Genistein-loaded poloxamer 403/407 mixed micelles: preparation and pharmacokinetic study in rats

In the present study, we aimed to prepare poloxamer 403/407 mixed micelles in order to improve the solubility and oral bioavailability of genistein.Genistein was incorporated in the mixed poloxamer micelles by thin-film hydration method, and its physicochemical properties, including particle size, zeta potential, entrapment efficiency and drug loading, were investigated.In vitro release of genistein from the mixed micelles was monitored by dialysis method, and pharmacokinetic study of genistein loaded mixed micelles was carried out in rats. We found that the particle size and zeta potential of mixed micelles were (20.31±0.43) nm and (–8.94±0.35) mV, with encapsulation efficiency 90.59%±0.67% and drug loading 7.74%±0.05%. Solubility of genistein in mixed micelles reached 3.80 mg/mL, which was about 130 times higher than that in water.Genistein-loaded mixed micelles showed sustained release characteristics in vitro with no burst release phenomenon, but it was faster than suspension.The AUC_0–t andAUC_0–∞ of mixed micelles were 196.74% and 204.62% greater than that of genisein suspension, respectively.Consequently,poloxamer 403/407 mixed micelles significantly improved the solubility and oral bioavailability of genistein, which could be used as an effective drug delivery system for oral administration of poorly soluble drugs.     

Reverse micelle-loaded lipid nanocarriers: A novel drug delivery system for the sustained release of doxorubicin hydrochloride

In this study, we are pioneering new nanotechnology for the encapsulation of anticancer drugs (doxorubicin (DOX) and/or docetaxel (DOCE)), whatever their solubility and water affinity. The purpose of this study is to highlight the potential of this recently patented technology, by carrying out a thorough physicochemical characterisation of these multiscaled nanocarriers, followed by the study of an encapsulation and release model of hydrophilic anticancer drug. The formulation process is based on a low-energy nano-emulsification method and allows the generation of a structure composed of oil-based nanocarriers loaded with reverse micelles. Thanks to this, hydrophilic contents can be solubilised in the oily core of this kind of nano-emulsion along with lipophilic content. The results emphasise some original structure particularities due to the multistep formulation process, and the diffusion-based behaviour revealed for the DOX release profile that is shown to be intimately linked to the morphology of the particles.     

Antiangiogenic Effect of Docetaxel and Everolimus as Individual and Dual-Drug-Loaded Micellar Nanocarriers

Purpose

The in vitro inhibitory effect of Docetaxel (DTX) and Everolimus (EVR) alone and together in poly(ethylene glycol)-block-poly(D,L-lactic acid) (PEG-b-PLA) nanocarriers on angiogenic processes and acute toxicity in mice was evaluated.

Methods

PEG-b-PLA DTX and/or EVR nanocarriers were characterized for size, drug loading, stability, and drug release. Cell proliferation, tubule formation, and migration studies were performed in Human Umbilical Vein Endothelial Cells (HUVEC) and Maximum Tolerated Doses (MTD) studies were in mice.

Results

DTX and EVR loading was 1.93 and 2.00 mg/mL respectively with similar solubilities for dual-drug micelles. All micelles were below 30 nm with diffusion controlled drug release. The IC₅₀ for DTX, EVR micelles were, 6.80?±?0.67, 18.57?±?2.86 and 0.65?±?0.11 nM respectively with a synergistic inhibitory effect for dual-drug nanocarriers. Significant inhibition of tube formation occurred upon treatment with dual-drug nanocarriers as compared to individual micelles. EVR presence in dual-drug nanocarriers was able to significantly increase the inhibition of the migration of HUVEC by DTX. The MTDs for EVR, DTX and dual-drug micelles were 50, 30 and 20 mg/kg for each respectively.

Conclusions

DTX-EVR dual-drug nanocarriers have antiangiogenic effects in vitro mediated through cellular angiogenic process and possess clinically relevant MTD.     

Construction and application of biotin–poloxamer conjugate micelles for chemotherapeutics

Biotin was conjugated on poloxamer to prepare biotin–poloxamer (BP) conjugate micelles for chemotherapeutics. Epirubicin (EPI) was encapsulated in BP micelles. The EPI-loaded BP micelles were characterized in terms of size, ζ-potential, morphology, drug loading, drug encapsulation and drug release. Marrow leukemic HL-60 cells were used for evaluating the in vitro cytotoxicity of EPI-loaded BP micelles. Nude mice were axillainoculated subcutaneously HL-60 cells to establish tumour model for investigating the inhibition effects of EPI-loaded BP micelles. From the results, the sizes of these nanoparticles were about 100?nm. Fluorescence microscope observation supported the enhanced cellular uptake of the micelles. The order of the inhibition on tumour volume growth was: EPI-loaded BP micelles >EPI-loaded MATP micelles >EPI-loaded poloxamer micelles >EPI. BP micelles showed significant antitumour activity and low toxicity, compared with the non-targeted micelles. With the advantage of EPR effect and tumour-targeting potential, BP conjugate micelles might be developed as a new system for chemotherapeutics.     

Solubilized delivery of paliperidone palmitate by d-alpha-tocopheryl polyethylene glycol 1000 succinate micelles for improved short-term psychotic management

The objective of this work was to formulate paliperidone palmitate-loaded d-alpha-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS or TPGS) micelles for improved antipsychotic effect during short-term management of psychotic disorders. Vitamin E TPGS micelles containing paliperidone palmitate were prepared by the solvent casting method and control paliperidone palmitate formulations were prepared by simple sonication method. The prepared micelles and control paliperidone palmitate formulations were evaluated for different parameters. Particle sizes of prepared micelles, control paliperidone palmitate formulations were determined at 25?°C by dynamic light scattering technique and external surface morphology was determined by transmission electron microscopy analysis. The encapsulation efficiency was determined by spectrophotometery. In-vitro release studies of micelles and control formulations were carried out by dialysis bag diffusion method. The particle sizes of the paliperidone palmitate-loaded TPGS micelles were 26.5?nm. About 92% of drug encapsulation efficiency was achieved with micelles. The drug release from paliperidone palmitate-loaded TPGS micelles was sustained for more than 24?h with 40% of drug release. The TPGS product, i.e. paliperidone palmitate-loaded micelles, resulted in nano-sized delivery, solubility enhancement and permeability of the micelles which provided an improved and prolonged anti-psychotic effect in comparison to control paliperidone palmitate formulation.     

姜黄素聚合物胶束的制备及抗肿瘤活性评价

目的:制备姜黄素的维生素E聚乙二醇琥珀酸酯(TPGS)聚合物胶束,从而改善姜黄素的水溶性和抗肿瘤活性。方法:以TPGS为载体材料,采用薄膜水化法制备姜黄素胶束;以包封率和粒径为指标,考察水化温度、水化时间、药载比和水化体积的影响;以包封率、粒径、载药量为指标,经四因素三水平正交试验,确定姜黄素/TPGS胶束的最佳制备工艺;考察姜黄素/TPGS胶束的体外释放度;利用MTT法测试姜黄素/TPGS的体外抗肿瘤活性。结果:姜黄素/TPGS胶束的最佳药载比为1∶40,水化温度为60℃,水化时间为30 min,水化体积为6 mL;所得胶束平均粒径为11.02 nm, Zeta电位为-11.31,载药量为2.65%,包封率为96.20%;姜黄素/TPGS 48 h体外累积释放率为78%,具有一定的缓释性;MTT法表明,姜黄素/TPGS具有良好的抗肿瘤活性。结论:该文采用薄膜水化法制备了一种稳定的姜黄素/TPGS胶束,改善了姜黄素的水溶性,明显提高了其抗肿瘤效果。     

Enhanced rectal bioavailability of ibuprofen in rats by poloxamer 188 and menthol

To improve the bioavailability of poorly water-soluble ibuprofen in the rectum with poloxamer and menthol, the effects of menthol and poloxamer 188 on the aqueous solubility of ibuprofen were investigated. The dissolution and pharmacokinetic study of ibuprofen delivered by the poloxamer gels composed of poloxamer 188 and menthol were then performed. In the absence of poloxamer, the solubility of ibuprofen increased until the ratio of menthol to ibuprofen increased from 0:10 to 4:6 followed by an abrupt decrease in solubility above the ratio of 4:6, indicating that four parts menthol formed eutectic mixture with six parts ibuprofen. In the presence of poloxamer, the solutions with the same ratio of menthol to ibuprofen showed abrupt increase in the solubility of ibuprofen. The poloxamer gel with menthol/ibuprofen ratio of 1:9 and higher than 15% poloxamer 188 showed the maximum solubility of ibuprofen, 1.2mg/ml. Menthol improved the dissolution rates of ibuprofen from poloxamer gels. Release mechanism showed that the release rate of ibuprofen from the poloxamer gels without menthol was independent of the time but the drug might be released from the poloxamer gels with menthol by Fickian diffusion. Furthermore, the poloxamer gel with menthol (poloxamer/menthol/ibuprofen (15%/0.25%/2.5%)) gave significantly higher initial plasma concentrations, C(max) and AUC of ibuprofen than did solid suppository, indicating that the drug from poloxamer gel could be more absorbed than that from solid one in rats. Thus, the poloxamer gel with poloxamer 188 and menthol was a more effective rectal dosage form for ibuprofen.     

Development of novel ibuprofen-loaded solid dispersion with improved bioavailability using aqueous solution

To develop a novel ibuprofen-loaded solid dispersion with enhanced bioavailability, various ibuprofen-loaded solid dispersions were prepared with water, HPMC and poloxamer. The effect of HPMC and poloxamer on aqueous solubility of ibuprofen was investigated. The dissolution and bioavailability of solid dispersion in rats were then evaluated compared to ibuprofen powder. When the amount of carrier increased with a decreased in HPMC/poloxamer ratio, the aqueous solubility of ibuprofen was elevated. The solid dispersion composed of ibuprofen/HPMC/poloxamer at the weight ratio of 10:3:2 improved the drug solubility approximately 4 fold. It gave significantly higher initial plasma concentration, AUC and Cmax of drug than did ibuprofen powder in rats. The solid dispersion improved the bioavailability of drug about 4-fold compared to ibuprofen powder. Thus, this ibuprofen-loaded solid dispersion with water, HPMC and poloxamer was a more effective oral dosage form for improving the bioavailability of poor water-soluble ibuprofen.     

Improved solubility and in vitro dissolution of Ibuprofen from poloxamer gel using eutectic mixture with menthol

To improve the solubility and in vitro dissolution of poorly water-soluble ibuprofen with poloxamer and menthol, the effects of menthol and poloxamer 188 on the aqueous solubility of ibuprofen were investigated. The dissolution study of ibuprofen delivered by poloxamer gels composed of poloxamer 188 and menthol were performed. In the absence of poloxamer, the solubility of ibuprofen increased until the ratio of menthol to ibuprofen increased from 0:10 to 4:6, followed by an abrupt decrease in solubility above the ratio of 4:6, indicating that 4 parts of ibuprofen formed eutectic mixture with 6 parts of menthol. In the presence of poloxamer 188, the solutions with the same ratio of menthol to ibuprofen showed abrupt increase in the solubility of ibuprofen. Furthermore, the solution with ratio of 4:6 showed more than 2.5- and 6-fold increase in the solubility of ibuprofen compared with that without poloxamer and that without menthol, respectively. The poloxamer gel with menthol/ibuprofen ratio of 1:9 and higher than 15% poloxamer 188 showed the maximum solubility of ibuprofen, 1.2 mg/ml. Menthol improved the dissolution rates of ibuprofen from poloxamer gels. Dissolution mechanism showed that the dissolution rate of ibuprofen from the poloxamer gels without menthol was independent of the time, but the drug might be dissolved from the poloxamer gels with menthol by Fickian diffusion. Thus, the poloxamer gels developed using eutectic mixture with menthol, which gave the improved solubility and dissolution of drug, are potential candidates for ibuprofen-loaded transdermal and rectal delivery system.     

A polymeric micellar carrier for the solubilization of biphenyl dimethyl dicarboxylate

A polymeric micelle drug delivery system was developed to enhance the solubility of poorly-water soluble drug, biphenyl dimethyl dicarboxylate, DDB. The block copolymers consisting of poly(D,L-lactide) (PLA) as the hydrophobic segment and methoxy poly(ethylene glycol) (mPEG) as the hydrophilic segment were synthesized and characterized by NMR, DSC and MALDI-TOF mass spectroscopy. The size of the polymeric micelles measured by dynamic light scattering showed a narrow monodisperse size distribution with the average diameter less than 50 nm. The MW of mPEG-PLA, 3000 (MW of mPEG, 2 K; MW of PLA, 1 K), and the presence of hydrophilic and hydrophobic segments on the polymeric micelles were confirmed by MALDI-TOF mass spectroscopy and NMR, respectively. Polymeric micelle solutions of DDB were prepared by three different methods, i.e. the matrix method, emulsion method and dialy-sis method. In the matrix method, DDB solubility was reached to 13.29 mg/mL. The mPEG-PLA 2K-1 K micelle system was compared with the poloxamer 407 micelle system for their critical micelle concentration, micelle size, solubilizing capacity, stability in dilution and physical state. DDB loaded-polymeric micelles prepared by the matrix method showed a significantly increased aqueous solubility (>5000 fold over intrinsic solubility) and were found to be superior to the poloxamer 407 micelles as a drug carrier.     

星形聚合物胶束作为药物载体的研究进展

星形聚合物胶束是一类新型纳米药物载体,它具有独特的分枝结构,所形成的单分子胶束具有理想的粒径和稳定性,可使难溶性药物有效增溶,降低药物毒性,延长体循环时间,提高生物利用度和安全性。星形聚合物胶束作为药物载体具有良好的缓释效果,通过在聚合物表面接枝功能基团可产生靶向释放效果,聚酯结构的星形聚合物还具有良好的降解性能,不在体内蓄积产生毒副作用。本文对星形聚合物的合成及其胶束作为药物载体的理化性质、载药优势、制备方法等的研究进展进行综述。     

Interleukin-2 lipid microspheres. I. development and evaluation of the colloidal drug carrier

Undesirable toxic effects associated with intravenous interleukin-2 (IL2) therapy have limited its use for the treatment of cancer. Therefore, we investigated properties of a colloidal carrier system intended for the delivery of IL2. Lipid microspheres (LMS) are 10% (v/v) soybean oil emulsions stabilized with block copolymers of the poloxamer and poloxamine type. Poloxamers 238, 338, 407 or poloxamine 908 LMS were evaluated for physical stability, in vitro toxicity, and in vivo biodistribution. With the exception of 2% poloxamer 238 LMS, all preparations displayed acceptable stability when stored for 3 months at 4° or 37°C. In addition, all LMS preparations exhibited physical stability when subjected to freeze-thaw cycling and extended periods of freezing. In vitro cellular toxicity was evaluated in a murine cytotoxic T lymphocyte cell line (CTLL-2) and human peripheral blood mononuclear cells (PBMC). The calculated IC₅₀ of LMS was approximately 30 and 10 mg/liter in CTLL-2 cells and PBMC, respectively. Biodistribution studies involving ¹²⁵I-labeled LMS revealed that 2 h after intravenous administration there was significantly greater recovery of the poloxamer 338 and 407 LMS-associated radioactivity, where blood, liver, spleen, and bone marrow accounted for most of the radioactivity. Overall, the data suggest that LMS have the potential to serve as a drug delivery system.     

Transferrin receptor-targeted vitamin E TPGS micelles for brain cancer therapy: preparation,characterization and brain distribution in rats

Abstract

The effective treatment of brain cancer is hindered by the poor transport across the blood–brain barrier (BBB) and the low penetration across the blood–tumor barrier (BTB). The objective of this work was to formulate transferrin-conjugated docetaxel (DTX)-loaded d-alpha-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS or TPGS) micelles for targeted brain cancer therapy. The micelles with and without transferrin conjugation were prepared by the solvent casting method and characterized for their particle size, polydispersity, drug encapsulation efficiency, drug loading, in vitro release study and brain distribution study. Particle sizes of prepared micelles were determined at 25?°C by dynamic light scattering technique. The external surface morphology was determined by transmission electron microscopy analysis and atomic force microscopy. The encapsulation efficiency was determined by spectrophotometery. In vitro release studies of micelles and control formulations were carried out by dialysis bag diffusion method. The particle sizes of the non-targeted and targeted micelles were <20?nm. About 85% of drug encapsulation efficiency was achieved with micelles. The drug release from transferrin-conjugated micelles was sustained for >24?h with 50% of drug release. The in vivo results indicated that transferrin-targeted TPGS micelles could be a promising carrier for brain targeting due to nano-sized drug delivery, solubility enhancement and permeability which provided an improved and prolonged brain targeting of DTX in comparison to the non-targeted micelles and marketed formulation.     

色胺酮纳米胶束的制备及其性质研究

目的制备色胺酮纳米胶束,改善色胺酮的水溶性,并进行体外性质考察。方法以二硬脂酰基磷脂酰乙醇胺-聚乙二醇2000(DSPE-PEG2000)为载体,用溶剂挥发法制备色胺酮纳米胶束,通过正交实验筛选制备胶束的最佳条件,核磁共振氢谱(1 HNMR)验证色胺酮包载于纳米胶束,用芘荧光探针法测定其临界胶束浓度(CMC),用紫外分光光度计测定其包封率和载药率,动态光散射法测定胶束的粒径,以粒径、外观形态和包封率为指标考察胶束的稳定性。结果色胺酮纳米胶束的CMC为8.93×10-6mol·L~(-1),色胺酮与聚合物投药比为0.442 9∶1(mol∶mol),真空干燥1h,水化5min时,胶束的包封率为32.24%±1.37%,载药率为5.468%±0.39%。色胺酮纳米胶束平均粒径为112.5nm,平均分散系数为0.208,4℃条件下胶束可稳定15d以上。结论制备色胺酮纳米胶束,将色胺酮的溶解度提高至1.625mmol·L~(-1),为改善色胺酮生物利用度的研究奠定了基础。     

酸敏释药胶束肿瘤靶向给药系统的研究进展

酸敏释药胶束作为一种新型的靶向给药系统,具有增溶疏水性药物、载药量高,酸敏感释药等优势。可通过物理包埋或酸敏感键共价连接药物的方式包载药物。在肿瘤组织的偏酸环境下,物理包埋载药胶束由于共聚物亲脂嵌段质子化或亲水亲脂嵌段水解分离、共聚物失去两亲性,胶束解聚释药;而以共价连接方式包载的药物经酸敏键断裂释放。现主要从载药方式及释药机制方面探讨酸敏释药胶束作为肿瘤靶向给药系统的研究进展。     

Interleukin-2 lipid microspheres. I. development and evaluation of the colloidal drug carrier

Abstract

Undesirable toxic effects associated with intravenous interleukin-2 (IL2) therapy have limited its use for the treatment of cancer. Therefore, we investigated properties of a colloidal carrier system intended for the delivery of IL2. Lipid microspheres (LMS) are 10% (v/v) soybean oil emulsions stabilized with block copolymers of the poloxamer and poloxamine type. Poloxamers 238, 338, 407 or poloxamine 908 LMS were evaluated for physical stability, in vitro toxicity, and in vivo biodistribution. With the exception of 2% poloxamer 238 LMS, all preparations displayed acceptable stability when stored for 3 months at 4° or 37°C. In addition, all LMS preparations exhibited physical stability when subjected to freeze-thaw cycling and extended periods of freezing. In vitro cellular toxicity was evaluated in a murine cytotoxic T lymphocyte cell line (CTLL-2) and human peripheral blood mononuclear cells (PBMC). The calculated IC₅₀ of LMS was approximately 30 and 10 mg/liter in CTLL-2 cells and PBMC, respectively. Biodistribution studies involving ¹²⁵I-labeled LMS revealed that 2 h after intravenous administration there was significantly greater recovery of the poloxamer 338 and 407 LMS-associated radioactivity, where blood, liver, spleen, and bone marrow accounted for most of the radioactivity. Overall, the data suggest that LMS have the potential to serve as a drug delivery system.     

Organic nanocarriers for cancer drug delivery

A major focus in translational cancer research is the study of nanocarriers as novel delivery systems for chemotherapeutics. Organic vesicular nanocarriers, such as liposomes and micelles, have the advantage of low toxicity and the versatility to carry diverse drugs and conjugate to targeting agents. This offers the potential for combining treatment and diagnosis (theranostics). Successful incorporation into these nanoformulations has been demonstrated for classical chemotherapeutic drugs that are mostly hydrophobic, small interfering RNA, biological therapeutics and specific nanoparticles, such as superparamagnetic nanoparticles. Liposomes and micelles appear to take advantage of the enhanced permeability and retention (EPR) effect in solid tumours to increase accumulation at the target site (passive targeting). This translates to the clinic, where liposomal drug formulations are reported to exhibit higher efficacy and less side effects. Multidrug formulations and combinations with other treatments, for example, radiation or radiofrequency ablation, to trigger drug release from the nanocarrier at the target site, are mostly at the pre-clinical stage. More complex formulations that incorporate treatment agents together with targeting (active targeting) and imaging molecules have also been investigated in in vivo models with encouraging results.     

Triclosan-loaded poloxamine micelles for enhanced topical antibacterial activity against biofilm

Our research group is interested in the study of different technological approaches to treat hospital biofilm as a means to constrain nosocomial-acquired infections. The present work investigated the effect of the incorporation of the antibacterial agent triclosan (TS) into polymeric micelles of poloxamine T1107 (MW=15 kDa, 70 wt% PEO). The aggregation phenomenon was primarily investigated by means of Critical Micellar Concentration in a broad range of pH. Then, the effect of the polymer concentration on the micellar size was evaluated by Dynamic Light Scattering. Solubility levels increased up to 4 orders of magnitude. The drug inclusion affected the micellization, resulting in size increase and micellar fusion. This phenomenon was only apparent in TS-saturated systems. TS-loaded aggregates proved to be active in vitro against a broad spectrum of bacteria but more importantly, also against two representative clinical pathogens: methicilin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VREF). While the former was sensitive to even very low TS levels attainable in poloxamine-free aqueous media, the later was inhibited only when exposed to higher drug levels affordable exclusively using an inclusion system. These findings indicated the release of the drug from the reservoir. Finally, the activity of a TS-containing 5% poloxamine combination of pH 7.4 was assessed on biofilms of Staphylococcus epidermidis. Results showed a significant decrease (p<0.001) in the number of Colony-Formation Units when the biofilm was exposed to the TS/poloxamine as compared to the limited activity of the polymer-free TS control.     

Tunable Surface Plasmon Resonance–Based Remote Actuation of Bimetallic Core-Shell Nanoparticle-Coated Stimuli Responsive Polymer for Switchable Chemo-Photothermal Synergistic Cancer Therapy

New dual light/temperature-responsive nanocarriers were synthesized using bimetallic plasmonic Au-Ag and Ag-Au nanoparticles (NPs) as cores of vehicles which subsequently functionalized with an upper critical solubility temperature–based poly acrylamide-co-acrylonitrile using reversible addition-fragmentation chain transfer for spatiotemporally controlled chemo-photothermal synergistic cancer therapy. The bimetallic cores were assigned to sense wavelengths close to the localized surface plasmon resonance of monometallic NP shell to produce heat which not only can increase the surrounding temperature over the upper critical solubility temperature of polymer to open its valves and promote drug diffusion but also can kill cancerous cells through photothermal effects with increase in environment temperature by nearly 18°C after about 5 min radiation. The bimetallic NPs were shown good reusability even after 5 heating/cooling cycles, and the efficiency of both photothermal/chemotherapic procedures can be modulated by manipulating carrier's concentration and radiation time. In addition, the cytotoxicity of drug-free nanocarriers on normal L929 fibroblast and letrozole-loaded nanocarriers on MDAMB 231 breast-cancer cell lines were investigated in the absence/presence of laser radiation. Finally, the prepared nanocomposites were exhibited switchable on/off drug release in 2 buffered solutions (pH 5.5 and 7.4) with light actuation. The results revealed that the prepared nanocarriers can be served as efficient delivery platforms for remote-control chemophotothermal synergistic cancer therapy.     

In vivo pharmacokinetic and tissue distribution studies in mice of alternative formulations for local and systemic delivery of Paclitaxel: gel, film, prodrug, liposomes and micelles

The aim of this study was to increase the understanding on the pharmacokinetic and tissue distribution of paclitaxel as influenced by formulation approach. For this purpose, various formulations investigated in Swiss mice included liposomes, poloxamer 407 gel and chitosan film for subcutaneous route; and water-soluble methacrylate prodrug, liposomes and poloxamer micelles for systemic administration. During this study, the currently marketed formulation of Cremophor EL of paclitaxel was used as the reference. A highest plasma concentration following intravenous administration of paclitaxel was observed for rigid and 'Stealth((R))' liposomes containing the prodrug while, least was for covalently incorporated paclitaxel micelles. Further, poloxamer micelles demonstrated both the highest mean residence time of 7.34 h and volume of distribution (VSS=4.82 and VZ=5.87 L/kg) for paclitaxel. This was followed by prodrug loaded 'Stealth' liposomes, which showed a mean residence time of 4.96 h but were least distributed into apparent physiological volume (VSS=2.12 and VZ=3.16 L/kg). These results clearly signify the role of formulation/excipient in drug disposition and possible interactions. Importantly, due to decrease in the clearance rate of drug, the area under curve values of paclitaxel increased by 1.64- and 2.5-fold for micellar and prodrug loaded 'Stealth' liposomal formulations, respectively over reference formulation. While thermoreversible gels served to decrease plasma concentration of paclitaxel (8-fold) after subcutaneous administration, systemic levels were totally absent after implantation of films. In tissue distribution studies, maximum percent of paclitaxel was observed in liver for reference formulation, conventional liposomes and micelles whereas highest levels of prodrug and 'Stealth((R))' liposomes were in kidney and spleen, respectively. The novel formulations significantly altered tissue accumulation profiles of paclitaxel relative to the reference formulation, for example, reduction in uptake by heart from liposomes and micelles, as well as the major recognition mechanism for elimination. It is proposed that a combination therapy with liposomes and micelles of paclitaxel for systemic delivery along with implantation of chitosan film for local delivery, may serve not only to improve patient compliance by obliterating the need to administer Cremophor EL, but also increase patient survival.