Phospholipids as multidrug resistance modulators of the transport of epirubicin in human intestinal epithelial Caco-2 cell layers and everted gut sacs of rats

Intratracheal Administration of Itraconazole-Loaded Hyaluronated Glycerosomes as a Promising Nanoplatform for the Treatment of Lung Cancer: Formulation, Physiochemical, and In Vivo Distribution

BACKGROUND

Itraconazole (ITZ) is an antiangiogenic agent recognized as a potent suppressor of endothelial cell growth that suppresses angiogenesis. Nevertheless, its exploitation is significantly restricted by its low bioavailability and systematic side effects. The objective of this study was to utilize glycerosomes (GLY), glycerol-developed vesicles, as innovative nanovesicles for successful ITZ pulmonary drug delivery.

METHODS

The glycerosomes were functionalized with hyaluronic acid (HA-GLY) to potentiate the anticancer efficacy of ITZ and extend its local bio-fate. ITZ-HA-GLY were fabricated using soybean phosphatidylcholine, tween 80, HA, and sonication time via a thin-film hydration approach according to a 24 full factorial design. The impact of formulation parameters on ITZ-HA-GLY physicochemical properties, as well as the optimal formulation option, was evaluated using Design-Expert®. Sulphorhodamine-B (SRB) colorimetric cytotoxicity assay of the optimized ITZ-HA-GLY versus ITZ suspension was explored in the human A549 cell line. The in vivo pharmacokinetics and bio-distribution examined subsequent to intratracheal administrations of ITZ suspension, and ITZ-HA-GLY were scrutinized in rats.

RESULTS

The optimized ITZ-HA-GLY unveiled vesicles of size 210.23 ± 6.43 nm, zeta potential of 41.06 ± 2.62 mV, and entrapment efficiency of 73.65 ± 1.76%. Additionally, ITZ-HA-GLY manifested a far lower IC50 of 13.03 ± 0.2 µg/mL on the A549 cell line than that of ITZ suspension (28.14 ± 1.6 µg/mL). Additionally, the biodistribution analysis revealed a higher concentration of ITZ-HA-GLY within the lung tissues by 3.64-fold as compared to ITZ suspension. Furthermore, the mean resistance time of ITZ-HA-GLY declined more slowly with 14 h as compared to ITZ suspension, confirming the accumulation of ITZ inside the lungs and their promising usage as a target for the treatment of lung disease.

CONCLUSIONS

These data indicate that the improved ITZ-HA-GLY demonstrates significant promise and represents an exciting prospect in intratracheal delivery systems for lung cancer treatment, meriting further investigation.

Liposome-Micelle-Hybrid (LMH) Carriers for Controlled Co-Delivery of 5-FU and Paclitaxel as Chemotherapeutics

Paclitaxel (PTX) and 5-fluorouracil (5-FU) are clinically relevant chemotherapeutics, but both suffer a range of biopharmaceutical challenges (e.g., either low solubility or permeability and limited controlled release from nanocarriers), which reduces their effectiveness in new medicines. Anticancer drugs have several major limitations, which include non-specificity, wide biological distribution, a short half-life, and systemic toxicity. Here, we investigate the potential of liposome-micelle-hybrid (LMH) carriers (i.e., drug-loaded micelles encapsulated within drug-loaded liposomes) to enhance the co-formulation and delivery of PTX and 5-FU, facilitating new delivery opportunities with enhanced chemotherapeutic performance. We focus on the combination of liposomes and micelles for co-delivery of PTX and 5_FU to investigate increased drug loading, improved solubility, and transport/permeability to enhance chemotherapeutic potential. Furthermore, combination chemotherapy (i.e., containing two or more drugs in a single formulation) may offer improved pharmacological performance. Compared with individual liposome and micelle formulations, the optimized PTX-5FU-LMH carriers demonstrated increased drug loading and solubility, temperature-sensitive release, enhanced permeability in a Caco-2 cell monolayer model, and cancer cell eradication. LMH has significant potential for cancer drug delivery and as a next-generation chemotherapeutic.

Self-nanoemulsifying Drug Delivery System: A Versatile Carrier for Lipophilic Drugs

BACKGROUND

Lipid-based systems such as self-nanoemulsifying drug delivery systems (SNEDDS) have resurged the eminence of nanoemulsions and offer many useful drug delivery opportunities. In the modern drug discovery era, there is a constant increase in the number of poorly soluble new chemical entities that suffer from poor and erratic bioavailability problems. The oral route possesses some major disadvantages, such as lack of constant drug levels in plasma, firstpass metabolism, which results in poor bioavailability. To address these problems, various lipidbased therapeutic systems are available from which self-enanoemulsifying systems have the potential to increase the bioavailability of poorly soluble drugs.

METHODS

SNEDDS is the isotropic mixture of oils, surfactant, and co-surfactant having droplet size in the range of 100-200 nm, which spontaneously emulsifies when it contacts with aqueous media in gastrointestinal (G.I) fluid. Various preparative methods are available for SNEDDS, such as high-pressure homogenizer, microfluidization, sonication, phase inversion, and shear state methods. These methods show favorable benefits in drug delivery. Self-nanoemulsifying drug delivery system possesses some disadvantages like precipitation of drug in G.I fluid or possible drug leaving in the capsule dosage form due to incompatibility issues, which can be overcome by more advanced techniques like supersaturated SNEDDS containing a precipitation inhibitor or Solid SNEDDS. These areformulated either through spray drying or using a solid carrier.

CONCLUSION

The lipid-based nanocarrier (SNEDDS) plays a significant role in drug delivery to overcome the poor solubility and oral bioavailability. This review highlights the elaborative aspects of the diverse advantages of SNEDDS based formulations.

Oral meropenem for superbugs: challenges and opportunities

An increase in the number of multidrug-resistant microbial strains is the biggest threat to global health and is projected to cause >10 million deaths by 2055. The carbapenem family of antibacterial drugs are an important class of last-resort treatment of infections caused by drug-resistant bacteria and are only available as an injectable formulation. Given their instability within the gut and poor permeability across the gut wall, oral carbapenem formulations show poor bioavailability. Meropenem (MER), a carbapenem antibiotic, has broad-spectrum antibacterial activity, but suffers from the above-mentioned issues. In this review, we discuss strategies for improving the oral bioavailability of MER, such as inhibiting tubular secretion, prodrug formulations, and use of nanomedicine. We also highlight challenges and emerging approaches for the development of oral MER.

A fluorescence study of the loading and time stability of doxorubicin in sodium cholate/PEO-PPO-PEO triblock copolymer mixed micelles

HYPOTHESIS

Doxorubicin hydrochloride (DX) is one of the most powerful anticancer agents though its clinical use is impaired by severe undesired side effects. DX encapsulation in nanocarrier systems has been introduced as a mean to reduce its toxicity. Micelles of the nonionic triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) (PEO-PPO-PEO), are very promising carrier systems. The positive charge of DX confines the drug to the hydrophilic corona region of the micelles. The use of mixed micelles of PEO-PPO-PEO copolymers and a negatively charged bile salt should favour the solubilization of DX in the apolar core region of the micelles.

EXPERIMENTS

We studied the DX uptake in the micellar systems formed by sodium cholate (NaC) and the PEO₁₀₀PPO₆₅PEO₁₀₀ (F127) copolymer, prepared with different mole ratios (MR = n_NaC/n_F127) in the range 0 ÷ 1. The systems were characterized by small angle X-ray scattering (SAXS) and dynamic light scattering (DLS); DX encapsulation was followed by steady-state and time-resolved fluorescence spectroscopy.

FINDINGS

The successful solubilization of DX in the host micellar systems did not affect their structure, as evidenced by both SAXS and DLS data. In the presence of NaC, DX experiences a more apolar environment as indicated by its characteristic fluorescent behaviour. The almost complete uptake of the drug occurred shortly after the sample preparation; however, time resolved fluorescence revealed a slow partition of DX between corona and core regions of the micelles. DX degradation in the mixed micellar systems was markedly reduced relative to aqueous DX solutions.

Hyaluronated imatinib liposomes with hybrid approach to target CD44 and P-gp overexpressing MDR cancer: an in-vitro, in-vivo and mechanistic investigation

Multi Drug Resistance (MDR) of cancer cells is a constant threat to the clinically used drugs as well as new drug development. In present work, we aimed to assess in-vitro as well as in-vivo efficacy of the developed Imatinib loaded liposomes in MDR cancer. An array of tests was also carried out to comprehensively understand the bio-mechanism that enable these nanocarriers to modulate P-gp activity. Hyaluronic acid coated, Imatinib mesylate containing lipsomes (HA-LIPO-IM) were analysed through in-vitro and in-vivo studies in MDR cancer cells and tumour models. Effect of developed hyaluronated liposomes on various biomolecular mechanisms was also evaluated. Around 3.5 times lower IC₅₀ for HA-LIPO-IM in comparison to drug solution in HT-29 and Colo-320 cells proved the enhanced action of the drug in MDR cells. HA-LIPO formulations were demonstrated to have inhibitory effect on ATPase enzyme. Molecular masking of Imatinib mesylate and CD-44 mediated endocytosis were also found responsible for anti-MDR effect. In-vivo studies revealed the prolonged tumour accumulation and 4-fold increase in tumour regression efficacy of HA-LIPO-IM in comparison to free drug solution. The work demonstrated the target specific accumulation of HA-LIPO-IM in CD-44 overexpressing cancer cells through P-gp modulation.

Monitoring Tumor Response after Liposomal Doxorubicin in Combination with Liposomal Vinorelbine Treatment Using 3'-Deoxy-3'-[18F]Fluorothymidine PET

PURPOSE

Surgical resection is the standard treatment for localized colorectal cancer, which is the most common type of gastrointestinal cancer. However, over 40 % cases are diagnosed metastasized and apparently inoperable. Systemic chemotherapy provides an alternative to these patients. This study aims to evaluate the therapeutic potential of liposomal doxorubicin (lipoDox) in combination with liposomal vinorelbine (lipoVNB) in a CT-26 colon carcinoma-bearing mouse model.

PROCEDURES

The in vitro cytotoxicity of Dox and VNB on CT-26 cancer cells was determined by MTT and colony formation assays. Mice were subcutaneously inoculated with 2 × 10⁵ of CT-26 cells in the right hind flank. When tumor size reached 200 ± 50 mm³, mice were assigned to receive different treatment protocols. The pharmacokinetics, micro single-photon emission computed tomography/x-ray computed tomography imaging, biodistribution, and immunohistochemical staining studies were performed to survey the therapeutic efficacy of each regimen.

RESULTS

Based on the results of pharmacokinetic study, co-administration of lipoDox and lipoVNB did not affect their individual systemic distribution, while lipoDox retained longer in blood than lipoVNB did. Superior tumor growth retardation was observed in the group received lipoDox plus lipoVNB administration (1 mg/kg each, namely D₁V₁) than those injected with lipoDox plus VNB (1 mg/kg each, namely D₁fV₁). No severe side effects were detected in each group. The tumor-to-muscle ratio (T/M) derived from 3'-dexoy-3'-[¹⁸F]fluorothymidine ([¹⁸F]FLT) micro positron emission tomography (PET) images of D₁V₁- and D₁fV₁-treated mice and the controls on day 7 was 6.88 ± 0.54, 7.50 ± 0.84, and 9.87 ± 0.73, respectively, suggesting that D₁V₁ is a more efficacious regimen against CT-26 xenografts. The results of proliferating cell nuclear antigen (PCNA) immunohistochemical staining were consistent with those findings obtained from [¹⁸F]FLT microPET imaging.

CONCLUSION

This study demonstrated that lipoDox in combination with lipoVNB was more efficacious than clinically used regimen, lipoDox plus VNB, in the treatment of colon carcinoma and [¹⁸F]FLT-PET is a promising approach in monitoring the treatment outcome at early stage.

Synthesis and cellular characterization of various nano-assemblies of cell penetrating peptide-epirubicin-polyglutamate conjugates for the enhancement of antitumor activity

A new class of cell penetrating peptides (CPPs) named peptide amphiphile was designed to improve the intracellular uptake and the antitumor activity of epirubicin (EPR). Various amphiphilic CPPs were synthesized by solid phase peptide synthesis method and were chemically conjugated to EPR. Their corresponding nanoparticles (CPPs-E4 and CPPs-E8) were prepared via non-covalent binding of the peptides and polyanions. Cytotoxicity and anti-proliferative activity were evaluated by MTT assay. Cellular uptake was examined by flow cytometry and fluorescence microscopy. The CPPs exhibited slight cytotoxicity. Binding of polyglutamate to CPPs (CPPs-E4 and CPPs-E8 nanoparticles) decreased their cytotoxicity. CPPs-E8 nanoparticles showed lower cytotoxicity than CPPs-E4 nanoparticles. Cellular uptake of K3W4K3-E8, K2W4K2-E8 and W3K4W3-E8 reached 100% with no difference between each of the mentioned CPPs and its nanoparticles at 50 µM. The anti-proliferative activity of EPR was enhanced following conjugation to peptides and nanoparticles at 25 µM. CPPs-EPR-E4 and CPPs-E8-EPR nanoparticles displayed higher anti-proliferative activity than CPPs-EPR at 25 µM. CPPs-E8-EPR nanoparticles showed higher anti-proliferative activity than CPPs-E4-EPR. K3W4K3-E8-EPR nanoparticles exhibited the highest anti-proliferative activity at 25 µM. The synthesized peptide nanoparticles are proposed as suitable carriers for improving the intracellular delivery of EPR into tumor cells with low cytotoxicity and high antitumor activity.

Evaluation of iron transport from ferrous glycinate liposomes using Caco-2 cell model

Background

Iron fortification of foods is currently a strategy employed to fight iron deficiency in countries. Liposomes were assumed to be a potential carrier of iron supplements.

Objective

The objective of this study was to investigate the iron transport from ferrous glycinate liposomes, and to estimate the effects of liposomal carriers, phytic acid, zinc and particle size on iron transport using Caco-2 cell models.

Methods

Caco-2 cells were cultured and seeded in DMEM medium. Minimum essential medium was added to the basolateral side. Iron liposome suspensions were added to the apical side of the transwell.

Results

The iron transport from ferrous glycinate liposomes was significantly higher than that from ferrous glycinate. In the presence of phytic acid or zinc ion, iron transport from ferrous glycinate liposomes and ferrous glycinate was evidently inhibited, and iron transport decreased with increasing phytic acid concentration. Iron transport was decreased with increase of particle size increasing of ferrous glycinate liposome.

Conclusion

Liposomes could behave as more than a simple carrier, and iron transport from liposomes could be implemented via a mechanism different from the regulated non-heme iron pathway.

MDR in cancer: Addressing the underlying cellular alterations with the use of nanocarriers

Multidrug resistance (MDR) is associated with a wide range of pathological changes at different cellular and intracellular levels. Nanoparticles (NPs) have been extensively exploited as the carriers of MDR reversing payloads to resistant tumor cells. However, when properly formulated in terms of chemical composition and physicochemical properties, NPs can serve as beyond delivery systems and help overcome MDR even without carrying a load of chemosensitizers or MDR reversing molecular cargos. Whether serving as drug carriers or beyond, a wise design of the nanoparticulate systems to overcome the cellular and intracellular alterations underlying the resistance is imperative. Within the current review, we will initially discuss the cellular changes occurring in resistant cells and how such changes lead to chemotherapy failure and cancer cell survival. We will then focus on different mechanisms through which nanosystems with appropriate chemical composition and physicochemical properties can serve as MDR reversing units at different cellular and intracellular levels according to the changes that underlie the resistance. Finally, we will conclude by discussing logical grounds for a wise and rational design of MDR reversing nanoparticulate systems to improve the cancer therapeutic approaches.

Effects of polyethylene glycols on intestinal efflux pump expression and activity in Caco-2 cells

The present study was planned to investigate the influence of polyethylene glycols (PEGs) on the activity and expression of P-glycoprotein (P-gp). Sub-toxic concentrations of PEGs in Caco-2 cells were determined using the MTT test assay. Then the measurement of Rhodamine-123 (Rho-123) uptake, a P-gp fluorescence substrate, in Caco-2 cells confronting PEG 400 (1% and 2% w/v), PEG 4000 (2% and 4% w/v), PEG 6000 (2% and 4% w/v), PEG 10000 (2% and 4% w/v), PEG 15000 (1% and 2% w/v), and PEG 35000 (2% and 4% w/v) overnight was taken to elucidate whether non-toxic concentrations of PEGs are able to impact P-gp activity. Furthermore, western blotting was carried out to investigate P-gp protein expression. The results showed that PEG 400 at concentrations of 1% (w/v) and 2% (w/v) and PEG 6000 at the concentration of 4% (w/v) are notably capable of blocking P-gp. Based on the obtained results it is concluded that the mentioned excipients could be used to obstruct P-gp efflux transporter in order to increase the bioavailability of co-administered substrate drug.

Styrene maleic acid micelles as a nanocarrier system for oral anticancer drug delivery - dual uptake through enterocytes and M-cells

Drug delivery systems could potentially overcome low bioavailability and gastrointestinal toxicity, which are the major challenges for the development of oral anticancer drugs. Herein, we demonstrate the ability of styrene maleic acid (SMA) nanomicelles encapsulating epirubicin to traverse in vitro and ex vivo models of the intestinal epithelium without affecting the tissue integrity. Further, SMA micelles encapsulating a fluorescent dye dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI) showed twofold higher accumulation in the liver and spleen, 15-fold higher accumulation in the tumor, and sixfold higher accumulation in the lung as compared with the free DiI, following oral administration in a mice xenograft breast cancer model. Additionally, SMA micelles showed colocalization with microfold (M)-cells and accumulation in Peyer’s patches, which together confirms the M-cell mediated uptake and transport of SMA micelles. Our results indicate that SMA micelles, showing dual uptake by enterocytes and M-cells, are a potential tool for safe oral anticancer drug delivery.

Regulation of BAX/BCL2 gene expression in breast cancer cells by docetaxel-loaded human serum albumin nanoparticles

Today, using nanoparticle-based drug delivery systems has expanded to avoid anticancer side effects. Taxanes are important chemotherapeutic agents in the treatment of metastatic breast cancer. In this study, docetaxel (DTX)-loaded human serum albumin (HSA) nanoparticles (NPs) were prepared and characterized. Drug toxicity of the nanoparticles was measured by MTT assay with different drug concentrations (0.01, 0.1, 0.5, 1 and 5 μM) at different incubation times (24, 48 and 72 h). Expression of BAX/BCL2 mRNA levels was determined by real-time PCR. The size of NPs prepared and used in our study was about 147 nm with surface charge of -29.6 mV. Results obtained from MTT assay showed that 0.5 μM of free drug had 50 % toxicity on MCF-7 cells after 48-h incubation. Real-time PCR results showed an increase in expression of BAX and no change for BCL2. In conclusion, a significant overexpression of BAX gene and changes in BAX/BCL2 ratio were observed for DTX-loaded HSA nanoparticles compared with free DTX and may provide a potential therapy to inhibit anticancer drug resistance.

Intestinal transport of sophocarpine across the Caco-2 cell monolayer model and quantification by LC/MS

Sophocarpine is a biologically active component obtained from the foxtail-like sophora herb and seed that is often orally administered for the treatment of cancer and chronic bronchial asthma. The aim of this study was to develop a rapid and specific LC/MS method for the determination of sophocarpine and to explore its transcellular transport mechanism across the Caco-2 (the human colon adenocarcia cell lines) monolayer cell transwell model. Caco-2 cells were seeded on permeable polycarbonate membranes and incubated for 21 days. Before the experiment, the trans-epithelial electric resistance, integrity and alkaline phosphatase activity of the Caco-2 monolayers were verified and used in subsequent experiments. In the Caco-2 model constructed, many influencing factors were investigated, including time, concentration, pH and different protein inhibitors. The results suggested that sophocarpine was transported mainly by passive diffusion. The flux of sophocarpine was time- and concentration-dependent, and the pH also had an effect on its transportation. The PappBA was higher than PappAB , indicating that a polarized transport might exist for sophocarpine. MK-571 and reserpine, inhibitors of the multidrug resistance associated protein 2 and the breast cancer resistance protein, decreased the efflux of sophocarpine, while verapamil had no effect on its transport. These results revealed that sophocarpine is absorbed mainly by passive diffusion, and that a carrier-mediated mechanism is also involved in the transport of sophocarpine.

Strategies for oral delivery and mitochondrial targeting of CoQ10

Coenzyme Q10 (CoQ10), also known as ubiquinone or ubidecarenone, is a powerful, endogenously produced, intracellularly existing lipophilic antioxidant. It combats reactive oxygen species (ROS) known to be responsible for a variety of human pathological conditions. Its target site is the inner mitochondrial membrane (IMM) of each cell. In case of deficiency and/or aging, CoQ10 oral supplementation is warranted. However, CoQ10 has low oral bioavailability due to its lipophilic nature, large molecular weight, regional differences in its gastrointestinal permeability and involvement of multitransporters. Intracellular delivery and mitochondrial target ability issues pose additional hurdles. To maximize CoQ10 delivery to its biopharmaceutical target, numerous approaches have been undertaken. The review summaries the current research on CoQ10 bioavailability and highlights the headways to obtain a satisfactory intracellular and targeted mitochondrial delivery. Unresolved questions and research gaps were identified to bring this promising natural product to the forefront of therapeutic agents for treatment of different pathologies.

Hyaluronan coated liposomes as the intravenous platform for delivery of imatinib mesylate in MDR colon cancer

Imatinib mesylate has been evaluated for possible potential in treatment of colon cancer in recent times. However, due to significant reporting of P-gp expression in colon cancer, it can come across set back due to MDR. Therefore, in present work the liposomal formulation containing imatinib-bile salt conjugate was developed and investigated for its comparative performance in MDR colon cancer cells and surface modified with hyaluronic acid for achieving low hemotoxicity with stealth characteristics. Imatinib was successfully conjugated with sodium-deoxycholate by charged conjugation and evaluated through FTIR, DSC and PXRD. The developed conjugate (IM-SD) was encapsulated in liposomes and the conditions were optimized by Box-Behnken statistical design to achieve a size of 56.56±1.23 nm along with 99.11±0.89% entrapment efficiency (LIPO). The liposomes were surface modified with hyaluronic acid and the size was enhanced to 159.14±3.2 nm (HA-LIPO). Flow cytometric studies demonstrated the enhanced uptake of P-gp substrate rhodamine dye in P-gp positive colo 320 colon cancer cells. In addition, an enhanced cellular internalization of HA-LIPO in CD-44 positive HT-29 and colo 320 cells indicates the targeting attributes of the hyaluronan coated liposomes. Finally, the hyaluronan coated liposomes were also found to have low opsonization activity.

Surface engineered nanostructured lipid carriers for targeting MDR tumor: Part I. Synthesis, characterization and in vitro investigation

Over expression of P-glycoprotein (P-gp) in cancer cells often results in highly aggressive, multi-drug resistant (MDR) phenotype. Such tumors are very difficult to treat with conventional therapy and often lead to failure of the treatment. In this work, we fabricated surface engineered hybrid lipid nanoparticles grafted with novel AL-HA polymer by mineralization technique. AL-HA graft polymer was prepared by covalent conjugation of alendronate sodium and hyaluronic acid. Compritol ATO 888 and capmule MCM C8 hybrid lipid mix was employed to prepare irinotecan containing nanostructured lipid carrier (NLC) by using functional excipients with P-gp inhibition activity. AL-HA was successfully grafted over NLC-Ir (uncoated irinotecan loaded NLC) by calcium-assisted mineralization. HA-NLC-Ir (hyaluronic acid coated irinotecan loaded NLC) particles have a nanoscale size of 386±2.2 nm along with a zeta potential value of 19.7±1.2 mV. NLC-Ir as well as HA-NLC-Ir showed a slow and sustained drug release. In vitro cell line studies performed on HT-29 and Colo-320 colon cancer cells revealed a reduced IC50 even in MDR cells. Flowcytometry studies demonstrated the capability of the developed nanocarriers to deliver the P-gp substrate moieties in MDR cancer cells. Furthermore, the targeting potential of HA-NLC was confirmed by CLSM studies. The cell line studies also revealed that NLC formulation had a potential of inhibiting P-gp by affecting ATPase activity and MDR1 gene expression.

Overview of the role of nanotechnological innovations in the detection and treatment of solid tumors

Nanotechnology, although still in its infantile stages, has the potential to revolutionize the diagnosis, treatment, and monitoring of disease progression and success of therapy for numerous diseases and conditions, not least of which is cancer. As it is a leading cause of mortality worldwide, early cancer detection, as well as safe and efficacious therapeutic intervention, will be indispensable in improving the prognosis related to cancers and overall survival rate, as well as health-related quality of life of patients diagnosed with cancer. The development of a relatively new field of nanomedicine, which combines various domains and technologies including nanotechnology, medicine, biology, pharmacology, mathematics, physics, and chemistry, has yielded different approaches to addressing these challenges. Of particular relevance in cancer, nanosystems have shown appreciable success in the realm of diagnosis and treatment. Characteristics attributable to these systems on account of the nanoscale size range allow for individualization of therapy, passive targeting, the attachment of targeting moieties for more specific targeting, minimally invasive procedures, and real-time imaging and monitoring of in vivo processes. Furthermore, incorporation into nanosystems may have the potential to reintroduce into clinical practice drugs that are no longer used because of various shortfalls, as well as aid in the registration of new, potent drugs with suboptimal pharmacokinetic profiles. Research into the development of nanosystems for cancer diagnosis and therapy is thus a rapidly emerging and viable field of study.

Strategies to address low drug solubility in discovery and development

Drugs with low water solubility are predisposed to low and variable oral bioavailability and, therefore, to variability in clinical response. Despite significant efforts to "design in" acceptable developability properties (including aqueous solubility) during lead optimization, approximately 40% of currently marketed compounds and most current drug development candidates remain poorly water-soluble. The fact that so many drug candidates of this type are advanced into development and clinical assessment is testament to an increasingly sophisticated understanding of the approaches that can be taken to promote apparent solubility in the gastrointestinal tract and to support drug exposure after oral administration. Here we provide a detailed commentary on the major challenges to the progression of a poorly water-soluble lead or development candidate and review the approaches and strategies that can be taken to facilitate compound progression. In particular, we address the fundamental principles that underpin the use of strategies, including pH adjustment and salt-form selection, polymorphs, cocrystals, cosolvents, surfactants, cyclodextrins, particle size reduction, amorphous solid dispersions, and lipid-based formulations. In each case, the theoretical basis for utility is described along with a detailed review of recent advances in the field. The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology (e.g., solid dispersions, lipid-based formulations, or salt forms) where required.

Inhibitory effect of phospholipids on P-glycoprotein: cellular studies in Caco-2, MDCKII mdr1 and MDCKII wildtype cells and P-gp ATPase activity measurements

Phospholipids are widely used excipients for pharmaceutical formulations, such as for preparing biphasic systems or to solubilize or encapsulate poorly soluble drugs. The present study investigates a new property of this class of substance: its ability to inhibit the efflux transporter Pglycoprotein (P-gp). P-gp is expressed in the intestinal epithelium, thereby significantly impairing the systemic absorption of various pharmaceutically active substances. The phospholipid screening performed in this study involved derivatives with different headgroups and fatty acid residues and a number of experimental parameters. For in vitro studies we carried out transport experiments and calcein accumulation assays in Caco-2- and MDCKII mdr1 and wildtype cell lines. The three compounds which displayed significant P-gp inhibition in both assays and in Caco-2 as well as in MDCKII mdr1, consisted of phosphatidylcholine (PC) and either two saturated fatty acid residues of eight (8:0 PC) or ten carbon atoms (10:0 PC), or of two unsaturated docosahexaeonic acid residues (cis-22:6 PC).Supported by P-gp ATPase activity measurements, 8:0 and 10:0 PC were assumed to function as direct P-gp inhibitors interacting with the transporter probably in their monomeric state, whereas a different, as yet unknown mechanism of action applied for cis-22:6 PC.Because of their proven ability to significantly inhibit P-gp in vitro, these phospholipids shall further be elucidated in vivo, whether they may truly serve to increase the bioavailability of orally applied drugs with a P-gp substrate character.

An epirubicin-conjugated nanocarrier with MRI function to overcome lethal multidrug-resistant bladder cancer

Multidrug resistance (MDR) presents a major obstacle to curing cancer. Chemotherapy failure can occur through both cell membrane drug resistance (CMDR) and nuclear drug resistance (NDR), and anticancer effectiveness of chemotherapeutic agents is especially reduced by their nuclear export. Here we report an exciting magnetically-targeted nanomedicine formed by conjugation of epirubicin (EPI) to non-toxic and high-magnetization nanocarrier (HMNC). Strikingly, HMNC-EPI overcomes both CMDR and NDR in human bladder cancer cell models, without using P-glycoprotein (P-gp) and nuclear pore inhibitors. Besides, the half-life of drug is prolonged ~1.8-fold (from 45 h to 81 h) at 37 °C, with a ~10-fold increase in concentration at the tumor site through magnetic targeting (MT). Moreover, malignant NDR bladder cancer can be effectively inhibited after 14 days in mice by just two injections and MT. We are the first to demonstrate the nanomedical strategy that can overcome the CMDR and NDR bladder cancers simultaneously, and proceed to the excellent MT therapy, significantly reducing the dosage and cardiotoxicity and holding great promise for incurable human MDR bladder cancer.

Methotrexate-loaded SLNs prepared by coacervation technique: in vitro cytotoxicity and in vivo pharmacokinetics and biodistribution

AIM

Recently, 'coacervation' has been proposed as a new method to prepare fatty acid solid lipid nanoparticles (SLNs). The aim of this work was to encapsulate methotrexate, a hydrophilic anticancer drug, within SLNs obtained by coacervation, through hydrophobic ion pairing and to evaluate the potential efficacy in in vitro and in vivo breast tumor models of drug-loaded nanoparticles.

MATERIALS & METHODS

Methotrexate-loaded SLN efficacy was evaluated in vitro towards MCF-7 and Mat B-III cell lines (human and murine breast tumor cell lines). Pharmacokinetics of drug-loaded nanoparticles was evaluated in male Wistar rats and biodistribution in a breast tumor model (Mat B-III) in female Fisher rats.

RESULTS

Drug-loaded SLNs showed an increased cytotoxicity towards MCF-7 and Mat B-III cell lines compared with free drug. After intravenous administration, drug plasmatic concentration was increased and a major drug accumulation within neoplastic tissue was shown when the drug was loaded in SLNs, compared with drug solution alone. Encapsulation of the drug within nanoparticles also increased its oral uptake after duodenal administration.

CONCLUSION

SLNs are promising vehicles for the delivery of methotrexate, since an increase of efficacy in vitro and a preferential accumulation in breast cancer in vivo were shown. Original submitted 29 October 2010; Revision submitted 19 March 2011.

Effects of tesmilifene, a substrate of CYP3A and an inhibitor of P-glycoprotein, on the pharmacokinetics of intravenous and oral docetaxel in rats

OBJECTIVES

It has been reported that docetaxel is a P-glycoprotein substrate and is metabolized via the cytochrome P450 (CYP) 3A subfamily in rats. Tesmilifene is a substrate of the CYP3A subfamily and is an inhibitor of P-glycoprotein. Thus, the effects of various doses of tesmilifene on the pharmacokinetics of intravenous and orally administered docetaxel have been investigated in rats.

METHODS

Docetaxel (20 mg/kg as base) was administered intravenously and orally without and with tesmilifene (5, 10, and 20 mg/kg) in rats.

KEY FINDINGS

After intravenous administration of docetaxel with tesmilifene, the values of nonrenal clearance (CL(NR)) and area under the plasma concentration-time (AUC) for docetaxel were comparable with those without tesmilifene. Tesmilifene did not increase the values of AUC or of absolute oral bioavailability (F) for docetaxel after oral administration of docetaxel with tesmilifene.

CONCLUSIONS

The inhibition for the metabolism of docetaxel via hepatic and intestinal CYP3A subfamily, and inhibition of P-glycoprotein-mediated efflux of docetaxel in the intestine by tesmilifene were almost negligible. The extremely low value of F for docetaxel was due to the incomplete absorption from the gastrointestinal tract and considerable first-pass metabolism of docetaxel in rats.

Effects of monensin liposomes on the cytotoxicity, apoptosis and expression of multidrug resistance genes in doxorubicin-resistant human breast tumour (MCF-7/dox) cell-line

We have evaluated the effects of monensin liposomes on drug resistance reversal, induction of apoptosis and expression of multidrug resistance (MDR) genes in a doxorubicin-resistant human breast tumour (MCF-7/dox) cell line. Monensin liposomes were prepared by the pH-gradient method. MCF-7/dox cells were treated with various anticancer drugs (doxorubicin, paclitaxel and etoposide) alone and in combination with monensin liposomes. The cytotoxicity was assessed using the crystal violet dye uptake method. The induction of apoptosis in MCF-7/dox cells was assessed by established techniques such as TUNEL (terminal deoxynucleotidyl transferase-mediated nick end labelling) staining and caspase-3 assay. The effect of monensin liposomes on doxorubicin accumulation in MCF-7/dox cells was monitored by fluorescent microscopy. Finally, the expression of MDR genes (MDR1 and MRP1) in MCF-7/dox cells following the exposure to doxorubicin alone and in combination with monensin liposomes was evaluated by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Our results indicated that monensin liposomes overcame drug resistance in MCF-7/dox cells to doxorubicin, etoposide and paclitaxel by 16.5-, 5.6- and 2.8-times, respectively. The combination of doxorubicin (2.5 μg mL−1) with monensin liposomes (20 times 10−8M) induced apoptosis in approximately 40% cells, whereas doxorubicin (2.5 μg mL−1) or monensin liposomes (20 times 10−8M) alone produced minimal apoptosis (<10%) in MCF-7/dox cells. Fluorescent microscopy revealed that monensin liposomes increased the accumulation of doxorubicin in MCF-7/dox cells. RT-PCR studies demonstrated that the expression of MDR1 and MRP1 was increased by 33 and 57%, respectively, in MCF-7/dox cells following treatment with doxorubicin (2.5 μg mL−1) for 72 h as compared with control MCF-7/dox cells. Furthermore, the levels of MDR1 and MRP1 in MCF-7/dox cells exposed to both doxorubicin and monensin liposomes showed a modest decrease as compared with MCF-7/dox cells treated with doxorubicin alone. In conclusion, the delivery of monensin via liposomes provided an opportunity to overcome drug resistance.

Quercetin and naringenin transport across human intestinal Caco-2 cells

Objectives

Flavonoids are phenolic compounds found in most edible fruits and vegetables. Previous studies have demonstrated their biological and beneficial effects on human health. However, their bioavailability and, in particular, their intestinal absorption mechanism have not yet been clearly identified. The aim of our work was to quantify and to characterize in vitro the nature of the transport of two flavonoids distinguished by their physicochemical and pharmacological properties: quercetin, a flavan-3-ol, and naringenin, a flavanone.

Methods

Differentiated and polarized Caco-2 human intestinal epithelial cell lines were used for this purpose.

Key findings

In our experimental conditions, quercetin and naringenin were poorly absorbed by Caco-2 cells. Quercetin was absorbed by passive diffusion and a pH-dependent mechanism mediated by the organic anion transporting protein B (OATP-B). It was not a multidrug resistance associated protein (MRP)1 substrate, but was substrate of the MRP2 efflux transporter and not P-glycoprotein (P-gp). Intestinal permeability from the apical to the basolateral side was higher for naringenin than for quercetin, which was partly explained by naringenin's physicochemical characteristics. Naringenin, partially absorbed by passive diffusion, was also an ATP-dependent transport substrate mediated by MRP1, but was not an OATP-B substrate. However, naringenin was secreted via active P-gp and MRP2 efflux transporters.

Conclusions

The contribution of ATP-dependent efflux transporters (MRP2 and P-gp) to the permeability of these compounds in the apical side could explain their low bioavailability. In conclusion, knowledge of the absorption mechanism of these two flavonoids was used to determine the intake level that has a beneficial effect on human health and their putative role in food—drug interactions.

Inhibition of carrier-mediated uptake of epirubicin reduces cytotoxicity in primary culture of rat hepatocytes

Epirubicin, an antineoplastic drug, is considered to be taken up by tumor cells via a common carrier by facilitated diffusion and is then pumped out in an energy-dependent manner because epirubicin is a substrate for P-glycoprotein (P-gp). However, this study investigated the details of the influx mechanism of epirubicin and demonstrated that epirubicin uptake was mediated by active carrier systems in addition to facilitated diffusion in the primary culture of rat hepatocytes. The uptake of epirubicin gradually increased in a saturated manner when the concentrations were between 1 x 10(-7) M and 1 x 10(-6) M. In contrast, the uptake increased progressively in a linear manner when the concentration was high (greater than 1 x 10(-6) M). The uptake of epirubicin at a clinical concentration (7.5 x 10(-7) M) was significantly reduced at 4 degrees C and significantly inhibited when pretreated with metabolic inhibitors (carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), rotenone and sodium azide) by nearly 25%. Furthermore, an organic anion transporter inhibitor, namely, 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS); organic anion transport substrates, namely, para-aminohippurate (PAH), taurocholic acid and estradiol 17-beta-D-glucuronide; and organic cation transporter inhibitors, namely, verapamil and tetraethylammonium significantly reduced the uptake of epirubicin. Furthermore, pretreatment with verapamil and PAH significantly prevented epirubicin-induced reduction of proliferative activity in rat hepatocytes. These results indicated that the uptake of epirubicin was induced, at least in part, by the active transport protein in rat hepatocytes; the inhibition of the probable transport protein protected the intact normal cells from the injury induced by the cytotoxicity of epirubicin.

A new polymer-lipid hybrid nanoparticle system increases cytotoxicity of doxorubicin against multidrug-resistant human breast cancer cells

PURPOSE

This work is intended to develop and evaluate a new polymer-lipid hybrid nanoparticle system that can efficiently load and release water-soluble anticancer drug doxorubicin hydrochloride (Dox) and enhance Dox toxicity against multidrug-resistant (MDR) cancer cells.

METHODS

Cationic Dox was complexed with a new soybean-oil-based anionic polymer and dispersed together with a lipid in water to form Dox-loaded solid lipid nanoparticles (Dox-SLNs). Drug loading and release properties were measured spectrophotometrically. The in vitro cytotoxicity of Dox-SLN and the excipients in an MDR human breast cancer cell line (MDA435/LCC6/MDR1) and its wild-type line were evaluated by trypan blue exclusion and clonogenic assays. Cellular uptake and retention of Dox were determined with a microplate fluorometer.

RESULTS

Dox-SLNs were prepared with a drug encapsulation efficiency of 60-80% and a particle size range of 80-350 nm. About 50% of the loaded drug was released in the first few hours and an additional 10-20% in 2 weeks. Treatment of the MDR cells with Dox-SLN resulted in over 8-fold increase in cell kill when compared to Dox solution treatment at equivalent doses. The blank SLN and the excipients exhibited little cytotoxicity. The biological activity of the released Dox remained unchanged from fresh, free Dox. Cellular Dox uptake and retention by the MDR cells were both significantly enhanced (p < 0.05) when Dox was delivered in Dox-SLN form.

CONCLUSIONS

The new polymer-lipid hybrid nanoparticle system is effective for delivery of Dox and enhances its efficacy against MDR breast cancer cells.

Influence of vitamin E TPGS poly(ethylene glycol) chain length on apical efflux transporters in Caco-2 cell monolayers

D-alpha-tocopheryl poly(ethylene glycol) 1000 succinate (TPGS 1000) is a widely used form of vitamin E. TPGS 1000 is comprised of a hydrophilic polar (water-soluble) head and a lipophilic (water-insoluble) alkyl tail. TPGS 1000 has been used as a solubilizer, an emulsifier and as a vehicle for lipid-based drug delivery formulations. Most recently, TPGS 1000 has been recognized as an effective oral absorption enhancer. An enhancing effect is consistent with a surfactant-induced inhibition of P-glycoprotein (P-gp), and perhaps other drug transporter proteins; however, the exact inhibition mechanism(s) remain unclear. Therefore, in an attempt to generate additional knowledge, we have synthesized and tested various TPGS analogs containing different PEG chain length (TPGS 200/238/400/600/1000/2000/3400/3500/4000/6000). These results demonstrate a relationship between TPGS PEG chain length and influence on rhodamine 123 (RHO) transport in Caco-2 monolayers, a relationship which may be illustrated using a Weibull distribution.

Clinical and pharmacokinetic phase II study of pegylated liposomal doxorubicin and vinorelbine in heavily pretreated recurrent ovarian carcinoma

BACKGROUND

This multicenter phase II study evaluated feasibility, clinical efficacy, toxicity and pharmacokinetics of the combination of pegylated liposomal doxorubicin (PLD) and vinorelbine (VNR) in patients with platinum-paclitaxel pretreated recurrent ovarian cancer.

PATIENTS AND METHODS

All patients received prior treatment with platinum and paclitaxel. Thirty-two heavily pretreated (median number of chemotherapy regimens two, range one to six) ovarian cancer patients received treatment with PLD 30 mg/m(2) and VNR 30 mg/m(2) every three weeks for six cycles. Ten patients entered the pharmacokinetic study, five receiving the PLD-VNR and five the VNR-PLD sequence.

RESULTS

In 30 patients evaluated for response and toxicity, the overall response rate was 37% and 10% of patients achieved stable disease. Median time to progression and overall survival were 5.5 months (range 1-10) and 9 months (range 2-16), respectively. Toxicity was generally mild and reversible. VNR AUC(tot) and plasma levels were considerably higher in the PLD-VNR sequence.

CONCLUSIONS

The PLD-VNR regimen exhibits significant activity in heavily pretreated patients, is well tolerated and is associated with encouraging survival. Preliminary pharmacokinetic results suggest the PLD-VNR sequence for further clinical applications. This regimen should be considered as a treatment option in patients with chemotherapy-resistant ovarian cancer.

Investigation of multidrug resistance in cultured human renal cell carcinoma cells by 31P-NMR spectroscopy and treatment survival assays

KTCTL-26 and KTCTL-2 are renal cell carcinoma (RCC) lines with high and low expression of P-170 glycoprotein, respectively. Inherent differences between the two cell lines in terms of phosphate metabolites and growth characteristics in culture were examined for possible association with multidrug resistance (MDR). Differences in response to drug treatment were investigated for 40 h incubations with various doses of vinblastine (VBL) alone or as cotreatments with various concentrations of the calcium antagonist diltiazem (DIL) and/or interferon-alpha (IFN-alpha). Treatment effects were quantitated using the MTT survival assay and 31P magnetic resonance spectroscopy (MRS) to determine phosphate metabolite profiles in intact cells. KTCTL-2 and KTCTL-26 cells exhibited significant inherent differences in phosphocholine, glycerophosphocholine, glycerophosphoethanolamine, and phosphocreatine levels. KTCTL-26 cells were more sensitive than KTCTL-2 to 0.011 mircroM VBL alone (87% vs. 102% survival) or to 0.011 microM BL + 10 microM DIL (55% vs. 80% survival). The latter treatment resulted in a significant decrease in the ratio of phosphocholine to glycerophosphocholine in KTCTL-26 cells but no significant changes in phosphate metabolites in KTCTL-2 cells. Metabolomic 31P MRS detects different metabolite profiles for RCC cell lines with different MDR phenotypes and may be useful for noninvasive characterization of tumors in a clinical setting.

Pegylated liposomal doxorubicin: Proof of principle using preclinical animal models and pharmacokinetic studies

Encapsulation of doxorubicin in polyethylene glycol-coated liposomes (Doxil/Caelyx [PLD]), was developed to enhance the safety and efficacy of conventional doxorubicin. The liposomes alter pharmacologic and pharmacokinetic parameters of conventional doxorubicin so that drug delivery to the tumor is enhanced while toxicity normally associated with conventional doxorubicin is decreased. In animals and humans, pharmacokinetic advantages of PLD include an increased area under the plasma concentration-time curve, longer distribution half-life, smaller volume of distribution, and reduced clearance. In preclinical models, PLD produced remission and cure against many cancers including tumors of the breast, lung, ovaries, prostate, colon, bladder, and pancreas, as well as lymphoma, sarcoma, and myeloma. It was also found to be effective as adjuvant therapy. In addition, it was found to cross the blood-brain barrier and induce remission in tumors of the central nervous system. Increased potency over conventional doxorubicin was observed and, in contrast to conventional doxorubicin, PLD was equally effective against low- and high-growth fraction tumors. The combination of PLD with vincristine or trastuzumab resulted in additive effects and possible synergy. PLD appeared to overcome multidrug resistance, possibly as the result of increased intracellular concentrations and an interaction between the liposome and P-glycoprotein function. On the basis of pharmacokinetic and preclinical studies, PLD, either alone or as part of combination therapy, has potential applications to treat a variety of cancers.

Liposome-based approaches to overcome anticancer drug resistance

Drug resistance remains an important obstacle towards better outcomes in the treatment of cancer. One general approach to overcome this problem has been to inhibit specific resistance mechanisms, such as P-glycoprotein (PGP)-mediated drug efflux, using small molecule agents or other therapeutic strategies. Alternatively, drug delivery approaches using liposomes or other carriers can in principle target drugs to tumor tissue, tumor cells, or even compartments within tumor cells. By increasing bioavailability of drugs at sites of action, these approaches may provide therapeutic advantages, including enhanced efficacy against resistant tumors. Current liposomal anthracyclines have achieved clinical use in cancer treatment by providing efficient encapsulation of drug in stable and non-reactive carriers, and there is evidence indicating potential benefit in some clinical settings involving resistant tumors. Other liposome-based strategies include constructs designed to be taken up by tumor cells, as well as further modifications to allow triggered drug release. These approaches seek to overcome drug resistance by more efficient delivery to tumor cells, and in some cases by concomitant avoidance or inhibition of drug efflux mechanisms. Newer agents employ molecular targeting, such as immunoliposomes using antibody-directed binding and internalization. These agents selectively deliver drug to tumor cells, can efficiently internalize for intracellular drug release, and can potentially enhance both efficacy and safety.

Population pharmacokinetics of liposomal daunorubicin in children

AIMS

To investigate the population pharmacokinetics of daunorubicin in children after administration of liposomal daunorubicin (Daunoxome).

METHODS

Plasma samples from 19 children with relapsed acute myeloic leukaemia and five children with other malignancies were collected. Daunoxome was administered as a 1- to 2.5 h infusion with doses ranging from 30 to 60 mg m(-2). Overall, 214 samples were analysed for daunorubicin using capillary electrophoresis, and population pharmacokinetic modelling was performed using NONMEM.

RESULTS

The data were best described by a one compartment model. Inclusion of interoccasion variability in the model (16.7% for clearance) improved strongly the precision of the estimates. The inclusion of body surface area or height as a covariate decreased interindividual variability. However, the best fit was obtained using the absolute dose, and when weight was included as a covariate for clearance (CL) and volume of distribution (V ). The final parameter estimates were: CL 6.41 ml h(-1) kg(-1) +/- 0.5 51% and V 65.4 ml kg(-1) +/- 0.5 27% (population mean +/- 0.5 interindividual variability). The area under the curve at a dose of 60 mg m(-2) was 231 mg l (-1)h.

CONCLUSIONS

In comparison with free daunorubicin, Daunoxome shows a low volume of distribution, a lower clearance and a lower interindividual variability in these parameters. This might be advantageous in reducing the variability in exposure to the drug.

Relationships between the hydrophilic-lipophilic balance values of pharmaceutical excipients and their multidrug resistance modulating effect in Caco-2 cells and rat intestines

The effects of a series of pharmaceutical excipients, including Span 80, Brij 30, Tween 20, Tween 80, Myrj 52, and sodium lauryl sulfate (with increasing hydrophilic-lipophilic balance (HLB) values) on the intracellular accumulation, transport kinetics, and intestinal absorption of epirubicin were investigated in both the human colon adenocarcinoma (Caco-2) cell line and the everted gut sacs of rat jejunum and ileum. The possible use of these excipients as multidrug resistance (MDR) reversing agents also was examined. Epirubicin uptake experiments using a flow cytometer showed that these selected excipients markedly enhanced the intracellular accumulation of epirubicin in Caco-2 cells in a dose-dependent manner. The optimal effect on the epirubicin uptake was characteristic of excipients with intermediate HLB values ranging from 10 to 17. Moreover, the optimal net efficacy was observed for excipients with polyoxyethylene chains and intermediate chain length of fatty acid and fatty alcohol (monolaurate for Tween 20, monooleate for Tween 80, monostearate for Myrj 52, and lauryl alcohol for Brij 30). These excipients significantly increased apical to basolateral absorption and substantially reduced basolateral to apical efflux of epirubicin across Caco-2 monolayers. Furthermore, the addition of Tween 20, Tween 80, Myrj 52, and Brij 30 markedly enhanced mucosal to serosal absorption of epirubicin in the rat jejunum and ileum. This study suggests that inhibition of intestinal P-glycoprotein (P-gp), multidrug resistance associated protein family (MRPs), or other transporter proteins by pharmaceutical excipients may improve oral absorption of drugs in MDR spectrum. The optimal HLB values of surfactant systems with suitable hydrocarbon chains and polar groups are an important factor in designing promising epirubicin formulations for reversing MDR. In conclusion, therapeutic efficacy of epirubicin may be enhanced by the use of such low toxicity excipients as absorption enhancers and MDR modulators in formulations. This provides a potential strategy for improving bioavailability in the optimization of formulations for drugs performing intestinal absorption and secretion.