Evaluation of the Formulation Parameter-Dependent Redispersibility of API Nanoparticles from Fluid Bed Granules

The production of nanosuspensions of poorly soluble active pharmaceutical ingredients (API) is a popular technique to counteract challenges regarding bioavailability of such active substances. A subsequent drying of the nanosuspensions is advantageous to improve the long-term stability and the further processing into solid oral dosage forms. However, associated drying operations are critical, especially with regard to nanoparticle growth, loss in redispersibility and associated compromised bioavailability. This work extends a previous study regarding the applicability of an API (itraconazole) nanosuspension as a granulation liquid in a fluidized bed process with focus on the influence of applied formulation parameters on the structure of obtained nanoparticle-loaded granules and their nanoparticle redispersibility. Generally, a higher dissolution rate of the carrier material (glass beads, lactose, mannitol or sucrose) and a higher content of a matrix former/hydrophilic polymer (PVP/VA or HPMC) in the granulation liquid resulted in the formation of coarser and more porous granules with improved nanoparticle redispersibility. HPMC was found to have advantages as a polymer compared with PVP/VA. In general, a better redispersibility of the nanoparticles from the granules could be associated with better dispersion of the API nanoparticles at the surface of the granules as deduced from the thickness of nanoparticle-loaded layers around the granules. The layer thickness on granules was assessed by means of confocal Raman microscopy. Finally, the dispersion of the nanoparticles in the granule layers was exemplarily described by calculation of theoretical mean nanoparticle distances in the granule layers and was correlated with data obtained from redispersibility studies.

Optimization of the Conditions of Solid Lipid Nanoparticles (SLN) Synthesis

Solid lipid nanoparticles (SLNs) have been synthesized as potential drug delivery systems. They are classified as solid lipid nanocarriers that can successfully carry both hydrophilic and hydrophobic drugs. SLNs are based on a biocompatible lipid matrix that is enzymatically degraded into natural components found in the human body. Solid lipid nanoparticles are suitable for the incorporation of hydrophobic active ingredients such as curcumin. The study included the optimization of lipid nanoparticle composition, incorporation of the active compound (curcumin), a stability evaluation of the obtained nanocarriers and characterization of their lipid matrix. Through process optimization, a dispersion of solid lipid nanoparticles (solid lipid:surfactant—2:1.25 weight ratio) predisposed to the incorporation of curcumin was developed. The encapsulation efficiency of the active ingredient was determined to be 99.80%. In stability studies, it was found that the most suitable conditions for conducting high-pressure homogenization are 300 bar pressure, three cycles and a closed-loop system. This yields the required values of the physicochemical parameters (a particle size within a 200−450 nm range; a polydispersity index of <30%; and a zeta potential of about |±30 mV|). In this work, closed-loop high-pressure homogenization was used for the first time and compared to the currently preferred open-loop method.

Formulation of drug-loaded oligodepsipeptide particles with submicron size

The size of particulate carriers is key to their transport and distribution in biological systems, and needs to be tailored in the higher submicron range to enable follicular uptake for dermal treatment. Oligodepsipeptides are promising nanoparticulate carrier systems as they can be designed to exhibit enhanced interaction with drug molecules. Here, a fabrication scheme for drug-loaded submicron particles from oligo[3-(S)-sec-butylmorpholine-2,5-dione]diol (OBMD) is presented based on an emulsion solvent evaporation method with cosolvent, surfactant, and polymer concentration as variable process parameters. The particle size (300-950 nm) increased with lower surfactant concentration and higher oligomer concentration. The addition of acetone increased the particle size at low surfactant concentration. Particle size remained stable upon the encapsulation of models compounds dexamethasone (DXM) and Nile red (NR), having different physicochemical properties. DXM was released faster compared to NR due to its higher water solubility. Overall, the results indicated that both drug-loading and size control of OBMD submicron particles can be achieved. When applied on porcine ear skin samples, the NR-loaded particles have been shown to allow NR penetration into the hair follicle and the depth reached with the 300 nm particles was comparable to the one reached with the cream formulation. A potential benefit of the particles compared to a cream is their sustained release profile.

Nanoliposomal thyme (Thymus vulgaris) essential oil: Effects of formulation parameters

Essential oils with antimicrobial or antioxidant activities have received extensive attention among customers, manufacturers, and food scientists, especially with rising worries about the safety of synthetic food preservatives. However, like other functional lipid compounds their incorporation into aqueous systems is challenging, due to their less water solubility. Furthermore, their susceptibility to light, moisture, heat, and oxygen origins their less chemical and structural stabilities. Consequently, the present research was aimed to encapsulate the thyme essential oil into nanoliposomes, using a thin layer hydration-sonication technique, which can be a proficient solution for revealed problems. The effects of phospholipid and stabilizing agents' concentrations, namely, lecithin, cholesterol, and glycerol, as main formulation parameters were investigated on characteristics of gained nanoliposomes, using a response surface method. Various empirical models were also developed to predict product characteristics by changing the formulation parameters. According to the numerical multiple optimizations, the best thyme oil nanoliposomes can be gained using equal concentrations of all three components as 1% with a mean particle size of 189.6 nm, PDI of 0.3487, the net zeta-potential of 42.48 mV, and DPPH radical scavenging of 12.72%. The prepared nanoliposomes had acceptable physical but limited chemical stabilities. The antibacterial action of manufactured essential oil nanoliposomes against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus has made them efficient candidates as natural food preservatives.

Comparison of the In Vitro and Ex Vivo Permeation of Existing Topical Formulations Used in the Treatment of Facial Angiofibroma and Characterization of the Variations Observed

Rapamycin has been used topically to treat facial angiofibromas associated with tuberous sclerosis for more than a decade. In the absence of a commercial form, a large number of formulations have been clinically tested. However, given the great heterogeneity of these studies, particularly with regard to the response criteria, it was difficult to know the impact and thus to compare the relevance of the formulations used. The objective of this work was therefore to evaluate the link between the diffusion of rapamycin and the physico-chemical characteristics of these different formulations on Strat-M^® membranes as well as on human skin using Franz cells. Our results underline the importance of the type of vehicle used (hydrogel > cream > lipophilic ointment), the soluble state of rapamycin and its concentration close to saturation to ensure maximum thermodynamic activity. Thus, this is the first time that a comparative study of the different rapamycin formulations identified in the literature for the management of facial angiofibromas has been carried out using a pharmaceutical and biopharmaceutical approach. It highlights the important parameters to be considered in the development and optimization of topical rapamycin formulations with regard to cutaneous absorption for clinical efficacy.

Influence of Formulation Parameters on Redispersibility of Naproxen Nanoparticles from Granules Produced in a Fluidized Bed Process

The particle size reduction of active pharmaceutical ingredients is an efficient method to overcome challenges associated with a poor aqueous solubility. With respect to stability and patient's convenience, the corresponding nanosuspensions are often further processed to solid dosage forms. In this regard, the influence of several formulation parameters (i.e., type of carrier material, type and amount of additional polymeric drying excipient in the nanosuspension) on the redispersibility of naproxen nanoparticle-loaded granules produced in a fluidized bed process was investigated. The dissolution rate of the carrier material (i.e., sucrose, mannitol, or lactose) was identified as a relevant material property, with higher dissolution rates (sucrose > mannitol > lactose) resulting in better redispersibility of the products. Additionally, the redispersibility of the product granules was observed to improve with increasing amounts of polymeric drying excipient in the nanosuspension. The redispersibility was observed to qualitatively correlate with the degree of nanoparticle embedding on the surface of the corresponding granules. This embedding was assumed to be either caused by a partial dissolution and subsequent resolidification of the carrier surface dependent on the dissolution rate of the carrier material or by resolidification of the dissolved polymeric drying excipient upon drying. As the correlation between the redispersibility and the morphology of the corresponding granules was observed for all investigated formulation parameters, it may be assumed that the redispersibility of the nanoparticles is determined by their distance in the dried state.

Evaluation of Formulation Parameters on Permeation of Ibuprofen from Topical Formulations Using Strat-M® Membrane

Topical drug delivery is an attractive alternative to conventional methods because of advantages such as non-invasive delivery, by-pass of first pass metabolism, and improved patient compliance. However, several factors such as skin, physicochemical properties of the drug, and vehicle characteristics influence the permeation. Within a formulation, critical factors such as concentration of drug, physical state of drug in the formulation, and organoleptic properties affect the flux across the skin. The aim of the study was to develop and investigate topical semisolid preparations (creams and gels) with ibuprofen as the model drug and investigate the effect of various formulation parameters on the in-vitro performance across the Strat-M® membrane using flow-through cells. In addition, the physical stability of the developed formulations was investigated by studying viscosity, pH, and appearance. All the formulations developed in the study had appealing appearance with smooth texture and no signs of separation. Viscosity and pH of the formulations were acceptable. Cumulative amount of drug permeated at the end of 24 h was highest for clear gel (3% w/w ibuprofen; F6: 739.6 ± 36.1 µg/cm2) followed by cream with high concentration of ibuprofen in suspended form (5% w/w; F3: 320.8 ± 17.53 µg/cm2), emulgel (3% w/w ibuprofen; F5: 178.5 ± 34.5 µg/cm2), and cream with solubilized ibuprofen (3% w/w; F2A: 163.2 ± 9.36 µg/cm2). Results from this study showed that permeation of ibuprofen was significantly influenced by formulation parameters such as concentration of ibuprofen (3% vs. 5% w/w), physical state of ibuprofen (solubilized vs. suspended), formulation type (cream vs. gel), mucoadhesive agents, and viscosity (high vs. low). Thus, findings from this study indicate that pharmaceutical formulation scientists should explore these critical factors during the early development of any new topical drug product in order to meet pre-determined quality target product profile.

Nasal formulations for drug administration and characterization of nasal preparations in drug delivery

This special report gives an insight in the rationale of utilizing the nasal cavity for drug administration and the formulation as well as characterization of nasal preparations. As the nose is an easy-to-access, noninvasive and versatile location for absorption, this route of delivery will play an increasingly important role in future drug product development both for new and repurposed drugs. The nose can be utilized for local and systemic delivery including drug delivery to the central nervous system and the immune system. Typical formulation strategies and future developments are reviewed, which nowadays mostly comprise liquid formulations. Although they are straight forward to develop, a number of aspects from choice of solvent, osmolarity, pH, viscosity and more need to be considered, which determine formulation characteristics, not at least nasal deposition. Nasal powders offer higher stability and, along with more sophisticated nasal devices, may play a major role in the future.