Antitumoral activity of camptothecin-loaded nanoparticles in 9L rat glioma model

Solubilisation of camptothecin by nonionic surfactants and alkyldimethylamine oxides

The solubilisation of poorly soluble antineoplastic drug camptothecin by nonionic surfactants (polysorbates and octylphenol ethoxylates) and alkyldimethylamine oxide surfactants with the alkyl chain length 8 to 16 carbon atoms was investigated. The hydrophobicity of the solubilising agent turned out to be the primary structural parameter controlling the solubility efficiency of camptothecin in an aqueous solution. The quantitative parameter of solubilisation (drug loading coefficient) provided values in the range of 0.1–1.2% and 0.1–1.0% for alkyldimethylamine oxides and nonionic surfactants, respectively. The decreasing number of oxyethylene units and the extension of the hydrophobic part of nonionic surfactant molecule resulted in the increase of camptothecin solubility. From the dynamic light scattering measurements, the hydrodynamic diameter values of camptothecin-loaded alkyldimethylamine oxide and nonionic micelles were found in the range of 4–42 nm and 5–120 nm, respectively. The experimental values confirmed the increase in micellar size with the increasing alkyl chain length. The values of the packing parameter of camptothecin-loaded dodecyldimethylamine oxide micelles indicate their spherical shape at all the investigated surfactant concentrations. A simple computer model of camptothecin-loaded dodecyldimethylamine oxide micelle provided the diameter of the structure cross section which is consistent with the experimental values.

Poly ɛ-caprolactone nanoparticles loaded with Uncaria tomentosa extract: preparation, characterization, and optimization using the Box-Behnken design

PURPOSE

The aim of this research was to develop and optimize a process for obtaining poly ɛ-caprolactone (PCL) nanoparticles loaded with Uncaria tomentosa (UT) extract.

METHODS

Nanoparticles were produced by the oil-in-water emulsion solvent evaporation method. Preliminary experiments determined the initial conditions of the organic phase (OP) and of the aqueous phase (AP) that would be utilized for this study. Ultimately, a three-factor three-level Box-Behnken design (BBD) was employed during the optimization process. PCL and polyvinyl alcohol (PVA) concentrations (X(1) and X(2), respectively) and the AP/OP volume ratio (X(3)) were the independent variables studied, while entrapment efficiency (Y(1)), particle mean diameter (Y(2)), polydispersity (Y(3)), and zeta potential (Y(4)) served as the evaluated responses.

RESULTS

PRELIMINARY EXPERIMENTS REVEALED THAT THE OPTIMAL INITIAL CONDITIONS FOR THE PREPARATION OF NANOPARTICLES WERE AS FOLLOWS: OP composed of 5 mL ethyl acetate/acetone (3/2) mixture containing UT extract and PCL, and an AP of buffered PVA (pH 7.5) solution. Statistical analysis of the BBD results indicated that all of the studied factors had significant effects on the responses Y(1), Y(2), and Y(4,) and these effects are closely described or fitted by regression equations. Based on the obtained models and the selected desirability function, the nanoparticles were optimized to maximize Y(1) and minimize Y(2). These optimal conditions were achieved using 3% (w/v) PCL, 1% (w/v) PVA, and an AP/OP ratio of 1.7, with predicted values of 89.1% for Y(1) and 280 nm for Y(2). Another batch was produced under the same optimal conditions. The entrapment efficiency of this new batch was measured at 81.6% (Y(1)) and the particles had a mean size of 247 nm (Y(2)) and a polydispersity index of 0.062 (Y(3)).

CONCLUSION

This investigation obtained UT-loaded nanoparticle formulations with desired characteristics. The BBD approach was a useful tool for nanoparticle development and optimization, and thus should be useful especially in the realm of phytotherapeutics, in which varied compositions may be assessed in quantitative and qualitative terms.

Brain delivery of camptothecin by means of solid lipid nanoparticles: formulation design, in vitro and in vivo studies

For the purpose of brain delivery upon intravenous injection, formulations of camptothecin-loaded solid lipid nanoparticles (SLN), prepared by hot high pressure homogenisation, were designed. Incorporation of camptothecin in the hydrophobic and acidic environment of SLN matrix was chosen to stabilise the lactone ring, which is essential for its antitumour activity, and for avoiding premature loss of drug on the way to target camptothecin to the brain. A multivariate approach was used to assess the influence of the qualitative and quantitative composition on the physicochemical properties of camptothecin-loaded SLN in comparison to plain SLN. Mean particle sizes of ≤200 nm, homogenous size distributions and high encapsulation efficiencies (>90%) were achieved for the most suitable formulations. In vitro release studies in plasma, showed a prolonged release profile of camptothecin from SLN, confirming the physical stability of the particles under physiological pH. A higher affinity of the SLN to the porcine brain capillary endothelial cells (BCEC) was shown in comparison to macrophages. MTT studies in BCEC revealed a moderate decrease in the cell viability of camptothecin, when incorporated in SLN compared to free camptothecin in solution. In vivo studies in rats showed that fluorescently labelled SLN were detected in the brain after i.v. administration. This study indicates that the camptothecin-loaded SLN are a promising drug brain delivery system worth to explore further for brain tumour therapy.

Molecular buckets: cyclodextrins for oral cancer therapy

The oral route is preferred by patients for drug administration due to its convenience, resulting in improved compliance. Unfortunately, for a number of drugs (e.g., anticancer drugs), this route of administration remains a challenge. Oral chemotherapy may be an attractive option and especially appropriate for chronic treatment of cancer. However, this route of administration is particularly complicated for the administration of anticancer drugs ascribed to Class IV of the Biopharmaceutical Classification System. This group of compounds is characterized by low aqueous solubility and low intestinal permeability. This review focuses on the use of cyclodextrins alone or in combination with bioadhesive nanoparticles for oral delivery of drugs. The state-of-the-art technology and challenges in this area is also discussed.

Development and validation of a simple reversed-phase HPLC method for the determination of camptothecin in animal organs following administration in solid lipid nanoparticles

A simple, sensitive and specific high-performance liquid chromatography (HPLC) assay for the quantification of camptothecin (CPT), a potent anticancer candidate, incorporated into solid lipid nanoparticles (SLN) in several rat organs (brain, heart, kidneys liver, lung, spleen) and serum was developed and validated. The sample pre-treatment involved organs homogenisation followed by CPT extraction. The samples were injected onto an analytical reversed-phase (RP) Mediterranea™ Sea18 column maintained at 30°C. The chromatographic separation was achieved by gradient elution consisting of triethyamine buffer pH 5.5 and acetonitrile at a flow rate of 1.2 mL/min in 16 min of run time and retention time of 9.8 min (lactone). Fluorescence detection was used at the excitation and emission of 360 and 440 nm, respectively. The calibration curves in the different organs, serum and in PB3 were linear (r(2)>0.9999) over CPT concentrations ranging from 1 to 200 ng/mL or 0.5 to 200 ng/mL (n=6), respectively. The method was shown to be specific, accurate (between 94.4±4.5% and 108.9±0.6%) and precise at the intra-day and inter-day levels as reflected by the coefficient of variation (CV<6.3%) at three different concentrations (10, 50 and 100 ng/mL) in all matrices. Stability studies showed that CPT was stable in all matrices after 24h of incubation at room temperature (RT), after 24 h in the autosampler or after three freeze/thaw cycles. The mean recoveries of CPT in suspension, loaded into SLN and in a physical mixture with SLN at three concentrations of 10, 50 and 200 ng/mL were higher than 86.4%. The detection limit (DL) was ≤0.2 ng/mL and the quantification limit (QL) was ≤0.5 ng/mL. The method developed is reliable, precise and accurate and can be used in the determination of CPT amount in rat organ samples after i.v. administration of CPT in suspension, in physical mixture with SLN and incorporated in SLN.

Nanoparticle delivery of natural products in the prevention and treatment of cancers: current status and future prospects

The advent of nanotechnology has had a revolutionary impact on many aspects of 21^st century life. Nanotechnology has provided an opportunity to explore new avenues that conventional technologies have been unable to make an impact on for diagnosis, prevention, and therapy of different diseases, and of cancer in particular. Entities in nanometer sizes are excellent platforms to incorporate various drugs or active materials that can be delivered effectively to the desired action site without compromising the activity of the incorporated drug or material. In particular, nanotechnology entities can be used to deliver conventional natural products that have poor solubility or a short half life. Conventional natural products used with entities in nanometer sizes enable us to solve many of the inherent problems (stability, solubility, toxicity) associated with natural products, and also provide a platform for targeted delivery to tumor sites. We recently introduced the novel concept of using nanotechnology for enhancing the outcome of chemoprevention, which we called ‘nanochemoprevention’. This idea was subsequently exploited by several laboratories worldwide and has now become an advancing field in chemoprevention research. This review examines some of the applications of nanotechnology for cancer prevention and therapy using natural products.