Micelles of Different Morphologies—Advantages of Worm-like Filomicelles of PEO-PCL in Paclitaxel Delivery

Purpose

Worm-like and spherical micelles are both prepared here from the same amphiphilic diblock copolymer, poly(ethylene oxide)-b-poly (ε-caprolactone) (PEO [5 kDa]–PCL [6.5 kDa]) in order to compare loading and delivery of hydrophobic drugs.

Materials and Methods

Worm-like micelles of this degradable copolymer are nanometers in cross-section and spontaneously assemble to stable lengths of microns, resembling filoviruses in some respects and thus suggesting the moniker ‘filomicelles’. The highly flexible worm-like micelles can also be sonicated to generate kinetically stable spherical micelles composed of the same copolymer.

Results

The fission process exploits the finding that the PCL cores are fluid, rather than glassy or crystalline, and core-loading of the hydrophobic anticancer drug delivery, paclitaxel (TAX) shows that the worm-like micelles load and solubilize twice as much drug as spherical micelles. In cytotoxicity tests that compare to the clinically prevalent solubilizer, Cremophor^® EL, both micellar carriers are far less toxic, and both types of TAX-loaded micelles also show fivefold greater anticancer activity on A549 human lung cancer cells.

Conclusion

PEO–PCL based worm-like filomicelles appear to be promising pharmaceutical nanocarriers with improved solubilization efficiency and comparable stability to spherical micelles, as well as better safety and efficacy in vitro compared to the prevalent Cremophor^® EL TAX formulation.

     

Paclitaxel治疗难治性卵巢癌

Paclitaxel（PL）系一种新型抗肿瘤药物。文中详细报告了本品治疗100例难治性卵巢癌患者的疗效。本组100例卵巢癌患者，以往均对化疗和钥治疗无效。平均年龄59．4土11．4岁。罹患癌肿时间＜12月～＞25个月。32%伴有胶水，57%伴腹膜癌肿。PL的用法为24／J＼时135mg／m2，静滴，用药见天。在使用PL之前，所有患者均予以西咪替丁300mg本海拉明50mg）静滴，同时在应用PL之前，予以口服20mg，以防止发生急性过敏反应。若病人不耐受PL，则在开始时予以皮下注射粒细胞集群刺激因子每天sndkg100例难治性卵巢癌患者接受PL治疗由中值疗程为5个（…     

Random Mutagenesis of β-Tubulin Defines a Set of Dispersed Mutations That Confer Paclitaxel Resistance

Purpose

Previous research showed that mutations in β1-tubulin are frequently involved in paclitaxel resistance but the question of whether the mutations are restricted by cell-type specific differences remains obscure.

Methods

To circumvent cellular constraints, we randomly mutagenized β-tubulin cDNA, transfected it into CHO cells, and selected for paclitaxel resistance.

Results

A total of 26 β1-tubulin mutations scattered throughout the sequence were identified and a randomly chosen subset were confirmed to confer paclitaxel resistance using site-directed mutagenesis of β-tubulin cDNA and transfection into wild-type cells. Immunofluorescence microscopy and biochemical fractionation studies indicated that cells expressing mutant tubulin had decreased microtubule polymer and frequently suffered mitotic defects that led to the formation of large multinucleated cells, suggesting a resistance mechanism that involves destabilization of the microtubule network. Consistent with this conclusion, the mutations were predominantly located in regions that are likely to be involved in lateral or longitudinal subunit interactions. Notably, fourteen of the new mutations overlapped previously reported mutations in drug resistant cells or in patients with developmental brain abnormalities.

Conclusions

A random mutagenesis approach allowed isolation of a wider array of drug resistance mutations and demonstrated that similar mutations can cause paclitaxel resistance and human neuronal abnormalities.     

Thermosensitive Micelles–Hydrogel Hybrid System Based on Poloxamer 407 for Localized Delivery of Paclitaxel

A thermosensitive micelles–hydrogel hybrid system based on Poloxamer 407 (P407) was prepared to resolve the fast erosion and low loading capability of lipophilic drug of P407 gels for local chemotherapy. Different amounts of glutaraldehyde (GA) were applied to generate cross-linked networks with carboxymethyl chitosan (CMCS) interpenetrated in P407 gels, in which paclitaxel (PTX)-loaded N-octyl-O-sulfate chitosan micelles (PTX-M) were dispersed uniformly. The in vitro characteristics of CMCS-modified P407 gels (PTX-M-MG) were performed by examining the viscosity, swelling ratio, mechanical property, and drug release, while the in vivo evaluation included tissue distribution and anticancer efficacy through in-tratumoral administration in hepatoma solidity cell (Heps) tumor-bearing mice. The results showed that PTX-M-MG containing 0.05% (w/v) GA possessed lower viscosity, higher swelling ratio, stronger mechanical property, and longer term drug release, in which the loading efficiency of PTX was enlarged by the introduction of PTX-M. Moreover, PTX-M-MG revealed a prolonged retention at tumor sites, lasting for 20 days, and a superior tumor inhibition rate (64.27%) with reduced toxicity compared with Taxol®, PTX-M, and PTX-M loaded unmodified P407 gels (PTX-M-P407). It can be concluded that PTX-M-MG is a promising local delivery system for hydrophobic drug in cancer therapy, providing both improved efficacy and relieved side effects. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:2707–2717, 2013     

The Effect of Novel Surfactants and Solutol® HS 15 on Paclitaxel Aqueous Solubility and Permeability Across a Caco-2 Monolayer

The effect of novel surfactants on the aqueous solubility and the permeability of paclitaxel across a Caco-2 cell monolayer were examined in this work. The solubility and permeability of paclitaxel was evaluated in the presence of four soft surfactants (SS) KXN441, KXN424, KXN437, and KXN 337 and Solutol® HS15. All surfactants increased the aqueous solubility of paclitaxel. Caco-2 cell membrane integrity in the presence of SS and Solutol® HS15 was assessed by mannitol permeability and LDH release. All surfactants were tested at 0.5 × CMC, 5 × CMC and 1.5 mM concentrations. The effect of SSs on paclitaxel permeability was concentration dependent. At all concentrations tested, KXN 441 and Solutol® HS 15 showed partially inhibition of drug efflux with no discernable change in mannitol permeability or cytotoxicity as observed with LDH release. At these concentrations, other SSs exhibited some partial efflux inhibition along with compromised membrane integrity and increasing mannitol permeability. In conclusion, all SSs were able to increase the aqueous solubility and permeability of paclitaxel across Caco-2 cells monolayer. However, KXN441 and Solutol® HS15 were able to enhance paclitaxel permeability across Caco-2 monolayer without cytotoxicity.     

Incorporation With Dendrimer-Like Biopolymer Leads to Improved Soluble Amount and In Vitro Anticancer Efficacy of Paclitaxel

The aim of this study was to explore the solubilization efficacy of octenylsuccinate hydroxypropyl phytoglycogen (OHPP), an amphiphilic dendrimer-like biopolymer, in improving the soluble amount and efficacy of paclitaxel (PTX), a potent anticancer active pharmaceutical ingredient. PTX was incorporated with OHPP in the form of solid dispersion (PTX-OHPP SD), which was characterized for its PTX crystallinity, interactions between PTX and OHPP, PTX soluble amount and dissolution profile, and in vitro inhibitory efficacy against cancer cell lines. The incorporation with OHPP led to the amorphous state of PTX. FTIR spectra showed potential hydrogen bonding between PTX and OHPP, and hydrophobic interaction could play an important role in the association of PTX molecules with OHPP particulates. The soluble amount of PTX with PTX-OHPP SD was >14,000 times that of PTX alone. During dissolution, over 70% PTX dissolved in 5 min and this soluble amount was maintained for at least 180 min. With the 3 cancer cell lines tested, the PTX of PTX-OHPP SD showed a much lower IC₅₀ than the dimethyl sulfoxide–assisted PTX solutions. Based on the result, the mechanism of using OHPP as a highly potent solubilizer for PTX was discussed.     

Drug eluting stents: friend or foe? A review of cellular mechanisms behind the effects of Paclitaxel and sirolimus eluting stents

Coronary artery disease continues to be an important cause of mortality and morbidity. Sirolimus and paclitaxel eluting stents have become an important treatment for patients undergoing revascularization from coronary blockages. These drug eluting stents have enjoyed great success initially in preventing recurrences of adverse cardiac events and decreasing the incidences of repeat revascularizations. However, adverse effects, such as thrombosis, emanating from the use of these drug eluting stents has recently come to focus. Hence a better understanding of the mechanism of action of these drugs in preventing restenosis is important for the long term success and potential betterment of drug eluting stent technology. Herein we review and discuss the pathophysiology of restenosis, the basic mechanism of action of sirolimus and paclitaxel eluting stents and their limitations so as to create a scope for more efficient and novel drug eluting stents in the future.     

Paclitaxel: a hope for advanced non-small cell lung cancer?

Recent studies have shown that paclitaxel (Taxol); Bristol-Myers Squibb Co., Princeton, NJ) is an active agent in the treatment of advanced non-small cell lung cancer (NSCLC). Early trials in patients with advanced NSCLC utilised a 24 h infusion schedule and reported objective tumour responses in 21 - 24% of patients. Shorter infusion schedules have equivalent efficacy, and combined results from 14 separate trials of single agent paclitaxel in advanced NSCLC show an overall tumour response rate of 26%. Alternative schedules of paclitaxel from the traditional regimen every three weeks are under active investigation, but it is premature to assess whether these will yield improved efficacy for patients with advanced NSCLC. A single multicentre randomised trial of paclitaxel versus best supportive care in advanced NSCLC showed a significant survival advantage for the chemotherapy arm. Two large randomised Phase III trials have shown that paclitaxel and cisplatin is modestly more effective than cisplatin and podophyllotoxin combinations. The addition of cisplatin or carboplatin to paclitaxel results in higher response rates than for each of the drugs as single agents, but it is unclear whether the combinations yield superior survival or quality of life compared to single agent paclitaxel, or to other paclitaxel-containing regimens.     

04041 Paclitaxel poliglumex对强烈治疗后的卵巢癌患者疗效令人鼓舞

美国的研究者称，Cell Therapeutics公司的Paclitaxel poliglumex(CT2103，Xyotax)(Ⅰ)在预先强烈治疗过的卵巢癌的病人，具有令人鼓舞的活性。     

The effects of PGE2 and PGF2α on rhythmic contractions of sphincter of Oddi

• 1.1. Spontaneous rhythmic activity observed in some of the guinea-pig sphincter of Oddi preparations was completely abolished by PGE₂ (10⁻⁸ M) but not altered by PGF_2α (10⁻⁶ M).
• 2.2. Indomethacin (10⁻⁵ M), a cyclooxygenase inhibitor, elicited long-lasting rhythmic contractions in 50% of the preparations tested, which did not show any spontaneous activity. PGE₂ (10⁻⁸ M) completely inhibited, however PGF_2α (10⁻⁸-10⁻⁶ M) did not change the rhythmic contractions induced by indomethacin.
• 3.3. Both initial phasic contraction and the frequency and amplitude of peristaltic waves induced by ACh (10⁻³ M) were increased by indomethacin (10⁻⁵ M), decreased by PGE₂ (10⁻⁷ M) and not altered by PGF_2α (10⁻⁷ M).

     

A Folate Receptor–Targeted Lipid Nanoparticle Formulation for a Lipophilic Paclitaxel Prodrug

No HeadingPurpose. The anticancer drug paclitaxel has poor aqueous solubility and is difficult to formulate in a lipid-based formulation due to its limited lipid solubility. Paclitaxel-7-carbonyl-cholesterol (Tax-Chol), a prodrug of paclitaxel with increased lipophilicity, was therefore synthesized and evaluated for incorporation into a lipid nanoparticle (LN) formulation, which also contained folate-polyethylene glycol-cholesterol (f-PEG-Chol) as a ligand that targets the tumor marker folate receptor (FR). This novel formulation was designed for prolonged systemic circulation and selective targeting of tumor cells with amplified FR expression.Methods. Tax-Chol was synthesized. FR-targeted LNs, composed of distearoyl phosphatidylcholine (DSPC)/triolein/Chol oleate/PEG-Chol/f-PEG-Chol (40:40:18:2.0:0.5, mole/mole), were then prepared by solvent dilution followed by diafiltration. FR-targeted LNs containing Tax-Chol were then evaluated for cytotoxicity in KB, a human oral carcinoma cell line, and M109, a murine lung carcinoma cell line, both of which are FR(+) and in FR(–) Chinese hamster ovary (CHO) cells. Furthermore, tumor growth inhibition and animal survival in response to treatment with FR-targeted LNs and control formulations were evaluated in BALB/c mice bearing subcutaneously engrafted M109 tumors.Results. The LNs had a mean diameter of 130 nm and Tax-Chol incoporation efficiency of greater than 90% and exhibited excellent colloidal stability. FR-targeted LNs showed greater uptake and cytotoxicity in FR(+) KB and M109 cells than nontargeted LNs. Furthermore, treatment of mice bearing M109 tumors with FR-targeted LNs resulted in significantly greater tumor growth inhibition and animal survival compared to treatment with nontargeted LNs or paclitaxel formulated in Cremophor EL.Conclusions. FR-targeted LNs containing Tax-Chol are a promising novel formulation for the treatment of FR(+) tumors and further preclinical studies are warranted.     

Paclitaxel nanosuspensions for targeted chemotherapy – nanosuspension preparation,characterization, and use

Abstract

Objective: The purpose of this work was to prepare a stable paclitaxel nanosuspension and test it for potential use as a targeted chemotherapeutic. Different particle coatings were employed to assess their impact on cellular uptake in vitro. In vivo work was then performed to demonstrate efficacy in tumor-bearing mouse models.

Materials and method: Paclitaxel nanosuspensions were prepared using a homogenization process and coated with excipients. Surface charge was measured by zeta potential, potency by high-performance liquid chromatography, and solubility using an in-line UV probe. Cellular uptake studies were performed via flow cytometry. In vivo experiments were performed to determine residence time, maximum tolerated dose, and the efficacy of paclitaxel nanosuspensions (Paclitaxel-NS).

Results: A stable paclitaxel nanosuspension was prepared and coated with various excipients. Studies in mice showed that the nanosuspension was well-tolerated and at least as effective as the IV Taxol control in prolonging mouse survival in a head and neck cancer model as well as an ovarian cancer model with a lower overall drug dose than the traditional IV administration route.

Conclusions: The paclitaxel nanosuspension is suitable for cellular uptake. The nanosuspension was effective in prolonging life in two separate xenograft orthotopic murine cancer models through two separate routes of administration.     

Effects of α2-receptors

Summary Clonidine has a dual action on naloxone-precipitated morphine withdrawal symptoms in rats: a suppressive action on body shakes and body weight loss and a potentiating action on jumping and aggression.It has been suggested that this potentiating, excitatory action is mediated by ₁-receptors. More specific ₂-agonists therefore should have a less excitatory effect on the latter symptoms. This hypothesis has been studied in rats dependent on morphine. Withdrawal was precipitated using naloxone. Prior to naloxone the ₂-agonists clonidine, guanfacine, azepexole, BHT-920, UK 14304 or the centrally acting ₁-agonist ST 587 were administered. All ₂-agonists but not the ₁-agonist potentiated the jumping and decreased body shakes and body weight loss.The effects of clonidine and azepexole were characterized pharmacologically using the -antagonists yohimbine and prazosin. Jumping potentiated by clonidine was antagonized by yohimbine whereas prazosin had no effect. Azepexole induced jumping was decreased by yohimbine both with respect to incidence and frequency, whereas prazosin only lowered the frequency. The suppressive actions of clonidine and azepexole on body shakes were reversed by yohimbine and not by prazosin. The data indicate that the potentiation of jumping by ₂-agonists as well as the suppression of body shakes in morphine withdrawal behaviour is mediated by ₂-receptors.     

Down-regulation of α2-adrenoceptor subtypes

To characterize further the α₂-adrenoceptor subtypes in terms of their regulation, monolayers of cells expressing either the α_2A (CHO-A2AR cells) or α_2C (OK cells) subtype were preincubated with norepinephrine for various times and the extent of receptor down-regulation was assessed. Exposure to 30 μM norepinephrine caused a similar time course and extent of down-regulation (approximately 50%) in both cells lines. The extent of down-regulation caused by 0.3 μM norepinephrine in OK cells was similar to that with 30 μM norepinephrine in CHO-A2AR cells, although the time course was somewhat slower. Reversal of the down-regulation of the α₂-adrenoceptor caused by 30 μM norepinephrine was more rapid in the CHO-A2AR than in the OK cell. With 0.3 μM norepinephrine, reversal of down-regulation of the α₂-adrenoceptor in the OK cell was slightly faster than that of the CHO-A2AR cell with 30 μM norepinephrine. These data indicate that although norepinephrine is more potent in causing down-regulation of the α_2C (OK cells) as compared to the α_2A subtype (CHO-A2AR cells), the time courses for down-regulation and its reversal are similar for the two subtypes.     

Anti-implantation activity of 2 derivatives of o-hydroxy naphthaquinones in rats

AIM:To search for female contraceptive agents. METHODS: 2-Hydroxy-3-methyl-1, 4-naphthoquinone monosemicarbazone ( HMNQS ) and 2-hydroxy-1, 4-naphthoquinone monothiosemicarbazone ( HNQTS ) were screened for anti-implantation activity in rats. RESULTS: Both compounds showed a dose-dependent activity, and HNQTS was more potent. An 100 % anti-implantation activity was observed with HNQTS 150 mg kg-1 ig . Its LD50 was found to be >2g kg-1 ig in mice. CONCLUSION: HNQTS was more potent than HMNQS for anti-implantation activity in rats.     

Synergy Between 3′Azido-3′deoxythymidine and Paclitaxel in Human Pharynx FaDu Cells

Purpose. We recently demonstrated simultaneous targeting of telomere and telomerase as a novel cancer therapeutic approach, and that telomerase inhibitors such as 3azido-3deoxythymidine (AZT) significantly enhanced the antitumor activity of paclitaxel, which causes telomere erosion, in telomerase-positive human pharynx FaDu tumors in vitro and in vivo (1). The present study evaluated the synergy between AZT and paclitaxel to identify optimal combinations for future clinical evaluation. Methods. FaDu cells were incubated with or without AZT for 24 h and then treated with AZT with or without paclitaxel for an additional 48 h. Under these conditions, single agent paclitaxel produced a 60% maximum reduction of cell number (IC₅₀ was 7.3 nM), and single agent AZT produced a 97% reduction (IC₅₀ was 5.6 M). Synergy was evaluated using fixed-concentration and fixed-ratio methods, and data were analyzed by the combination index method. Results. The results indicate a concentration-dependent synergy between the two drugs; the synergy was higher for combinations containing greater paclitaxel-to-AZT concentration ratios and increased with the level of drug effect. For example, in combinations containing 1 M AZT, synergy was 1.3-fold at the 20% effect level and 3.1-fold at the 60% effect level. Because the major antitumor activity, determined by comparing the posttreatment cell number to the pretreatment cell number, was antiproliferation at the 20% effect level and cell kill at the 60% effect level, our results suggest that AZT mainly enhances the cell kill effect of paclitaxel. Conclusion. In summary, the present study demonstrates a synergistic interaction between paclitaxel and AZT and supports a combination using a low and nontoxic AZT dose in combination with a therapeutically active dose of paclitaxel.     

Analysis of the 2×2 crossover design with subsampling

Subsampling can be used in experimental design to investigate extraneous sources of variability. One useful strategy is to make independent replicate measurements of the response variate. This can be achieved in clinical studies, for example,by dividing a blood or urine specimen from each of a sample of subjects into aliquots and processing these through a chemistry laboratory in such a way that the replicate determinations are independent. This procedure can be used to increase design efficiency. This paper addresses considerations in the design and analysis of the 2×2 crossover plan with this type of subsampling.