Micelles from lipid derivatives of water-soluble polymers as delivery systems for poorly soluble drugs (original) (raw)
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Polymeric micelles as a drug carrier fro tumor targeting
Polymeric micelle can be targeted to tumor site by passive and active mechanism. Some inherent properties of polymeric micelle such as size in nanorange, stability in plasma, longevity in vivo, and pathological characteristics of tumor make polymeric micelles to be targeted at the tumor site by passive mechanism called enhanced permeability and retention effect. Polymeric micelle formed from the amphiphilic block copolymer is suitable for encapsulation of poorly water soluble, hydrophobic anticancer drugs. Other characteristics of polymeric micelles such as separated functionality at the outer shell are useful for targeting the anticancer drug to tumor by active mechanisms. Polymeric micelles can be conjugated with many ligands such as antibodies fragments, epidermal growth factors, α 2 -glycoprotein, transferrine, and folate to target micelles to cancer cells. Application of heat and ultrasound are the alternative methods to enhance drug accumulation in tumoral cells. Targeting using micelles can also be done to tumor angiogenesis which is the potentially promising target for anticancer drugs. This review summarizes about recently available information regarding targeting the anticancer drug to the tumor site using polymeric micelles.
Journal of Drug Targeting, 2005
Paclitaxel-loaded mixed polymeric micelles consisting of poly(ethylene glycol)-distearoyl phosphoethanolamine conjugates (PEG-PE), solid triglycerides (ST), and cationic Lipofectin® lipids (LL) have been prepared. Micelles with the optimized composition (PEG-PE/ST/LL/paclitaxel = 12/12/2/1 by weight) had an average micelle size of about 100 nm, and zeta-potential of about 26 mV. Micelles were stable and did not release paclitaxel when stored at 4°C in the darkness (just 2.9% of paclitaxel have been lost after 4 months with the particle size remaining unchanged). The release of paclitaxel from such micelles at room temperature was also insignificant. However, at 37°C, approx. 16% of paclitaxel was released from PEG-PE/ST/LL/paclitaxel micelles in 72 h, probably, because of phase transition in the ST-containing micelle core. In vitro anticancer effects of PEG-PE/ ST/LL/paclitaxel and control micelles were evaluated using human mammary adenocarcinoma (BT-20) and human ovarian carcinoma (A2780) cell lines. Paclitaxel in PEG-PE/ST/LL micelles demonstrated the maximum anti-cancer activity. Cellular uptake of fluorescently-labeled paclitaxelcontaining micelles by BT-20 cells was investigated using a fluorescence microscopy. It seems that PEG-PE/ST/LL micelles, unlike micelles without the LL component, could escape from endosomes and enter the cytoplasm of BT-20 cancer cells thus increasing the anticancer efficiency of the micellar paclitaxel.
European Journal of Pharmaceutics and Biopharmaceutics, 2006
The objective of this study is to investigate the solubilization of poorly water-soluble anticancer drugs, octaethylporphine (OEP), meso-tetraphenyl porphine (mTPP) and camptothecin (CPT), in Pluronic and polyethylene glycol-distearoylphosphatidylethanolamine (PEG-DSPE) polymeric micelles. Three different Pluronic and PEG-DSPE polymers with various chain lengths were chosen and micelle formulations were prepared by using various drug:polymer ratios. Formulations were characterized by critical micellization concentration (CMC) values of copolymers, micelle particle size and distribution, zeta potential, loading efficiency and stability. Polymers formed very stable, low CMC micelles with smaller sizes than 100 nm. It was shown that drug loading efficiency highly depends on the polymer type, drug type and their ratios. The most efficient drug loading was obtained by loading mTPP in PEG 2000-DSPE and Pluronic F127 micelles. This result is attributed to phenyl groups in mTPP might lead to attraction between alkyl groups in the polymer and increase drug incorporation. PEG-DSPE formulations had higher zeta potential values indicating that they would be more stable against aggregation than Pluronic micelles. From the drug assay aspect Pluronic micelles remained more stable in 3-month long stability test. These results showed that besides their solubilizing effects, polymeric micelles could be useful as novel drug carriers for hydrophobic drugs.
International journal of pharmaceutics, 2006
Mixed micelles prepared of poly(ethylene glycol)2000-phosphatidyl ethanolamine conjugate (PEG(2000)-PE) and d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) in 1:1 molar ratio have been investigated. Micelle formation was confirmed by NMR spectroscopy. CMC of the micelles was found to be 1.5 x 10(-5)M. Poorly soluble anti-cancer drug paclitaxel (PCL) was efficiently solubilized in 15 nm non-toxic PEG-PE/TPGS micelles. PCL entrapment was quite stable with only about 20% of the incorporated drug released from micelles after 48 h at 37 degrees C. In addition, PCL-containing PEG(2000)-PE/TPGS micelles were stable in vitro under various conditions modeling the physiological ones, in particular, at low pH values and in the presence of bile acids, which is especially important for their possible oral administration. Fluorescently labeled micelles demonstrated time-dependent internalization by human colon adenocarcinoma cell line, Caco-2. The internalization of PEG(2000)-PE/TPGS...
Multi-drug loaded polymeric micelles for simultaneous delivery of poorly soluble anticancer drugs
Journal of Controlled Release, 2009
Current clinical and preclinical anticancer formulations are limited by their use of toxic excipients and stability issues upon combining different drug formulations. We have found that poly(ethylene glycol)-block-poly(d,l lactic acid) (PEG-b-PLA) micelles can deliver multiple poorly water-soluble drugs at clinically relevant doses. Paclitaxel (PTX), etoposide (ETO), docetaxel (DCTX) and 17-AAG were solubilized individually in PEG-b-PLA micelles. Combinations of PTX/17-AAG, ETO/ 17-AAG, DCTX/17-AAG and PTX/ETO/17-AAG were also solubilized in PEG-b-PLA micelles. PEG-b-PLA micelles were characterized in terms of drug loading, size, stability and drug release. All anticancer agents in all combinations were all solubilized at the level of mg/mL and were stable for 24 hours in the 2 and 3 drug combination PEG-b-PLA micelles. The stability of the 2 and 3 drug combination PEG-b-PLA micelles was due to the presence of 17-AAG. In vitro, t 1/2 values for 2 and 3 drug combination PEG-b-PLA micelles spanned 1-5 hrs. PEG-b-PLA micelles offer a promising alternative for combination drug therapy without formulation related side effects.
Polymeric Micelles for the Delivery of Poorly Soluble Drugs
John Wiley & Sons, Ltd eBooks, 2013
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Pharmaceutical Research, 2009
Purpose The aim of this study is to develop novel polylactide/poly(ethylene glycol) (PLA/PEG) micelles as carrier of hydrophobic drug (paclitaxel) by direct dissolution method without using any organic solvents. The in vitro and in vivo release properties were studied in comparison with micelles prepared by dialysis. Methods Drug encapsulation efficiency (EE) and loading content (LC) of the micelles were evaluated by high-performance liquid chromatography. Micelle diameters and structures were determined by dynamic light scattering and transmission electron microscopy. In vitro release was performed in phosphate-buffered saline (pH 7.4) at 37°C, and in vivo experiments were realized in lung cancer-bearing mice. Results Similar EE and LC values were obtained for micelles by direct dissolution method and those by dialysis. L- and D-PLA/PEG mixed micelles present higher drug encapsulation ability than separate micelles due to stereocomplexation. Micelle diameters are enlarged by drug-loading. Faster drug release was obtained for micelles by direct dissolution than those by dialysis. Compared with current clinical formulation and micelles by dialysis, paclitaxel-loaded micelles by direct dissolution showed the highest antitumor ability. Conclusion The L- and D-PLA/PEG mixed micelles by direct dissolution method present many advantages such as easy formulation and absence of toxic organic solvents, which shows great potential as carrier of hydrophobic drugs.
Drug Development and Industrial Pharmacy, 2017
Co-delivery strategy has been proposed to minimize the amount of each drug and to achieve the synergistic effect for cancer therapies. A conjugate of the antitumor drug, doxorubicin, with diblock methoxy poly (ethylene glycol)-poly caprolactone (mPEG-PCL) copolymer was synthesized by the reaction of mPEG-PCL copolymer with doxorubicin in the presence of pnitrophenylchloroformate. The conjugated copolymer was characterized in vitro by 1 H NMR, FTIR, DSC and GPC techniques. Then, the doxorubicin conjugated mPEG-PCL(DOX-mPEG-PCL) was self-assembled into micelles in the presence of curcumin in aqueous solution.The resulting micelles were characterized further by various techniques such as dynamic light scattering (DLS) and atomic force microscopy (AFM).The encapsulation efficiency of doxorubicin and curcumin were 82.31±3.32% and 78.15±3.14%, respectively. The results revealed that the micelles formed by the DOX-mPEG-PCL with and without curcumin have spherical structure withthe average size of 116 and 134 nm respectively.The release behavior of curcumin and doxorubicin loaded to micelles were investigated in different media. The release rate of micelles consisted of the conjugated copolymer was dependent on pH asit was higher at lower pH than in neutral condition. Another feature of the conjugated micelles was a sustained release profile. The cytotoxicity of micelles were evaluated by MTT (3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyltetrazolium bromide, atetrazole) assay on lung cancer A549 cell lines. In vitro cytotoxicity assay showed that the mPEG-PCL copolymer did not affect the growth of A549 cells. The cytotoxic activity of the micelles against A549 cells was greater than free doxorubicin and free curcumin.
International journal of Pharmacy and Pharmaceutical Sciences, 2014
Objective: Curcumine (CUR) and rapamycin (RAPA) are two potent hydrophobic anticancer drugs. The clinical and preclinical applications of anticancer formulations are limited due to use of toxic excipients and poor bioavailability. In the present study, an approach has been made to develop CUR and RAPA loaded MePEG/PCL di-block copolymeric micelles keeping in the view to make excipient free formulation with slow release of drugs. Methods: The CUR and RAPA loaded MePEG/PCL di-block copolymeric micelles were prepared. Physico-chemical characters like size, surface charge and encapsulation efficiency were measured. The in vitro release studies was carried out in pH 7.4 to evaluate the sustained release properties of micelles. Results: MePEG/PCL di-block copolymeric micelles were efficiently encapsulate both the drugs, i. e. CUR (~ 64 %) and RAPA (~ 94 %) in the core and have loading capacity of ~ 12 % (CUR) and ~ 29 % (RAPA). The zetasizer measurement shows that particles have size range 128 nm to 176 nm with a negative zeta potential. SEM and AFM studies reveled that micelles have smooth exterior surface. The XRD and DSC studies explain that the drugs are uniformly distributed in the polymer matrix. The dual drug loaded micelles have sustained in vitro drug release activity as estimated in phosphate buffer (pH 7.4). Conclusion: These MePEG/PCL di-block copolymeric micelles are capable of carrying both the hydrophobic anticancer drugs and the encouraging results suggest further studies to evaluate the bioavailability parameters as well as suitability of the formulation.