In vitro moxifloxacin drug interaction with chemotherapeutics: implications for retinoblastoma management

Extrapolation of lung pharmacokinetics of antitubercular drugs from preclinical species to humans using PBPK modelling

OBJECTIVES

To develop physiologically based pharmacokinetic (PBPK) models for widely used anti-TB drugs, namely rifampicin, pyrazinamide, isoniazid, ethambutol and moxifloxacin lung pharmacokinetics (PK)-regarding both healthy and TB-infected tissue (cellular lesion and caseum)-in preclinical species and to extrapolate to humans.

METHODS

Empirical models were used for the plasma PK of each species, which were connected to multicompartment permeability-limited lung models within a middle-out PBPK approach with an appropriate physiological parameterization that was scalable across species. Lung's extracellular water (EW) was assumed to be the linking component between healthy and infected tissue, while passive diffusion was assumed for the drug transferring between cellular lesion and caseum.

RESULTS

In rabbits, optimized unbound fractions in intracellular water of rifampicin, moxifloxacin and ethambutol were 0.015, 0.056 and 0.08, respectively, while the optimized unbound fractions in EW of pyrazinamide and isoniazid in mice were 0.25 and 0.17, respectively. In humans, all mean extrapolated daily AUC and Cmax values of various lung regions were within 2-fold of the observed ones. Unbound concentrations in the caseum were lower than unbound plasma concentrations for both rifampicin and moxifloxacin. For rifampicin, unbound concentrations in cellular rim are slightly lower, while for moxifloxacin they are significantly higher than unbound plasma concentrations.

CONCLUSIONS

The developed PBPK approach was able to extrapolate lung PK from preclinical species to humans and to predict unbound concentrations in the various TB-infected regions, unlike empirical lung models. We found that plasma free drug PK is not always a good surrogate for TB-infected tissue unbound PK.

Effect of Dexketoprofen on the Disposition Kinetics of Moxifloxacin in Plasma and Lung in Male and Female Rats

BACKGROUND

The simultaneous use of NSAIDs and antibiotics is recommended for bacterial diseases in human and veterinary medicine. Moxifloxacin (MFX) and dexketoprofen (DEX) can be used simultaneously in bacterial infections. However, there are no studies on how the simultaneous use of DEX affects the pharmacokinetics of MFX in rats.

OBJECTIVES

The aim of this study was to determine the effect of DEX on plasma and lung pharmacokinetics of MFX in male and female rats.

METHODS

A total of 132 rats were randomly divided into 2 groups: MFX (n=66, 33 males/33 females) and MFX+DEX (n=66, 33 females/33 males). MFX at a dose of 20 mg/kg and DEX at a dose of 25 mg/kg were administered intraperitoneally. Plasma and lung concentrations of MFX were determined using the highperformance liquid chromatography-UV and pharmacokinetic parameters were evaluated by noncompartmental analysis.

RESULTS

Simultaneous administration of DEX increased the plasma and lung area under the curve from 0 to 8 h (AUC0-8) and peak concentration (Cmax) of MFX in rats, while it significantly decreased the total body clearance (CL/F). When female and male rats were compared, significant differences were detected in AUC0-8, Cmax, CL/F and volume of distribution. The AUC0-8lung/AUC0-8plasma ratios of MFX were calculated as 1.68 and 1.65 in female rats and 5.15 and 4.90 in male rats after single and combined use, respectively.

CONCLUSION

MFX was highly transferred to the lung tissue and this passage was remarkably higher in male rats. However, DEX administration increased the plasma concentration of MFX in both male and female rats but did not change its passage to the lung. However, there is a need for a more detailed investigation of the difference in the pharmacokinetics of MFX in male and female rats.

Anticancer activity and metabolic alteration in colon and prostate cancer cells by novel moxifloxacin conjugates with fatty acids

The positive and pro-economic trend in the management of cancer treatment is the search for the antineoplastic potential of known, widely used and safe drugs with a different clinical purpose. A good candidate seems to be moxifloxacin with broad-spectrum antibacterial activity, which as the member of the fourth generation fluoroquinolone is known to affect not only bacterial but also eukaryotic DNA topoisomerases, however at high concentration. Due to the fact that the modification of parent drug with lipid component can improve anticancer potential by increasing of bioavailability, selectivity, and cytotoxic efficiency, we evaluated the mechanisms of cytotoxic activity of novel moxifloxacin conjugates with fatty acids and verified metabolic profile in SW480, SW620 and PC3 cell lines. Our study revealed that cytotoxic potential of moxifloxacin conjugates was stronger than free moxifloxacin, moreover, they remained non-toxic to normal HaCaT cells. PC3 were more sensitive to MXF conjugates than colon cancer cells. The most promising cytotoxic activity exhibited conjugate 4m and 16m with oleic and stearic acid reducing viability of PC3 and SW620 cells. Tested conjugates activated caspases 3/7 and induced late-apoptosis, mainly in PC3 and SW620 cells. However, the most pronounced inhibition of NF-κB activation and IL-6 secretion was observed in SW480. Metabolomic analysis indicated influence of the moxifloxacin conjugates on intensity of lipid derivatives with the most successful metabolite profile in PC3. Our findings suggested the cytotoxic potential of moxifloxacin conjugates, especially with oleic and stearic acid can be beneficial in oncological therapy, including their possible anti-inflammatory and known antibacterial effect.

Fabrication of moxifloxacin HCl-loaded biodegradable chitosan nanoparticles for potential antibacterial and accelerated cutaneous wound healing efficacy

AIM

This work aims to formulate topical hybrid gel containing chitosan-coated moxifloxacin (MXF) HCl nanoparticles (NPs) with enhanced antibacterial and healing activity.

METHODS

MXF HCl NPs prepared by the ionic gelation method were loaded onto a hybrid chitosan carbomer gel. Size analysis of the prepared NPs was performed using SEM and Zeta-sizer. Further characterisation was done using Fourier transforms infra-red spectroscopy (FTIR), X-ray diffraction (XRD), and Thermogravimetric analysis (TGA). Prepared gel was evaluated for its in vitro drug release, biocompatibility, antibacterial activity, and stability studies under storage conditions. In-vivo wound healing was measured by observing percentage reduction in wound.

RESULTS

NPs have 359 ± 79 nm mean particle size, 31.01 mV zeta potential with 0.008 polydispersity index (PD1), 63.5% drug entrapment and 83 ± 3.5% drug release at pH 5.5. Hybrid chitosan carbomer gel showed good biocompatibility, antibacterial, in-vivo wound healing properties and stable properties.

CONCLUSIONS

NP-loaded hybrid gel can be an effective treatment for acute and challenged topical wounds.

Prediction of Moxifloxacin Concentrations in Tuberculosis Patient Populations by Physiologically Based Pharmacokinetic Modeling

Moxifloxacin has an important role in the treatment of tuberculosis (TB). Unfortunately, coadministration with the cornerstone TB drug rifampicin results in suboptimal plasma exposure. We aimed to gain insight into the moxifloxacin pharmacokinetics and the interaction with rifampicin. Moreover, we provided a mechanistic framework to understand moxifloxacin pharmacokinetics. We developed a physiologically based pharmacokinetic model in Simcyp version 19, with available and newly generated in vitro and in vivo data, to estimate pharmacokinetic parameters of moxifloxacin alone and when administered with rifampicin. By combining these strategies, we illustrate that the role of P-glycoprotein in moxifloxacin transport is limited and implicate MRP2 as transporter of moxifloxacin-glucuronide followed by rapid hydrolysis in the gut. Simulations of multiple dose area under the plasma concentration-time curve (AUC) of moxifloxacin (400 mg once daily) with and without rifampicin (600 mg once daily) were in accordance with clinically observed data (predicted/observed [P/O] ratio of 0.87 and 0.80, respectively). Importantly, increasing the moxifloxacin dose to 600 mg restored the plasma exposure both in actual patients with TB as well as in our simulations. Furthermore, we extrapolated the single dose model to pediatric populations (P/O AUC ratios, 1.04-1.52) and the multiple dose model to children with TB (P/O AUC ratio, 1.51). In conclusion, our combined approach resulted in new insights into moxifloxacin pharmacokinetics and accurate simulations of moxifloxacin exposure with and without rifampicin. Finally, various knowledge gaps were identified, which may be considered as avenues for further physiologically based pharmacokinetic refinement.

Drug Repurposing for Retinoblastoma: Recent Advances

Retinoblastoma is the intraocular malignancy that occurs during early childhood. The current standard of care includes chemotherapy followed by focal consolidative therapies, and enucleation. Unfortunately, these are associated with many side and late effects. New drugs and/or drug combinations need to be developed for safe and effective treatment. This compelling need stimulated efforts to explore drug repurposing for retinoblastoma. While conventional drug development is a lengthy and expensive process, drug repurposing is a faster, alternate approach, where an existing drug, not meant for treating cancer, can be repurposed to treat retinoblastoma. The present article reviews various attempts to test drugs approved for different purposes such as calcium channels blockers, non-steroidal antiinflammatory drugs, cardenolides, antidiabetic, antibiotics and antimalarial for treating retinoblastoma. It also discusses other promising candidates that could be explored for repurposing for retinoblastoma.

GSH depletion, mitochondrial membrane breakdown, caspase-3/7 activation and DNA fragmentation in U87MG glioblastoma cells: New insight into the mechanism of cytotoxicity induced by fluoroquinolones

Fluoroquinolones are a known synthetic group of antibiotics that have been the subject of many research interests. This class of antibiotics was shown to be cytotoxic towards various cancer cell lines, thus representing a potentially important source of new anticancer agents. The present study was designed to examine the effect of ciprofloxacin and moxifloxacin on cell viability, redox balance and apoptosis in U87MG glioblastoma cells. Herein, we found that both fluoroquinolones decrease the viability and exert an anti-proliferative effect on U87MG cells. The EC₅₀ values were found to be as 0.75 µmol/ml, 0.57 µmol/ml, 0.53 µmol/ml for ciprofloxacin and 24, 48, 72 h incubation time, respectively, and 0.48 µmol/ml, 0.22 µmol/ml, 0.15 µmol/ml for moxifloxacin and 24, 48, 72 h incubation time, respectively. Ciprofloxacin and moxifloxacin have also induced the intracellular GSH depletion and apoptosis as shown by externalization of phosphatidylserine, caspase-3/7 activation, S and sub-G₁ cell cycle arrest, nuclear morphological changes induction and DNA fragmentation. The mechanism of apoptosis was related to the loss of mitochondrial membrane potential suggesting activation of the intrinsic mitochondrial pathway. This is the first study that may provide the basis for understanding potential cellular and molecular mechanism underlying ciprofloxacin and moxifloxacin cytotoxic and pro-apoptotic effect towards U87MG glioblastoma cells, suggesting that these fluoroquinolone derivatives may have value for the development as anti-glioma agents.

Expression of multidrug resistance proteins in retinoblastoma

AIM

To elucidate the mechanism of multidrug resistance in retinoblastoma, and to acquire more insights into in vivo drug resistance.

METHODS

Three anticancer drug resistant Y79 human RB cells were generated against vincristine, etoposide or carboplatin, which are used for conventional chemotherapy in RB. Primary cultures from enucleated eyes after chemotherapy (PCNC) were also prepared. Their chemosensitivity to chemotherapeutic agents (vincristine, etoposide and carboplatin) were measured using MTT assay. Western blot analysis was performed to evaluate the expression of p53, Bcl-2 and various multidrug resistant proteins in retinoblastoma cells.

RESULTS

Following exposure to chemotherapeutic drugs, PCNC showed less sensitivity to drugs. No significant changes observed in the p53 expression, whereas Bcl-2 expression was found to be increased in the drug resistant cells as well as in PCNC. Increased expression of P-glycoprotein (P-gp) was observed in drug resistant Y79 cells; however there was no significant change in the expression of P-gp found between primary cultures of primarily enucleated eyes and PCNC. Multidrug resistance protein 1 (Mrp-1) expression was found to be elevated in the drug resistant Y79 cells as well as in PCNC. No significant change in the expression of lung resistance associated protein (Lrp) was observed in the drug resistant Y79 cells as well as in PCNC.

CONCLUSION

Our results suggest that multidrug resistant proteins are intrinsically present in retinoblastoma which causes treatment failure in managing retinoblastoma with chemotherapy.

Prenatal versus Postnatal Screening for Familial Retinoblastoma

PURPOSE

To compare overall outcomes of conventional postnatal screening of familial retinoblastoma and prenatal RB1 mutation identification followed by planned early-term delivery.

DESIGN

Retrospective, observational study.

PARTICIPANTS

Twenty children with familial retinoblastoma born between 1996 and 2014 and examined within 1 week of birth.

METHODS

Cohort 1 included spontaneously delivered neonates examined within 1 week of birth and confirmed postnatal to carry their family's RB1 mutant allele. Cohort 2 included infants identified by amniocentesis to carry their family's RB1 mutant allele, and therefore scheduled for early-term delivery (36-38 weeks' gestation). Treatment for retinoblastoma was performed at the Hospital for Sick Children, Toronto, Canada.

MAIN OUTCOME MEASURES

Age at first tumor in each eye, eye stage, treatments given, ocular salvage, treatment success (defined as avoidance of enucleation, external-beam irradiation, or both), visual outcome, number of anesthetics, pregnancy or delivery complications, and estimated treatment burden.

RESULTS

Vision-threatening tumors were present at birth in 4 of 8 infants in cohort 1 and in 3 of 12 infants in cohort 2. Eventually, all infants demonstrated tumors in both eyes. At the first treatment, 1 of 8 infants in cohort 1 had eyes in stage cT1a/cT1a or cT1a/cT0 (smallest and least vision-threatening tumors), compared with 8 of 12 infants in cohort 2 (P = 0.02). Null RB1 germline alleles induced earlier tumors than low-penetrance alleles (P = 0.03). Treatment success was achieved in 3 of 8 children in cohort 1 compared with 11 of 12 children in cohort 2 (P = 0.002). Acceptable vision (better than 0.2 decimal) was achieved for 8 of 16 eyes in cohort 1 compared with 21 of 24 eyes in cohort 2 (P = 0.014). Useful vision (better than 0.1, legal blindness) was achieved for 8 of 9 children in cohort 1 compared with 12 of 12 children in cohort 2. There were no complications related to early-term delivery. Median follow-up was 5.6 years, cohort 1 and 5.8 years, cohort 2.

CONCLUSIONS

When a parent had retinoblastoma, prenatal molecular diagnosis with early-term delivery increased the likelihood of infants born with no detectable tumors, better vision outcomes, and less invasive therapy. Prenatal molecular diagnosis facilitates anticipatory planning for both the child and family.

Update on Ophthalmic Oncology 2014: Retinoblastoma and Uveal Melanoma

PURPOSE

The aim of this study was to review peer-reviewed articles on ophthalmic oncology (specifically retinoblastoma and uveal melanoma) published from January to December 2014.

DESIGN

This study is a literature review.

METHODS

The terms retinoblastoma and uveal melanoma were used in a MEDLINE literature search. Abstracts were studied, and the most relevant articles were selected for inclusion and further in-depth review.

RESULTS

In retinoblastoma, more eyes are being salvaged due to intravitreal melphalan. The year 2014 marks a deepening in our understanding of the biological basis of the disease and the cell of origin. Knowledge on the genetic underpinnings of uveal melanoma has broadened to include other pathways, interactions, and potential therapeutic targets.

CONCLUSIONS

In 2014, there were valuable advancements in our knowledge of retinoblastoma and uveal melanoma. Some of these resulted in improved patient management.

Drug-drug interactions between moxifloxacin and rifampicin based on pharmacokinetics in vivo in rats

Moxifloxacin and rifampicin are all the first-line options for the treatment of active tuberculosis, which are often combined for the treatment of multidrug resistance pulmonary tuberculosis in clinic. However, the potential drug-drug interactions between moxifloxacin and rifampicin were unknown. The aim of this study was to investigate the drug-drug interactions between moxifloxacin and rifampicin based on their pharmacokinetics in vivo after oral administration of the single drug and both drugs, and reveal their mutual effects on their pharmacokinetics. Eighteen male Sprague-Dawley rats were randomly assigned to three groups: moxifloxacin group, rifampicin group and moxifloxacin + rifampicin group. Plasma concentrations of moxifloxacin and rifampicin were determined using LC-MS at the designated time points after drug administration, and the main pharmacokinetic parameters were calculated. In addition, effects of moxifloxacin and rifampicin on their metabolic rate and absorption were investigated using rat liver microsome incubation systems and Caco-2 cell transwell model. The main pharmacokinetic parameters of moxifloxacin including Tmax , Cmax , t1/2 and AUC(0-t) increased more in the moxifloxacin + rifampicin group than in the moxifloxacin group, but the difference was not significant (p > 0.05). However, the pharmacokinetic parameters of rifampicin, including peak concentration, area under the concentration-time curve, half-life and the area under the first moment plasma concentration-time curve, increased significantly (p < 0.05) compared with the rifampicin group, and the time to peak concentration decreased significantly (p < 0.05). The mean residence time of rifampicin also increased in moxifloxacin + rifampicin group compared with the rifampicin group, but the difference was not significant (p > 0.05). The rat liver microsome incubation experiment indicated that moxifloxacin could increase the metabolic rate of rifampicin from 23.7 to 38.7 min. However, the Caco-2 cell transwell experiment showed that moxifloxacin could not affect the absorption rate of rifampicin. These changes could enhance the drug efficacy, but they could also cause drug accumulation, which might induce adverse effect, so it was suggested that the drug dosage should be adjusted and the drug concentration in plasma should be monitored if moxifloxacin and rifampicin are co-administered. Copyright © 2016 John Wiley & Sons, Ltd.

Quinoline-Based Compound BPIQ Exerts Anti-Proliferative Effects on Human Retinoblastoma Cells via Modulating Intracellular Reactive Oxygen Species

Retinoblastoma (Rb) is the most common primary intraocular malignant tumor of childhood. It is important to develop the strategy for Rb treatment. We have tested a quinolone derivative 2,9-bis[2-(pyrrolidin-1-yl)ethoxy]-6-{4-[2-(pyrrolidin-1-yl)ethoxy]phenyl}-11H-indeno[1,2-c]quinolin-11-one (BPIQ) for its anti-cancer effects against Rb via cultured human Rb cell line Y79. Our results showed that BPIQ significantly inhibits cell growth of Y79. Furthermore, the flow cytometer-based assays and Western blotting showed that BPIQ induces the apoptosis of Y79 via increasing the level of reactive oxygen species (ROS). Besides, the activation of γH2AX, a DNA damage sensor in human Y79 cells was also observed, indicating the potential of BPIQ for causing DNA damage of Rb cells. On the contrary, BPIQ-induced apoptosis of Y79 cells was attenuated significantly by N-acetyl-L-cysteine (NAC), an ROS scavenger. The results of Western blot showed that BPIQ down-regulates the levels of anti-apoptotic proteins Bcl-2, survivin and XIAP while up-regulates the pro-apoptotic proteins Bad, Bax and Bid. Our present study demonstrated the anti-proliferative effect of BPIQ in human Y79 cells. The inhibitory effect of BPIQ on the proliferation of Y79 cells is, at least, partly mediated by the regulation of ROS and DNA damage pathway. In conclusion, BPIQ may provide an alternative option in the chemotherapeutics or chemoprevention on the Rb therapy in the future.