pluronic with NIR laser irradiation was the most effective among all MIT formulations. In summary, the MIT/HA-GO/Pluronic system had striking functions such as P-gp reversible inhibitor and anticancer efficacy, and could present a promising platform for drug-resistant cancer treatment.

Study on pharmacokinetics and tissue distribution of the isocorydine derivative (AICD) in rats by HPLC-DAD method

A simple and effective high-performance liquid chromatography with diode-array detection method coupled with a liquid-liquid extraction pretreatment has been developed for determining the pharmacokinetics and tissue distribution of a novel structurally modified derivative (8-acetamino-isocorydine) of isocorydine. According to the in vivo experiments data calculations by DAS 2.0 software, a two-compartment metabolic model was suitable for describing the pharmacokinetic of 8-acetamino-isocorydine in rats. 8-Acetamino-isocorydine was absorbed well after oral administration, and the absolute bioavailability was 76.5%. The half-life of 8-acetamino-isocorydine after intravenous and oral administration was 2.2 h and 2.0 h, respectively. In vivo, 8-acetamino-isocorydine was highly distributed in the lungs, kidney and liver; however, relatively little entered the brain, suggesting that 8-acetamino-isocorydine could not easily pass through the blood brain barrier. Our work describes the first characterization of the pharmacokinetic parameters and tissue distribution of 8-acetamino-isocorydine. The acquired data will provide useful information for the in vivo pharmacology of 8-acetamino-isocorydine, and can be applied to new drug research.

A novel chemiluminescence assay of mitoxantrone based on diperiodatocuprate(III) oxidation

A novel and strong chemiluminescence (CL) of luminol with diperiodatocuprate (K5[Cu(HIO6)2]) was observed in alkaline medium. After the addition of mitoxantrone (MTX) into this system, the CL intensity could be greatly inhibited by MTX. Based on the phenomenon, a sensitive CL method was established for analysis of MTX combining with flow injection technology. Under optimum experimental conditions, the CL intensity was linearly related to the logarithm concentration of MTX from 5.0×10(-9)-1.0×10(-7) g/ml with the detection limit of 1.1×10(-9) g/ml (S/N=3). The relative standard deviation was 1.2% for 5.0×10(-8) g/ml of MTX. The proposed method was successfully applied for determination of MTX in pharmaceutical preparations and biological fluids. The possible CL reaction mechanism was also discussed briefly.

A physiologically based pharmacokinetic model of mitoxantrone in mice and scale-up to humans: a semi-mechanistic model incorporating DNA and protein binding

We conducted a pharmacokinetic (PK) study of mitoxantrone (Novantrone®), a clinically well-established anticancer agent, in mice and developed a mechanism-based PBPK (physiologically based pharmacokinetic) model to describe its disposition. Mitoxantrone concentrations in plasma and six organs (lung, heart, liver, kidney, spleen, and brain) were determined after a 5 mg/kg i.v. dose. We evaluated three different PBPK models in order to characterize our experimental data: model 1 containing Kp values, model 2 incorporating a deep binding compartment, and model 3 incorporating binding of mitoxantrone to DNA and protein. Among the three models, only model 3 with DNA and protein binding captured all the experimental data well. The estimated binding affinity for DNA (K (DNA)) and protein (K (macro)) were 0.0013 and 1.44 μM, respectively. Predicted plasma and tissue AUC values differed from observed values by <19 %, except for heart (60 %). Model 3 was further used to simulate plasma mitoxantrone concentrations in humans for a 12-mg/m(2) dose, using human physiological parameters. The simulated results generally agreed with the observed time course of mitoxantrone plasma concentrations in patients after a standard dose of 12 mg/m(2). In summary, we reported for the first time a mechanism-based PBPK model of mitoxantrone incorporating macromolecule binding which may have clinical applicability in optimizing clinical therapy. Since mitoxantrone is a substrate of the efflux transporters ABCG2 and ABCB1, the incorporation of efflux transporters may also be necessary to characterize the data obtained in low-dose studies.

Analysis of anticancer drugs: a review

In the last decades, the number of patients receiving chemotherapy has considerably increased. Given the toxicity of cytotoxic agents to humans (not only for patients but also for healthcare professionals), the development of reliable analytical methods to analyse these compounds became necessary. From the discovery of new substances to patient administration, all pharmaceutical fields are concerned with the analysis of cytotoxic drugs. In this review, the use of methods to analyse cytotoxic agents in various matrices, such as pharmaceutical formulations and biological and environmental samples, is discussed. Thus, an overview of reported analytical methods for the determination of the most commonly used anticancer drugs is given.

Glucocorticoid regulation of placental breast cancer resistance protein (Bcrp1) in the mouse

Placental breast cancer resistance protein (Bcrp1; encoded by the Abcg2 gene) limits maternal-fetal transplacental transfer of numerous endogenous and exogenous substrates; however, the regulation of placental Abcg2 and Bcrp1 and is not well understood. Placental Abcg2 messenger RNA (mRNA) levels decrease with advancing gestation in the mouse, and this corresponds to increasing levels of maternal and fetal plasma glucocorticoid. Glucocorticoids, including dexamethasone (DEX), downregulate Bcrp1 expression and function in both breast cancer cell lines and the blood-brain barrier in vitro; whether this occurs in the placenta is not known. The potential regulatory role of synthetic glucocorticoids on placental Bcrp1 is of interest, given that approximately 10% of pregnant women are treated with synthetic glucocorticoid for threatened preterm labor. We hypothesized that (1) exposure of pregnant mice to DEX will downregulate placental Abcg2 mRNA and Bcrp1 protein, and (2) results in increased fetal accumulation of [(3)H]mitoxantrone. Pregnant mice were treated with DEX (low-dose: 0.1 mg/kg or high-dose: 1 mg/kg) or vehicle (saline) from embryonic day (E) E9.5 to E15.5 or E12.5 to E18.5. In placentae derived from female fetuses, high-dose DEX significantly downregulated Abcg2 mRNA expression on E15.5 (P < .05) and significantly inhibited Bcrp1 function (P < .05). Similarly, high-dose DEX significantly inhibited Bcrp1 function in the placentae derived from male fetuses (P < .05). In conclusion, there is a dose-dependent regulatory effect of synthetic glucocorticoid on placental Abcg2 mRNA and Bcrp1 function in vivo. Further, it appears that, at the level of Abcg2 gene expression, the female-derived placentae are more susceptible to the effects of DEX than male placentae.

5,7-Dimethoxyflavone and multiple flavonoids in combination alter the ABCG2-mediated tissue distribution of mitoxantrone in mice

PURPOSE

The objective of our study was to investigate the effect of 5,7-DMF on the accumulation of mitoxantrone (MX) in BCRP-expressing normal cells and to investigate its impact on the PK and tissue distribution of MX in mice.

METHODS

The in vitro effect of 5,7-DMF on MX accumulation was examined in MDCK cells transfected with BCRP. The pharmacokinetic and tissue distribution of mitoxantrone, with and without co-administration of 5,7-DMF or multiple flavonoid combinations, were determined in mice.

RESULTS

In the presence of 2.5 μM or 25 μM of 5,7-DMF, the intracellular concentration of MX was significantly increased in MDCK/Bcrp1 and MDCK/BCRP cells, but not in MDCK/Mock cells. The AUC values of MX in several tissues were significantly increased when MX was co-administered with 5,7-DMF. The most substantial elevations of MX AUC in the presence of 5,7-DMF occurred in the liver (94.5%) and kidneys (61.9%), which is in apparent agreement with the relatively high levels of mouse Bcrp1 expression in these two tissues.

CONCLUSIONS

Bcrp1-mediated DMF-MX interactions occur both in vitro and in vivo. 5,7-DMF represents a novel and very promising chemosensitizing agent for the BCRP-mediated MDR due to its low toxicity and potent BCRP inhibition.

Breast cancer-resistance protein (BCRP1) in the fetal mouse brain: development and glucocorticoid regulation

Breast cancer-resistance protein (BCRP1), encoded by Abcg2 mRNA, limits the penetration of a spectrum of compounds into the brain. The fetal brain is a primary target for many BCRP1 substrates; however, the developmental expression, function, and regulation of Abcg2/BCRP1 in the mouse fetal brain are unknown. Synthetic glucocorticoids (e.g., dexamethasone [DEX]) increase Abcg2/BCRP1 expression and function in vitro in endothelial cells derived from brain microvessels. A regulatory role of glucocorticoids on Abcg2/BCRP1 in the fetal brain is of importance given that approximately 10% of pregnant women are treated with synthetic glucocorticoid for threatened preterm labor. We hypothesized the following: 1) Abcg2 mRNA and BCRP1 protein expression increases with development (from Embryonic Day [E] 15.5 to E18.5), corresponding to decreased accumulation of BCRP1 substrate in the fetal brain. 2) Maternal treatment with DEX will up-regulate Abcg2 mRNA and BCRP1 protein expression in the fetal brain, resulting in decreased BCRP1 substrate accumulation. Pregnant FVB dams were euthanized on E15.5 or E18.5, and fetal brains were collected and analyzed for [(3)H]mitoxantrone (BCRP1-specific substrate) accumulation and Abcg2/BCRP1 expression. In another six groups (n = 4-5/group), pregnant mice were treated with DEX (0.1 or 1 mg/kg) or vehicle (saline) from either E9.5 to E15.5 (midgestation) or E12.5 to E18.5 (late gestation) and then injected with [(3)H]mitoxantrone. In conclusion, Abcg2 mRNA expression significantly decreases with advancing gestation, while BCRP1-mediated neuroprotection increases. Furthermore, there is a dose-, sex-, and age-dependent effect of DEX on Abcg2 mRNA in the fetal brain in vivo, indicating a complex regulatory role of glucocorticoid during development.

Effects of the isoflavonoid biochanin A on the transport of mitoxantrone in vitro and in vivo

The aim of our study was to investigate the effect of biochanin A on the accumulation and transport of mitoxantrone in breast cancer resistance protein (BCRP)-expressing normal cells and its impact on the pharmacokinetics (PK) and tissue distribution of mitoxantrone. In accumulation studies, the intracellular level of mitoxantrone was significantly increased in the presence of 2.5 or 25 microM of biochanin A in both murine and human BCRP-expressing Madin-Darby canine kidney (MDCK) cells, with no effect in corresponding MDCK/Mock cells. In bi-directional transport studies, the P(app,B-A) value of mitoxantrone with biochanin A co-treatment was much lower (6.66+/-0.84x10(-7) cm/s) than that in the absence of biochanin A (21.4+/-4.14x10(-7) cm/s), indicating inhibition of Bcrp1-mediated efflux. To evaluate whether our in vitro results might translate into an in vivo interaction, mitoxantrone PK and tissue distribution, with and without co-administration of biochanin A, was investigated. In contrast to our in vitro results, biochanin A (10 mg/kg, i.v.) had no impact on the concentration of mitoxantrone in plasma and most tissues collected (brain, heart, liver and lung). Surprisingly, the concentrations of mitoxantrone in spleen and kidney were even decreased when biochanin A was co-administered. Interestingly, it was found that the intracellular fluorescence of mitoxantrone was decreased 31.9% when co-incubated with 10 microM biochanin A in P-glycoprotein (P-gp) expressing MCF-7/ADR cells, indicating potential P-gp stimulation. The species difference of the inhibitory effect of biochanin A on BCRP, the extensive metabolism of biochanin A, as well as the stimulation effect of biochanin A on P-gp, may contribute to this in vitro-in vivo disconnect.