Thermosensitive and biodegradable polymeric micelles for paclitaxel delivery (original) (raw)
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European Journal of Pharmaceutics and Biopharmaceutics, 2009
Paclitaxel (PTX) is an effective anti-cancer drug currently used to treat a wide variety of cancers. Unfortunately, nonaqueous vehicle containing Cremophor Ò EL is associated with serious clinical side effects. This work aimed to evaluate the ability of polymeric micelles to (i) solubilize PTX without Cremophor Ò EL and to be used as a (ii) safe and (iii) effective delivery system for PTX. Hence, we developed novel selfassembling poly(ethyleneglycol) 750 -block-poly(e-caprolactone-co-trimethylenecarbonate) (PEG-p-(CLco-TMC)) polymeric micelles which form micelles spontaneously in aqueous solution. The solubility of PTX increased up to three orders of magnitude. The PTX-loaded micelles showed a slow release of PTX with no burst effect. The HeLa cells viability assessed by the MTT test was lower for PTX-loaded micelles than for Taxol Ò (IC 50 10.6 vs. 17.6 lg/ml). When solubilized in micelles, PTX induced apoptosis comparable with Taxol Ò . The maximum tolerated doses (MTD) of PTX-loaded micelles and Taxol Ò in mice were 80 mg/kg and 13.5 mg/kg, respectively, after intraperitoneal administration; and 45 mg/kg and 13.5 mg/kg, respectively, after intravenous administration. Similar anti-tumor efficacy of PTX-loaded micelles and Taxol Ò was observed at the dose of 13.5 mg/kg on TLT-tumor-bearing mice, while the body weight loss was only observed in Taxol Ò group. However, as higher dose was tolerated (80 mg/kg -IP), a higher growth delay was induced with PTX-loaded micelles. These results demonstrated that PTX-loaded self-assembling micelles present a similar anti-tumor efficacy as Taxol Ò , but significantly reduced the toxicity allowing the increase in the dose for better therapeutic response.
Biomacromolecules, 2007
The purpose of this investigation was to characterize the in vitro stability and in vivo disposition of paclitaxel in rats after solubilization of paclitaxel into hydrotropic polymeric micelles. The amphiphilic block copolymers consisted of micellar a shell-forming poly(ethylene glycol) (PEG) block and a core-forming poly(2-(4-vinylbenzyloxy)-N,N-diethylnicotinamide) (P(VBODENA)) block. N,N-Diethylnicotinamide (DENA) in the micellar inner core resulted in effective paclitaxel solubilization and stabilization. Solubilization of paclitaxel using polymeric micelles of poly (ethylene glycol)-b-P(D,L-lactide) (PEG-b-PLA) served as a control for the stability study. Up to 37.4 wt% paclitaxel could be loaded in PEG-b-P(VBODENA) micelles, whereas the maximum loading amount for PEG-b-PLA micelles was 27.6 wt%. Thermal analysis showed that paclitaxel in the polymeric micelles existed in the molecularly dispersed amorphous state even at loadings over 30 wt%. Paclitaxel-loaded hydrotropic polymeric micelles retained their stability in water for weeks, whereas paclitaxel-loaded PEG-b-PLA micelles precipitated in a few days. Hydrotropic polymer micelles were more effective than PEG-PLA micelle formulations in inhibiting the proliferation of human cancer cells. Paclitaxel in hydrotropic polymer micelles was administered orally (3.8 mg/kg), intravenously (2.5 mg/kg) or via the portal vein (2.5 mg/kg) to rats. The oral bioavailability was 12.4% of the intravenous administration. Our data suggest that polymeric micelles with a hydrotropic structure are superior as a carrier of paclitaxel due to a high solubilizing capacity combined with long-term stability which has not been accomplished by other existing polymeric micelle systems.
International journal of biological macromolecules, 2015
In this study a novel receptor-targeted micelle delivery system based on tocopherol succinate-chitosan-polyethylene glycol-folic acid (TS-CS-PEG-FA) was synthesized and loaded with paclitaxel (PTX). Physicochemical properties of the micelles such as critical micelle concentration, micelle size, entrapment efficiency, stability, release properties, cellular uptake and in vitro cytotoxicity were investigated in detail. Furthermore, the pharmacokinetics and tissue distributions of PTX-loaded micelles were evaluated in Balb/c mice and compared with Anzatax(®) (PTX in Cremophor EL(®)). Particle sizes and zeta potentials of the micelles were in the range of 162.3-277.1nm and 18.5-28.3mV, respectively. The drug entrapment efficiencies of the micelles were within 53.6-82.5% (w/w). Cytotoxicity assay demonstrated increased cytotoxic activity of PTX-loaded TS-CS-PEG-FA micelles compared to free PTX. The Vd and t1/2β of PTX-loaded TS-CS-PEG-FA were increased by 2.76- and 2.05-fold, respectivel...
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.
Hydrotropic agents for study of in vitro paclitaxel release from polymeric micelles
Journal of Controlled Release, 2004
A new experimental method for in vitro release studies of poorly soluble drugs from polymeric micelle systems was developed using a hydrotropic agent, sodium salicylate. It is difficult to maintain a good sink condition for poorly water-soluble drugs, such as paclitaxel (PTX), because of their low aqueous solubility. In this study, a good sink condition for PTX was achieved by using aqueous sodium salicylate solution which solubilized more than 10 times the total amount of PTX incorporated in polymeric micelles. Sodium salicylate at 1 M concentration increased the aqueous PTX solubility by 100 times without destroying the micellar structure of poly(ethylene glycol)-block-poly(phenylalanine) (PEG-b-PPhe) copolymer. PTX was continuously released from PEG-b-PPhe micelles in the hydrotropic release medium. The hydrotropic solution presents a simple method for studying in vitro release behavior of poorly soluble drugs from polymeric micelles in aqueous media.
Polymeric micelles for the pH-dependent controlled, continuous low dose release of paclitaxel
Biomaterials, 2010
Poly(ethylene glycol)-block-poly(aspartate-hydrazide) (PEG-p(Asp-Hyd)) was modified using either levulinic acid (LEV) or 4-acetyl benzoic acid (4AB) attached via hydrazone bonds. Paclitaxel (PTX) conjugated to the linkers formed PEG-p(Asp-Hyd-LEV-PTX) and PEG-p(Asp-Hyd-4AB-PTX). PEG-p(Asp-Hyd-LEV-PTX) and PEG-p(Asp-Hyd-4AB-PTX) assemble into unimodal polymeric micelles with diameters of 42 nm and 137 nm, respectively. PEG-p(Asp-Hyd-LEV-PTX) and PEG-p(Asp-Hyd-4AB-PTX) at a 1:1 and 1:5 molar ratio assemble into unimodal mixed polymeric micelles with diameters of 85 and 113 nm, respectively. PEG-p(Asp-Hyd-LEV-PTX) micelles release LEV-PTX faster at pH 5.0 than at pH 7.4 over 24 h. At pH 7.4 mixed polymeric micelles at 1:5 ratio show no difference in LEV-PTX release from PEG-p(Asp-Hyd-LEV-PTX) micelles. Mixed polymeric micelles at 1:5 molar ratio gradually release LEV-PTX at pH 5.0, with no release of 4AB-PTX. PEG-p(Asp-Hyd-LEV-PTX) micelles and mixed polymeric micelles exert comparable cytotoxicity against SK-OV-3 and MCF-7 cancer cell lines. In summary, mixed polymeric micelles based on PEG-p(Asp-Hyd-LEV-PTX) and PEG-p(Asp-Hyd-4AB-PTX) offer prospects for pH-dependent release of PTX, offering a novel prodrug strategy for adjusting its pharmacokinetic and pharmacodynamic properties for cancer therapy. If successful this delivery system offers an alternative new mode of delivery for paclitaxel with a new scope for its efficacy along with a minimal synthetic framework needed to accomplish this.
Pharmaceutical Research, 2008
Purpose. Develop a Cremophor \ and solvent free formulation of paclitaxel using amphiphilic block copolymer micelles of poly(ethylene glycol)-b-poly((-caprolactone) (PEG-b-PCL) and characterize their release, solubility, cytotoxicity, tolerability, and disposition. Methods. Hydrophobic prodrugs of paclitaxel were synthesized via DCC/DMAP or anhydride chemistry to overcome the poor loading (<1% w/w) of paclitaxel in micelles of PEG-b-PCL. Micelles were prepared by a co-solvent extraction technique. A micellar formulation of paclitaxel prodrug (PAX7 ¶C 6 ) was dosed intravenously to rats (10 mg/kg) and compared to Taxol \ (paclitaxel in CrEL:EtOH) and PAX7 ¶C 6 in CrEL:EtOH as controls at the same dose. Pharmacokinetic parameters and tissue distribution were assessed. Results. Paclitaxel prodrugs had solubilities >5 mg/ml in PEG-b-PCL micelles. Resulting PEG-b-PCL micelles contained 17-22% w/w prodrug and were less than 50 nm in diameter. PEG-b-PCL micelles released paclitaxel prodrugs over several days, t 1/2 >3 d. Only the 7 ¶derivative of paclitaxel with the shortest acylchain 7 ¶hexonoate (PAX7 ¶C 6 ) maintained cytotoxic activity similar to unmodified paclitaxel. PAX7 ¶C 6 micelles demonstrated an increase in area under the curve, half-life, and mean residence time while total clearance and volume of distribution decreased. Conclusions. Paclitaxel prodrugs in PEG-b-PCL micelle nanocarriers augment the disposition and increase tolerability making further studies on tumor efficacy warranted.
Stabilized micelles as delivery vehicles for paclitaxel
International Journal of Pharmaceutics, 2012
Paclitaxel is an antineoplastic drug used against a variety of tumors, but its low aqueous solubility and active removal caused by P-glycoprotein in the intestinal cells hinder its oral administration. In our study, new type of stabilized Pluronic micelles were developed and evaluated as carriers for paclitaxel delivery via oral or intravenous route. The pre-stabilized micelles were loaded with paclitaxel by simple solvent/evaporation technique achieving high encapsulation efficiency of 70 %. Gastrointestinal transit of the developed micelles was evaluated by oral administration of rhodamine-labeled micelles in rats. Our results showed prolonged gastrointestinal residence of the marker encapsulated into micelles, compared to a solution containing free marker. Further, the oral administration of micelles in mice showed high area under curve of micellar paclitaxel (similar to the area of i.v. Taxol ), longer mean residence time (9-times longer than i.v. Taxol ) and high distribution volume (2-fold higher than i.v. Taxol ) indicating an efficient oral absorption of paclitaxel delivered by micelles. Intravenous administration of micelles also showed a significant improvement of pharmacokinetic parameters of micellar paclitaxel vs. Taxol , in particular higher area under curve (1.2-fold), 5-times longer mean residence time and lower clearance, indicating longer systemic circulation of the micelles.
Advanced Drug Delivery Reviews, 2002
® A number of hypersensitivity reactions have been attributed to the presence of Cremophor EL in the current formulation for paclitaxel. This has led to the development of formulations for paclitaxel employing polyether-polyester diblock copolymers as micelle forming carriers. Diblock copolymers of methoxypolyethylene glycol-block-poly(D,L-lactide) (MePEG:PDLLA) were synthesized from monomers of D,L-lactide and MePEG by a ring opening bulk polymerization in the presence of stannous octoate. Up to 25% paclitaxel could be loaded into matrices of MePEG:PDLLA (60:40, MePEG molecular weight of 2000) using the solution casting method. Dissolution of paclitaxel / copolymer matrices in aqueous media resulted in complete solubilization of paclitaxel within the hydrophobic PDLLA core of the micelles. This review article describes the synthetic reaction conditions influencing the degree of conversion of monomer to copolymer, thermal properties, critical micelle concentrations of copolymers, methods of incorporation of paclitaxel into copolymer matrices and subsequent constitution in aqueous media and biological evaluations of micellar paclitaxel.