Nanosizing of a drug/carrageenan complex to increase solubility and dissolution rate

Nanosizing for oral and parenteral drug delivery: a perspective on formulating poorly-water soluble compounds using wet media milling technology

A significant percentage of active pharmaceutical ingredients identified through discovery screening programs is poorly soluble in water. These molecules are often difficult to formulate using conventional approaches and are associated with innumerable formulation-related performance issues, e.g. poor bioavailability, lack of dose proportionality, slow onset of action and other attributes leading to poor patient compliance. In addition, for parenteral products, these molecules are generally administered with co-solvents and thus have many undesirable side effects. Wet media milling is one of the leading particle size reduction approaches that have been successfully used to formulate these problematic compounds. The approach is a water-based media milling process where micron-sized drug particles are shear-fractured into nanometer-sized particles. Nanoparticle dispersions are stable and typically have a mean diameter of less than 200 nm with 90% of the particles being less than 400 nm. The formulation consists only of water, drug and one or more GRAS excipients. Drug concentrations approaching 300-400mg/g can be targeted with the use of minimal amounts stabilizer. Typically, on average, the drug to stabilizer ratio on a weight basis ranges from 2:1 to 20:1. These liquid nanodispersions exhibit acceptable shelf-life and can be post-processed into various types of solid dosage forms. Nanoparticulate-based drug products have been shown to improve bioavailability and enhance drug exposure for oral and parenteral dosage forms. Suitable formulations for the most commonly used routes of administration can be identified with milligram quantities of drug substance providing the discovery scientist an alternate avenue for screening and identifying superior leads. In the last few years, formulating poorly water soluble compounds as nanosuspensions has evolved from a conception to a realization. The versatility and applicability of this drug delivery platform are just beginning to be realized.

Nanosuspensions of poorly soluble drugs: preparation and development by wet milling

Nanosizing techniques are important tools for improving the bioavailability of water insoluble drugs. Here, a rapid wet milling method was employed to prepare nanosuspensions: 4 types of stabilizers at 4 different concentrations were tested on 2 structurally different drug compounds: indomethacin and itraconazole. Photon correlation spectroscopy (PCS) results showed that the finest nanosuspensions were obtained when 80 wt% (to drug amount) pluronic F68 was the stabilizer for indomethacin and 60 wt% pluronic F127 for itraconazole. Compared to physical mixtures, dissolution rates of the nanosuspensions showed significant increases. The morphology of nanoparticles was observed by transmission electron microscopy (TEM). Crystalline state of the drugs before and after milling was confirmed using differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD). The physical and chemical stabilities of the nanosuspensions after storage for 2 months at room temperature and at 4°C were investigated using PCS, TEM and HPLC. No obvious changes in particle size and morphology and no chemical degradation of the drug ingredients were seen.

Development and in vitro evaluation of deacety mycoepoxydiene nanosuspension

Deacety mycoepoxydiene (DM), extracted from Phomopsis sp. A123 of thalassiomycetes, is a novel and potent anti-cancer agent. Due to its physicochemical characteristics, the drug, a poorly water-soluble weak acid, shows poor solubility and dissolution characteristics. To improve the solubility and dissolution, formulation of DM as nanosuspension has been performed in this study. Nanosuspensions were developed by high-pressure homogenization (HPH) (DissoCubes(®) Technology) and transformed into dry powder by freeze-drying. The nanosuspension produced was then investigated using optical microscope, photon correlation spectroscopy (PCS), zeta potential measurement, SEM, TEM, AFM, DSC and XRD. To verify the theoretical hypothesis on the benefit of increased surface area, in vitro saturation solubility and dissolution profile were investigated. In addition, the in vitro cell cytotoxicity was examined. Results showed that a narrow size distributed nanosuspension composed of unchanged crystalline state with a mean particle size of 515±18 nm, a polydispersity index of 0.12±0.03 and a zeta potential of -23.1±3.5 mV was obtained. In the in vitro dissolution test an accelerated dissolution velocity and increased saturation solubility could be shown for the MD nanosuspension. The in vitro cytotoxicity experiments provided evidence for an enhanced efficacy of the DM nanosuspension formulation compared to free DM solution. Taken together, these results illustrate the opportunity to formulate DM in nanosuspension form as an anti-prostate cancer delivery system.

In vitro and in vivo evaluation of silybin nanosuspensions for oral and intravenous delivery

In this study, we evaluate the effect of particle sizes on the physicochemical properties of silybin and identify the influence of silybin nanosuspensions on its permeation across the Caco-2 cell monolayer. In vivo pharmacokinetic evaluation of silybin nanosuspensions was also carried out in beagle dogs. TEM, AFM and SEM analyses revealed the effect of homogenization pressure on particle size and morphology, and confirmed the existence of a surfactant-stabilizer film on the surface of nanoparticles. DSC and XRPD experiments manifested that the crystalline state was maintained as particle size was reduced and the enhanced dissolution property was due to the increased surface area. Nanosuspensions had a significant influence on drug transport across the Caco-2 cell monolayer and the enhanced dissolution velocity was responsible for the increased permeability. A pharmacokinetics study in beagle dogs further confirmed the in vitro results and demonstrated that oral administration of silybin nanosuspensions significantly increase its bioavailability compared to the coarse powder. Nanosuspensions of silybin with smaller particle size reveal a higher potential to increase their oral bioavailability; while for intravenous infusion the lower pressure produced silybin nanosuspensions appeared to maintain a more sustained drug release profile.

A facile construction strategy of stable lipid nanoparticles for drug delivery using a hydrogel-thickened microemulsion system

We report a novel facile method for preparing stable nanoparticles with inner spherical solid spheres and an outer hydrogel matrix using a hot O/W hydrogel-thickened microemulsion with spontaneous stability. The nanoparticles with average diameters of about 30.0 nm and 100.0 nm were constructed by cooling the hot hydrogel-thickened microemulsion at different temperatures, respectively. We explained the application of these nanoparticles by actualizing the cutaneous delivery of drug-loaded nanoparticles. The in vitro skin permeation studies showed that the nanoparticles could significantly reduce the penetration of model drugs through skin and resulted in their dermal uptakes in skin. The sol-gel process of TEOS was furthermore used in the template of HTM to regulate the particle size of nanoparticles. The coating of silica on the surface of nanoparticles could regulate the penetration of drug into skin from dermal delivery to transdermal delivery. This strategy provides a facile method to produce nanoparticles with long-term stability and ease of manufacture, which might have a promising application in drug delivery.

A facile nanoaggregation strategy for oral delivery of hydrophobic drugs by utilizing acid-base neutralization reactions

Nanonization strategies have been used to enhance the oral availability of numerous drugs that are poorly soluble in water. Exploring a facile nanonization strategy with highly practical potential is an attractive focus. Here, we report a novel facile nanoaggregation strategy for constructing drug nanoparticles of poorly soluble drugs with pH-dependent solubility by utilizing acid-base neutralization in aqueous solution, thus facilitating the exploration of nanonization in oral delivery for general applicability. We demonstrate that hydrophobic itraconazole dissolved in acid solution formed a growing core and aggregated into nanoparticles in the presence of stabilizers. The nanoparticles, with an average diameter of 279.3 nm and polydispersity index of 0.116, showed a higher dissolution rate when compared with the marketed formulation; the average dissolution was about 91.3%. The in vivo pharmacokinetic studies revealed that the nanoparticles had a rapid absorption and enhanced oral availability. The diet state also showed insignificant impact on the absorption of itraconazole from nanoparticles. This nanoaggregation strategy is a promising nanonization method with a facile process and avoidance of toxic organic solvents for oral delivery of poorly soluble drugs with pH-dependent solubility and reveals a highly practical potential in the pharmaceutical and chemical industries.