Epidermal growth factor receptor-targeted peptide conjugated phospholipid micelles for doxorubicin delivery.

Specific targeting of tumor cells to achieve higher drug levels in tumor tissue and to overcome side effects is the major goal in cancer chemotherapy. In this study, we used a tumor targeting peptide, GE11, to conjugate onto the surface of doxorubicin encapsulated phospholipid micelles. The GE11 peptide triggered specific binding to epidermal growth factor receptor (EGFR), leading to enhanced cellular uptake and cytotoxicity in vitro and highly accumulation in the tumors in vivo. The results indicated that GE11 conjugated phospholipid micelles should have potential applications in cancer therapy.

Chlorambucil gemcitabine conjugate nanomedicine for cancer therapy.

Self-assembly of anticancer small molecules into nanostructures may represent an attractive approach to improve the treatment of experimental solid tumors. As a proof of concept, we designed and synthesized the conjugate prodrug of hydrophilic gemcitabine by its covalent coupling to hydrophobic chlorambucil via a hydrolyzable ester linkage. The resulting amphiphilic conjugates self-assembled into nanoparticles in water and exhibited significant anticancer activity in vitro against a variety of human cancer cells. In vivo anticancer activity of these nanoparticles has been tested on subcutaneous grafted SMMC-7721 hepatocellular carcinoma model. Such chlorambucil gemcitabine conjugate nanomedicine should have potential applications in cancer therapy.

Design and biological activity of epidermal growth factor receptor-targeted peptide doxorubicin conjugate.

The nonspecific toxicity of anticancer drug doxorubicin (DOX) toward both tumor and normal cells can result in serious side effects, thereby limiting its clinical applications. In this wok, epidermal growth factor receptor (EGFR) antagonist peptide GE11 was introduced into DOX structure via a disulfide bond which can be cleaved by reduced glutathione (GSH). We have investigated the intracellular delivery and in vitro cytotoxicity of GE11-DOX conjugate and free DOX in high (SMMC-7721) and low (MCF-7) EGFR expressing cancer cell models. GE11-DOX accumulated at higher levels in SMMC-7721 cells than in MCF-7 cells, while the cellular uptake of free DOX was almost the same in both cells. Furthermore, pretreating with anti-EGFR monoclonal antibody reduced intracellular accumulation of GE11-DOX in SMMC-7721, indicating the involvement of EGFR pathway in the transport of conjugate. Our results suggest that GE11-DOX conjugate has the potential to be a therapeutic agent for treating EGFR overexpressing tumor.

Effect of molecular weight of PGG-paclitaxel conjugates on in vitro and in vivo efficacy.

Polymeric prodrugs are one of the most promising chemotherapeutic agent delivery approaches, displaying unique drug release profiles, serum stability, formulation flexibility, and reduced drug resistance. One of the most important aspects of a polymeric prodrug, albeit a less-extensively studied one, is the polymer's molecular weight, which affects particle formation, drug release and PK/PD profiles, drug stability, and cell uptake; these factors in turn affect the prodrug's maximum tolerated dose and anticancer efficacy. Poly(L-γ-glutamylglutamine) (PGG) is a linear polymer designed to improve the therapeutic index of attached drugs. In this study we selected poly(L-γ-glutamylglutamine)-paclitaxel (PGG­PTX), as a model system for the methodical investigation into the effects of the poly(L-γ-glutamylglutamine) backbone molecular weight on its pharmacological performance. The polymeric prodrug was characterized by NMR, DLS and GPC-MALS, and its anticancer activity in vitro and in vivo was assessed. Herein we present data which provide valuable insight into improving anticancer polymer-based prodrug design and development.

Synthesis, characterization, and in vivo efficacy evaluation of PGG-docetaxel conjugate for potential cancer chemotherapy.

AIM: This work is intended to develop and evaluate a biopolymeric poly(L-γ-glutamylglutamine) (PGG)-docetaxel (DTX) conjugate that can spontaneously self-assemble in aqueous solutions to become nanoparticles. METHODS: DTX was covalently attached to hydrophilic PGG by direct esterification, and the conjugate was characterized by proton nuclear magnetic resonance spectroscopy, molecular weight gel permeation chromatography, solubility, size distribution and morphology, and hemolysis. Conjugated DTX was found to have 2000 times improved water solubility compared with free DTX. Dynamic light scattering, transmission electron microscopy, and atomic force microscopy revealed the particle size, distribution and morphology of the PGG-DTX conjugate. In addition, the conjugate was further tested for in vitro cytotoxicity and in vivo antitumor efficacy on the human non-small cell lung cancer cell line NCI-H460. RESULTS: Conjugated DTX was found to have 2000 times improved water solubility compared with free DTX. The conjugate formed nanoparticles with an average diameter of 30 nm in spherical shape and unimodal particle size distribution. The conjugate exhibited about 2% hemolysis at 10 mg/mL, compared with 56% for Tween 80(®) at 0.4 mg/mL, and 33% for Cremophor EL(®) at 10 mg/mL. In addition, the conjugate was further tested for in vitro cytotoxicity and in vivo antitumor efficacy on the human non-small cell lung cancer cell line NCI-H460. As expected, conjugated DTX exhibited lower cytotoxicity compared to that of free DTX, in concentration-dependent manner. However, PGG-DTX showed better antitumor activity in NCI-H460 lung cancer-bearing mice with minimal weight loss compared to that of free DTX. CONCLUSION: The PGG-DTX conjugate may be considered as an attractive and promising polymeric DTX conjugate for non-small cell lung cancer treatment.

Physicochemical properties and biocompatibility of a polymer-paclitaxel conjugate for cancer treatment.

BACKGROUND: Poly(L-γ-glutamylglutamine) paclitaxel (PGG-PTX) conjugate is a non-diblock polymeric drug nanoparticle intended to improve the therapeutic index of paclitaxel. The purpose of the present study was to elucidate further the physicochemical properties of PGG-PTX in order to proceed with its clinical development. METHODS AND RESULTS: PGG-PTX was designed by integration of a hydrophobic paclitaxel conjugate through an added hydrophilic glutamic acid onto poly(L-glutamic acid). The addition of a flexible glutamic linker between PGA and paclitaxel resulted in spontaneous self-assembly of a PGG-PTX conjugate into nanoparticles. The PGG-PTX conjugate was stable as a lyophilized solid form. An in vitro viability experiment showed that PGG-PTX was effective after a longer incubation period, the same trend as Taxol. In vitro studies using NCI-H460 and B16F0 cancer cells demonstrated significantly high cellular uptake after 30 minutes of incubation. The in vivo biocompatibility of PGG-PTX conjugate was evaluated in the NCI-H460 tumor model, the assessment of tissue seemed to be normal after 21 days of treatment. CONCLUSION: These results are encouraging for further development of non-block polymeric paclitaxel nanoparticles for treatment of cancer.

Novel free paclitaxel-loaded poly(L-γ-glutamylglutamine)-paclitaxel nanoparticles.

The purpose of this study was to develop a novel formulation of paclitaxel (PTX) that would improve its therapeutic index. Here, we combined a concept of polymer-PTX drug conjugate with a concept of polymeric micelle drug delivery to form novel free PTX-loaded poly(L-γ-glutamylglutamine) (PGG)-PTX conjugate nanoparticles. The significance of this drug formulation emphasizes the simplicity, novelty, and flexibility of the method of forming nanoparticles that contain free PTX and conjugated PTX in the same drug delivery system. The results of effectively inhibiting tumor growth in mouse models demonstrated the feasibility of the nanoparticle formulation. The versatility and potential of this dual PTX drug delivery system can be explored with different drugs for different indications. Novel and simple formulations of PTX-loaded PGG-PTX nanoparticles could have important implications in translational medicines.

Clinically relevant anticancer polymer Paclitaxel therapeutics.

The concept of utilizing polymers in drug delivery has been extensively explored for improving the therapeutic index of small molecule drugs. In general, polymers can be used as polymer-drug conjugates or polymeric micelles. Each unique application mandates its own chemistry and controlled release of active drugs. Each polymer exhibits its own intrinsic issues providing the advantage of flexibility. However, none have as yet been approved by the U.S. Food and Drug Administration. General aspects of polymer and nano-particle therapeutics have been reviewed. Here we focus this review on specific clinically relevant anticancer polymer paclitaxel therapeutics. We emphasize their chemistry and formulation, in vitro activity on some human cancer cell lines, plasma pharmacokinetics and tumor accumulation, in vivo efficacy, and clinical outcomes. Furthermore, we include a short review of our recent developments of a novel poly(L-g-glutamylglutamine)-paclitaxel nano-conjugate (PGG-PTX). PGG-PTX has its own unique property of forming nano-particles. It has also been shown to possess a favorable profile of pharmacokinetics and to exhibit efficacious potency. This review might shed light on designing new and better polymer paclitaxel therapeutics for potential anticancer applications in the clinic.

Synthesis and application of poly(ethylene glycol)-cholesterol (Chol-PEGm) conjugates in physicochemical characterization of nonionic surfactant vesicles.

Vesicles possessing poly(ethylene glycol) (PEG) chains on their surface have been described as a blood-persistent drug delivery system with potential applications for intravenous drug administration. In this research with different molecular weights (400-10,000g/mol) of PEG, a series of Chol-PEG(m) conjugates were generated by the DCC (N,N'-dicyclohexylcarbodiimide, DCC)/(4-dimethylaminopyridine, 4-DMAP) esterification method, and confirmed by FT-IR and (1)H NMR spectrum. Then their properties in aqueous solution were studied by electron microscopy images, associative behavioral and systematic tensiometric studies over a wide concentration range. In order to elucidate the application of this Chol-PEG(m) in vesicles, conventional nonionic surfactant vesicles (niosomes) composed of span 60 and cholesterol were prepared and the influence of various hydrophilic chains of the Chol-PEG(m) conjugates was investigated. Results indicated that all the niosomes prepared, with or without Chol-PEG(m) composition were similar in micrograph with diameter between 120 nm and 180 nm. The fixed aqueous layer thickness (FALT) around niosomes increased as Chol-PEG(m) chain length increase, particularly in the Chol-PEG(10,000) modified niosomes with 9.33+/-0.67 nm. In vitro release experiments indicated that release rate of nimodipine from Chol-PEG(m) modified niosomes was enhanced. Chol-PEG(m) modified niosomes showed greater accumulative release than that of plain niosomes over a period of 24 h. These studies have shed some light on the suitability of Chol-PEG(m) containing niosome preparation.

[A kind of improved operative correction of severe inverted nipples].

OBJECTIVE: To introduce a kind of improved operative method for correction of severe inverted nipples. METHODS: Sixteen patients (aged 28-38 years) with 31 inborn inverted nipples were operated with the improved method from January 2002 to March 2005. The nipple was incised horizontally through the middle, the fibrotic band was released, and the tissue below the nipple was contracted. Then the defective space with mammary gland flap. Finally, a Z-shaped suture was employed at each base of nipple. RESULTS: The shapes of these nipples were satisfactory. No infection and necrosis of the nipples occurred. The follow-up showed that the results were perfect in the sensory and elective functions of nipples. All the corrected nipples did not have recurrence except one nipple. The scars in the local site were limited and inconspicuous. CONCLUSION: Severe inverted nipples can be corrected effectively by the combined improved incisions and Z-shaped sutures. This method is suitable for the female patients with no requirement for feeding.

Preparation, characterization, and pharmacokinetics of sterically stabilized nimodipine-containing liposomes.

Nimodipine is a dihydropyridine calcium antagonist used in clinical trials in the treatment of ischemic damage in subarachnoid hemorrhage and commercially available as nimotop intravenous infusion solution and tablets. However, due to its poor solubility in water, intravenous administration depends on the use of the dehydrated alcohol to achieve a clinically relevant concentrated infusion solution while the low bioavailability of the nimotop tablets were far away from content. We have prepared a well-characterized novel lyophilized liposome-based nimodipine formulation that is sterile and easy-to-use. Of the several formulations examined, nimodipine-liposomes composed of ePC/CHOL 20:3 and co-surfactant poloxamer 188/sodium deoxycholate/ePC/3:0.3:5 were chosen for further studies. This composition was found to give more stable liposomes than other formulations. It gave 89.9% entrapment efficiency and particle size of 200 nm after lyophilization. The pharmacokinetic parameters following orally and intravenously administration to New Zealand rabbits were determined and compared with those of commercial nimodipine formulations. Encapsulation of nimodipine in liposomes produced marked differences over those of commercial preparations with an increased C(max), prolonged elimination half-life, and an increased value for AUC. The obtained values for mean residence time (MRT) indicated that nimodipine remains longer for liposomal formulation. Thus an optimum i.v. liposome formulation for nimodipine can be developed for an alternative to the commercial nimodipine preparations.

Deposition of insulin powders for inhalation in vitro and pharmacodynamic evaluation of absorption promoters in rats.

AIM: To prepare insulin powder for inhalation by spray-drying technology, determine the deposition of the insulin powder formulation in vitro and preliminarily investigate hypoglycemic response of the dry powder with/without absorption promoters. METHODS: The depositions of the insulin powder for inhalation were determined by the China Pharmacopoeia 2000 version addenda XH and hypoglycemic effects were evaluated by testing serum glucose with glucose oxidase-peroxidase (GOD-PAP) method. RESULTS: The depositions of the spray-dried insulin powder for inhalation were more than 40% under various humidity and their changes were not significant when air flow was no less than 18 L x min(-1). The coadministration of insulin with 8 mmol x L(-1)/dose sodium taurocholate [PA = 59.91%, Cnadir = (33 +/- 6) %] and 10 mmol x L(-1)/dose sodium deoxycholate [PA = 47.46% , Cnadir = (32 +/- 7)%] induced a significantly greater decline in blood glucose levels, while coadministration with 1% sodium caprylate, 1% sodium dodecyl sulfate, 250 microg/dose lecithin, 10 mmol x L(-1)/dose EDTA appeared to have no significant effect (P > 0.05). CONCLUSION: Insulin powder for inhalation was relatively stable under various humidity conditions and different flow current. The use of 8 mmol x L(-1)/dose sodium taurocholate and 10 mmol x L(-1)/dose sodium deoxycholate could be able to potentially improve the bioavailability of insulin by pulmonary route.