Design, synthesis and antitumor activity of aromatic urea-quinazolines.

Background: Gefitinib and sorafenib have been proved effective for the treatment of cancers in clinical practice for years. Materials & methods: We intended to integrate the structural features of gefitinib and sorafenib and construct structurally unique 7-aromatic ureido-4-anilinoquinazolines. Results: Most of the targets exhibited promising antitumor activities. 8u showed excellent antitumor activities against the three tested cell lines (IC50, 0.81-2.49 µM). The enzymatic, apoptosis assay of 8u were also performed to study their preliminary action of mechanism. Conclusion: 8u deserve further research as antitumor agents.

Enhancing siRNA-based cancer therapy using a new pH-responsive activatable cell-penetrating peptide-modified liposomal system.

As a potent therapeutic agent, small interfering RNA (siRNA) has been exploited to silence critical genes involved in tumor initiation and progression. However, development of a desirable delivery system is required to overcome the unfavorable properties of siRNA such as its high degradability, molecular size, and negative charge to help increase its accumulation in tumor tissues and promote efficient cellular uptake and endosomal/lysosomal escape of the nucleic acids. In this study, we developed a new activatable cell-penetrating peptide (ACPP) that is responsive to an acidic tumor microenvironment, which was then used to modify the surfaces of siRNA-loaded liposomes. The ACPP is composed of a cell-penetrating peptide (CPP), an acid-labile linker (hydrazone), and a polyanionic domain, including glutamic acid and histidine. In the systemic circulation (pH 7.4), the surface polycationic moieties of the CPP (polyarginine) are "shielded" by the intramolecular electrostatic interaction of the inhibitory domain. When exposed to a lower pH, a common property of solid tumors, the ACPP undergoes acid-catalyzed breakage at the hydrazone site, and the consequent protonation of histidine residues promotes detachment of the inhibitory peptide. Subsequently, the unshielded CPP would facilitate the cellular membrane penetration and efficient endosomal/lysosomal evasion of liposomal siRNA. A series of investigations demonstrated that once exposed to an acidic pH, the ACPP-modified liposomes showed elevated cellular uptake, downregulated expression of polo-like kinase 1, and augmented cell apoptosis. In addition, favorable siRNA avoidance of the endosome/lysosome was observed in both MCF-7 and A549 cells, followed by effective cytoplasmic release. In view of its acid sensitivity and therapeutic potency, this newly developed pH-responsive and ACPP-mediated liposome system represents a potential platform for siRNA-based cancer treatment.

[Activatable cell-penetrating peptides: a potential activatable modality for diseases diagnosis and therapy].

Cell-penetrating peptides are composed of positively-charged amino acids that can mediate molecules or nano-carriers across cell membranes. However, most of the known cell-penetrating peptides have no cell- or tissue-specificity, with affinity to almost all types of cells in internalization. The non-specificity of cell-penetrating peptides is a significant obstacle in the application to targeted delivery of imaging probes and therapeutic agents. Accordingly, many studies focused on selective switching of systemically-delivered inert cell-penetrating peptides into active forms in diseased tissues. Tsien groups introduced the concept of activatable cell-penetrating peptides in 2004. Subsequently, a growing number of similar delivery systems(molecular or nano-sized) have been documented, and the sensitive factors have included enzyme, lower p H, light and exogenous component. In this paper, we make an overview of the development of activatable delivery system in recent years.

[The application of enzyme-sensitive activatable cell-penetrating peptides to targeted delivery system].

Cell-penetrating peptides (CPPs) offer a non-selective and receptor-independent mode to promote cellular uptake. Although the non-specificity of CPP-mediated internalization allows this approach applicable to a wide range of tumor types potentially, their universality is a significant obstacle to their clinical utility for targeted delivery of cancer therapeutics and imaging agents. Accordingly, many reports have focused on selective switching of systemically delivered inert CPPs into their active form in lesions (tumor). In this review, our attention is mainly confined to such an enzyme-sensitive domain incorporated delivery system with activatable CPPs (ACPPs), which have displayed the exciting strength in balancing the CPPs' pros and cons, and potential in the treatment and diagnosis of some diseases.

PSA-responsive and PSMA-mediated multifunctional liposomes for targeted therapy of prostate cancer.

In the hormone-refractory stage of prostate cancer (PC), the expression of prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) often remains highly active. Accumulating studies have demonstrated that these two proteins are attractive targets for specific delivery of functional molecules to advanced PC, not merely as potential sensitive markers for PC detection. In this study, we constructed a dual-modified liposome that incorporated PSA-responsive and PSMA-mediated liposomes and potentially offers double selectivity for PC. The folate moiety binds quickly to PSMA-positive tumors, and the PSA-responsive moiety is cleaved by PSA that was enriched in tumor tissues. The activated liposomes (folate and cell-penetrating peptides dual-modifications) are subsequently taken up by the tumor cells via polyarginine's penetrating effects and receptor-mediated endocytosis. To corroborate these assumptions, a series of experiments were conducted, including PSA-responsive peptide hydrolysis kinetics, cellular uptake, internalization mechanism and escape from endosomes in PC-3 and/or 22Rv1 cells, biodistribution and antitumor activity of siRNA-loaded liposomes after systemic administration, gene silencing and cell apoptosis in vitro and in vivo. The results reveal that multivalent interactions play a key role in enhancing PC cell recognition and uptake while reducing nonspecific uptake. The dual-modified liposomes carrying small interfering RNA (siRNA) have significant advantages over the control liposomes, including single-modified (folate, CPP, PSA-responsive only) and non-modified liposomes. The dual-modified liposomes elevated cellular uptake, downregulated expression of polo-like kinase 1 (PLK-1) and augmented cell apoptosis in prostate tumor cells. The entry of the dual-modified liposomes into 22Rv1 cells occurred via multiple endocytic pathways, including clathrin-mediated endocytosis and macropinocytosis, followed by an effective endosomal escape of the entrapped siRNA into the cytoplasm. In vivo studies conducted on a 22Rv1 xenograft murine model demonstrated that the dual-modified liposomes demonstrated the maximized accumulation, retention and knockdown of PLK-1 in tumor cells, as well as the strongest inhibition of tumor growth and induction of tumor cell apoptosis. In terms of targeting capacity and therapeutic potency, the combination of a PSA-responsive and PSMA-mediated liposome presents a promising platform for therapy and diagnosis of PSMA/PSA-positive PC.

Pharmacodynamics and toxicity of vasoactive intestinal peptide for intranasal administration.

The aim of this work was to study the nasal route for the delivery of vasoactive intestinal peptide (VIP) to the brain and to evaluate the toxicity of VIP nasal spray. Mice were injected intracerebroventricularly with the aggregated Abeta25-35 to mimic Alzheimer's disease. Following administration, different groups of mice were treated over one week, and their spatial learning and memory capacities were evaluated by the Morris water maze test. The toxicity of VIP nasal spray was evaluated by examining the morphology of individual rat nasal mucosa cilia and the pathology of rat nasal mucosa. Rats receiving intranasal VIP (40 microg/ml) showed good spatial memory relative to the Abeta25-35 model group, but the escape latency did not show any statistically significant difference. Intranasal administration of VIP nasal spray (200 microg/ml) improved deficits in spatial memory to the point that test animals receiving intranasal VIP showed no statistically significant differences from the normal control group in escape latency. This indicated that the nasal spray method could increase the quantity of VIP entering the brain and protect the central nervous systems of mice. Toxicity evaluation showed that the preparation could cause minor irritation, which resolved spontaneously within a week at the end of treatment. In conclusion, VIP can be delivered successfully to the brain using the intranasal route.

[Optimization of a floating osmotic pump system of ambroxol hydrochloride using central composite design-response surface methodology and its pharmacokinetics in Beagle dogs].

This paper reported that a new type of floating osmotic pump of ambroxol hydrochloride was designed. Third method apparatus (Chinese Pharmacopeia 2010, appendix XD) was employed to simultaneously evaluate the release and floating behavior in vitro. The system was optimized using central composite design-response surface methodology. Similar factor (f2) between the release profile of self-made formulation and the target release profile was chosen as dependent factor. The amount of glucose (A, mg), pore former (B, %) and weight of coating (C, %) were employed as independent factors. Optimized formulation was: A (100.99 mg), B (1.70%), C (4.21%). The value of f2 (89.14) was higher than that of market capsules (69.02) and self-made tablets (72.15). It was showed that self-made capsules possessed character of zero-order release (r = 0.994 4) and drug release completely (>90%). It was showed in result of in vivo study that tmax and Cmax of self-made capsules were significantly lower than that of market capsules and self-made tablets. The correlation coefficient between the fraction of absorption in vivo and the release rate in vitro was 0.985 1, and relative bioequivalence of self-made capsules was 110.77%. Accordingly, self-made capsules displayed obviously characteristics of controlled release both in vivo and in vitro.

[Studies on preparation and dissolution test in vitro of sustained-release dropping pills of curcumin].

OBJECTIVE: To study the prescription and technique of sustained-release dropping pills of curcumin and inspect their release property in vitro. METHODS: The orthogonal test was used to screen the prescription and technique which were definited with the colligation evaluation of release and formation of dropping pills. RESULTS: The optimization of prescription and technique were as follows: stearic acid 70 mg, glycery monostearate 25 mg, solutol 6 mg, viscosity of cooling liquid was 100 mm2/s; the temperature of material liquid was 80 degrees C; the cooling temperature was 30 - 0 degrees C; the dropping speed was (21 +/- 2) dripping/min. The release behavior of sustained-release dropping pills of curcumin coincidented with Higuchi equation well and the character of sustained-release was transparent. CONCLUSIONS: The sustained-release dropping pills of curcumin have good property of sustained-release in vitro and their release behavior in vivo need to be inspected.

Studies of chitosan/Kollicoat SR 30D film-coated tablets for colonic drug delivery.

The aim of the study was to define in vitro and in vivo characteristics of chitosan/Kollicoat SR30D film-coated tablets of theophylline for colonic delivery. The tablet cores were coated to different film thicknesses with blends of Kollicoat SR30D and chitosan (2.5:1, 3.5:1, and 5:1, w/w). Swelling and drug release studies were carried out in simulated gastric fluid, simulated intestinal fluid and simulated colonic fluid, respectively. The mechanism of drug release was determined using the Korsmeyer-Peppas model. The in vivo degradation of the tablets was also studied in rats. The swelling behavior and drug release depended on the composition of the coating, as well as the ratio of Kollicoat SR30D to chitosan. The coating was susceptible to enzymatic action, and more accessible to bacterial enzymes than beta-glucosidase enzyme. The extent of swelling and digestion correlated with the amount of chitosan within the coating. The drug release data fit well into the Korsmeyer-Peppas equation, indicating that the drug release was controlled by polymer relaxation. The in vivo pharmacokinetic studies of the coated tablets showed delayed T(max), decreased C(max) and prolonged MRT. Chitosan/Kollicoat SR30D coated tablets could deliver the drug to the targeted site for local action.

Design and in vitro/in vivo evaluation of multi-layer film coated pellets for omeprazole.

The purpose of the study is to perform the in vitro and in vivo evaluation of multi-layer film coatings for omeprazole. The system consists of drug-layered or drug-containing core pellets coated with salt (sodium chloride and disodium hydrogen phosphate), hydroxypropyl methyl cellulose (HPMC), and enteric film-coating layer, respectively. The drug-layered core pellets were prepared by a coating layer of omeprazole on inert pellet cores in fluidized bed coater. An in vitro/in vivo gastro-resistance study was conducted, and a dissolution study was performed in pH 7.4 phosphate buffer for omeprazole release. The multi-layer coated pellets were stable in gastric pH conditions and upper gastrointestinal (GI) tract in rats. Salt layer improved the drug stability, and its coating levels had little influence on the dissolution profiles of omeprazole. The rate of drug release was significantly delayed by HPMC layer. The salt layer could function as a separated layer, and substitute part of the HPMC layer and decrease the coating levels of HPMC. The bioavailability (AUC) of the multi-layer coated drug-layered and drug-containing pellets was 3.48+/-0.86 and 2.97+/-0.57 microg*h/ml, respectively. The drug-layered pellets with multi-layer film coatings not only provided delayed and rapid release of omeprazole, but also could provide a good stable property for omeprazole. It was confirmed that rapid in vitro drug release rate resulted in better absorption.

Biphasic drug release: permeability and swelling of pectin/ethylcellulose films, and in vitro and in vivo correlation of film-coated pellets in dogs.

The major objectives of this study were i) to evaluate the permeability and swelling characteristics of isolated films prepared by mixing of pectin with ethylcellulose; and ii) to assess the absorption and in vitro/in vivo correlation (IVIVC) of 5-FU film-coated colon-targeted pellets in dogs. Free films were prepared by casting and solvent evaporation method. These free films were evaluated by swelling experiment and permeability to 5-FU in different media. Pectin/ethylcellulose films had suitable characteristics for colonic delivery; and when the addition of pectin was up to the ratio of 30%, the swelling and permeability of the mixed films was significantly increased in the simulated colonic fluid (SCF). Pharmacokinetic study in dogs gave Tmax/Cmax of 14 h/1.6 microg/ml and 16 h/1.7 microg/ml for total weight gain (TWG)-22% and 18% coated pellets, respectively. The plasma 5-FU levels of the TWG-22% and 18% coated pellets were maintained at a much lower level with a mean residence time (MRT) of 18-20 h, longer than 2.1 h for 5-FU uncoated pellets, confirming delayed absorption. There was no statistically significant difference in the area under the plasma concentration vs. times curve (AUC) values between the uncoated pellets and the coated pellets. Moreover, a good linear regression relationship was observed between the percent in vitro dissolution in SCF and the percent absorption or percent AUC. It was concluded that i) pectin within the mixed films were susceptible to colonic enzymes, and the film-coated pellets are potentially useful for colonic drug delivery; and ii) in vitro dissolution testing in SCF could be used to establish certain IVIVC for the colon-specific drug delivery systems activated by microflora.

Selective drug delivery to the colon using pectin-coated pellets.

A combination of ethylcellulose and pectin, when applied as a film coat, has a potential value as a colon-specific delivery system. Dispersions of pectin in ethylcellulose were used as the film former for coating of 5-aminosalicylic acid (5-ASA) pellet cores. Drug release behavior was assessed, in vitro, under simulating conditions in term of pH and time in vivo during transit to the colon. Negligible drug release occurred during first 5 h, when the coated pellets were in the simulated gastric and small intestinal conditions. After that, rat cecal contents were added into the pH 6.8 medium to simulate the in vivo condition where there is the digestion of bacteria in the colon. Drug release depended on the composition of the mixed film, as well as the ratio of ethylcellulose to pectin. Drug release profiles seemed to conform to the mechanism involving the osmotically driven release and formation of channels in the film caused by dissolution of pectin. Channel formation was, in most cases, activated by the presence of rat cecal contents, showing that the pectin in the mixed film was subjected to enzymic breakdown. In conclusion, pectin could be used as an additive in ethylcellulose films to control the release of colonic delivery system. In addition, the mechanism of the hydrophilic drug release from pellets coated with ethylcellulose aqueous dispersions containing an aqueous gel-forming polymer (pectin) is also discussed.

Study on colon-specific pectin/ethylcellulose film-coated 5-fluorouracil pellets in rats.

The purpose of the present study is to assess the biodistribution and pharmacokinetics of pectin/ethylcellulose film-coated and uncoated pellets containing 5-fluorouracil (5-FU) in rats. Both coated and uncoated pellets were orally administered to the rats at a dosage equivalent to 15mg/kg. 5-FU concentrations in different parts of the gastrointestinal (GI) tract and plasma were quantitatively analyzed using a high-performance liquid chromatography (HPLC) assay. 5-FU released from uncoated pellets mainly distributes in the upper GI tract, however, 5-FU released from coated pellets mainly distributes in the cecum and colon. In plasma, the observed mean C(max) from the coated pellets group (3.65+/-2.3microg/mL) was lower than that of the uncoated pellets group (23.54+/-2.9microg/mL). The AUC values obtained from the uncoated pellets and the coated pellets were 49.08+/-3.1 and 9.06+/-1.2microgh/mL, respectively. The relatively high local drug concentration with prolonged exposure time provides a potential to enhance anti-tumor efficacy with low systemic toxicity for the treatment of colon cancer.