Drug distribution and a pulmonary adverse effect of intraperitoneally administered doxorubicin niosomes in the mouse

Microniosomes for concurrent doxorubicin and iron oxide nanoparticles loading; preparation, characterization and cytotoxicity studies

The current work deals with developing a suitable drug delivery system of doxorubicin (DOX) for intraperitoneal chemotherapy using niosomes through formulating non-ionic surfactants consisting of Brij™ 52, span™ 60 and Solulan™ C24. Entrapping the magnetite nanoparticles in the hydrophilic parts of niosomes was accompanied with high-efficient DOX loading by the current novel remote-loading method. Cytotoxicity of the prepared formulations was evaluated in vitro against A549 and PC-12 cell lines using the colorimetric WST-1 assay test. The obtained results revealed that, the cytotoxicity of DOX increased up to 22% especially on A549 cells by the current delivery system.

Development of PIK-75 nanosuspension formulation with enhanced delivery efficiency and cytotoxicity for targeted anti-cancer therapy

PIK-75 is a phosphatidylinositol 3-kinase (PI3K) inhibitor that shows selectivity toward p110-α over the other PI3K class Ia isoforms p110-β and p110-δ, but it lacks solubility, stability and other kinase selectivity. The purpose of this study was to develop folate-targeted PIK-75 nanosuspension for tumor targeted delivery and to improve therapeutic efficacy in human ovarian cancer model. High pressure homogenization was used to prepare the non-targeted and targeted PIK-75 nanosuspensions which were characterized for size, zeta potential, entrapment efficiency, morphology, saturation solubility and dissolution velocity. In vitro analysis of drug uptake, cell viability and cell survival was conducted in SKOV-3 cells. Drug pharmacokinetics and pAkt expression were determined in SKOV-3 tumor bearing mice. PIK-75 nanosuspensions showed an improvement in dissolution velocity and an 11-fold increase in saturation solubility over pre-milled PIK-75. In vitro studies in SKOV-3 cells indicated a 2-fold improvement in drug uptake and 0.4-fold decrease in IC50 value of PIK-75 following treatment with targeted nanosuspension compared to non-targeted nanosuspension. The improvement in cytotoxicity was attributed to an increase in caspase 3/7 and hROS activity. In vivo studies indicated a 5-10-fold increased PIK-75 accumulation in the tumor with both the nanosuspension formulations compared to PIK-75 suspension. The targeted nanosuspension showed an enhanced downregulation of pAkt compared to non-targeted formulation system. These results illustrate the opportunity to formulate PIK-75 as a targeted nanosuspension to enhance uptake and cytotoxicity of the drug in tumor.

Effect of charged and non-ionic membrane additives on physicochemical properties and stability of niosomes

The aim of this study was to investigate an influence of different types of membrane additives including negative charge (dicetylphosphate, DCP), positive charge (stearylamine, STR) and non-ionic molecule (cholesteryl poly-24-oxyethylene ether, SC24) on the physicochemical properties of drug-free and drug-loaded niosomes. Salicylic acid having different proportions of ionized and unionized species at different pH was selected as a model drug. The niosomes were composed of 1:1 mole ratio of Span 60: cholesterol as vesicle forming agents. The results show that incorporation of salicylic acid to the niosomes did not affect zeta potential values; however, addition of the membrane additives changed the zeta potential depending on the type of the additives. Transmission electron microscopy revealed that niosomes had unilamellar structure. The particle sizes of all developed niosomes were between 217 to 360 nm. The entrapment efficiency (%E.E.) of all salicylic acid niosomes at pH 3 was higher than that of niosomes at pH 5, indicating that salicylic acid in unionized form was preferably incorporated in niosomes. Furthermore, the positively charged niosomes showed the highest %E.E. of salicylic acid owing to electrostatic attraction between STR and salicylic acid. After 3 months of storage at 4 degrees C, the particle size of the niosomes remained in the nanosize range except for DCP salicylic acid niosomes at pH 3 whose size increased due to an instability of DCP at low pH. In addition, all niosomes showed no leakage of the salicylic acid after 3 months of storage indicating the good stability.

PEGylated synthetic surfactant vesicles (Niosomes): novel carriers for oligonucleotides

Polyethylene glycol (PEG) modified cationic niosomes were used to improve the stability and cellular delivery of oligonucleotides (OND). PEGylated cationic niosomes, composed of DC-Chol, PEG2000-DSPE and the non-ionic surfactant-Span, offer some advantages as gene carriers. Complexes of PEGylated cationic niosomes and OND showed a neutral zeta potential with particle size about 300 nm. PEG-modification significantly decreased the binding of serum protein and prevented particle aggregation in serum. The loaded nuclear acid drug exhibited increased resistance to serum nuclease. Compared with cationic niosomes, the PEGylated niosomes showed a higher efficiency of OND cellular uptake in serum. Therefore, in terms of their stable physiochemical properties in storage and physiological environment, as well as low-cost and widely available materials, PEGylated cationic niosomes are promising drug delivery systems for improved OND potency in vivo.

The activity of doxorubicin niosomes against an ovarian cancer cell line and three in vivo mouse tumour models

Demonstration of the improved doxorubicin pharmacokinetics and tumoricidal activity, after a single intravenous dose of 10mg kg-1 doxorubicin sorbitan monostearate (Span 60) based niosomes in the mouse adenocarcinoma (MAC) tumour model (Uchegbu et al., 1995) preceded the present study in which the activity of doxorubicin C16G2 (a hexadecyl diglycerol ether) based niosomes was evaluated against naive and established MAC tumour models. C16G2 niosomes were equiactive with doxorubicin solution. It is concluded that while in some tumour models, niosomal formulations demonstrate some advantages over the free drug, caution is advocated in the extrapolation of these results. The activity of doxorubicin C16G2 and Span 60 niosomes was also studied against a human ovarian cancer cell line and its doxorubicin resistant subline. There was a slight reduction in the IC50 against the resistant cell line when the drug was encapsulated in Span 60 niosomes in comparison to the drug in solution. Taking into account the in-vitro release characteristics of the various niosomal formulations, it is concluded that the use of niosomal formulations against multidrug resistance shows sufficiently encouraging results to warrant further study.

Distribution, metabolism and tumoricidal activity of doxorubicin administered in sorbitan monostearate (Span 60) niosomes in the mouse

PURPOSE

Encapsulation of doxorubicin in niosomes was sought as a route to tumour targeting and improved tumoricidal through the alteration of doxorubicin pharmacokinetics and metabolism.

METHODS

Doxorubicin niosomes (10 mg kg-1 doxorubicin) prepared from sorbitan monostearate (Span 60), cholesterol and choleth-24 (a 24 oxyethylene cholesteryl ether) in the molar ratio 45:45:10 were administered intravenously to female NMRI mice bearing the MAC 15A subcutaneously implanted tumour. Plasma doxorubicin was fractionated by gel filtration and quantified by HPLC with fluorometric detection as niosome-associated doxorubicin and released doxorubicin. Tumoricidal activity of the formulation was assessed by the intravenous injection of 5 mg kg-1 and 10 mg kg-1 doxorubicin niosomes to male NMRI mice bearing a 6 day old MAC 15A tumour.

RESULTS

At least 90% of the plasma doxorubicin was associated with the niosome fraction 4 h after dosing, and 50% was still associated after 24 h. The clearance of doxorubicin released from the niosomes was about 10 fold greater than the clearance of niosomal doxorubicin (176.5 mL h-1 and 16.2 mL h-1, respectively). The area under the plasma level-time curve increased 6 fold when doxorubicin was administered in niosomes, compared to doxorubicin solution (66.0 micrograms.h mL-1 and 10.3 micrograms. h mL-1, respectively). The area under the tumour level time curve was increased by over 50% by the administration of doxorubicin in niosomes when compared to the drug administered in solution (58.6 micrograms.h mL-1 and 34.3 micrograms.h mL-1, respectively). There was no statistically significant difference between levels of the drug in the heart when niosomal doxorubicin or doxorubicin solution were administered. Doxorubicin metabolites, namely doxorubicinol and the aglycones doxorubicinone, doxorubicinolone and 7-deoxydoxorubicinone, were found associated with the niosomes in the plasma, possibly due to their adsorption to the vesicle surface once formed outside the niosome. Overall metabolite levels in the liver were increased when doxorubicin niosomes were administered compared to the drug in solution. A 5 mg kg-1 injection of doxorubicin niosomes produced a terminal mean tumour weight that was similar to that obtained from animals administered 10 mg kg-1 doxorubicin solution.

CONCLUSIONS

Modest tumour targeting was achieved by the delivery of doxorubicin in sorbitan monostearate niosomes, increasing the tumour to heart AUC0-24 ratio from 0.27 to 0.36 and a doubling of tumoricidal activity. The overall level of doxorubicin metabolites was also increased.