A Package of Established Analytical Tools to Investigate the Solid-State Alteration of Lipid-Based Excipients.

Lipid-based excipients (LBEs) are low-toxic, biocompatible, and natural-based, and their application supports the sustainability of pharmaceutical manufacturing. However, the major challenge is their unstable solid-state, affecting the stability of the pharmaceutical product. Critical physical properties of lipids for their processing-such as melt temperature and viscosity, rheology, etc.

Insights into the Impact of Nanostructural Properties on Powder Tribocharging: The Case of Milled Salbutamol Sulfate.

The impact of the crystallinity of organic solid materials on their tribocharging propensity is well reported. However, no unequivocal explanation about the potential underlying mechanism(s) could be found so far in the literature. This study reports the effect that different degrees of crystalline disorder has on the tribocharging propensity of a small molecular organic material, salbutamol sulfate (SS).

Phase Behavior of Drug-Lipid-Surfactant Ternary Systems toward Understanding the Annealing-Induced Change.

The present study systematically investigates the effect of annealing conditions and the Kolliphor P 407 content on the physicochemical and structural properties of Compritol (glyceryl behenate) and ternary systems prepared via melt cooling (Kolliphor P 407, Compritol, and a hydrophilic API) representing solid-lipid formulations. The physical properties of Compritol and the ternary systems with varying ratios of Compritol and Kolliphor P 407 were characterized using differential scanning calorimetry (DSC), small- and wide-angle X-ray scattering (SWAXS) and infrared (IR) spectroscopy, and hot-stage microscopy (HSM), before and after annealing. The change in the chemical profiles of different Compritol components as a function of annealing was evaluated using H NMR spectroscopy.

Impact of polysorbate 65 on tripalmitin crystal growth and release stability of hot melt coated multiparticulate systems.

Hydrochlorothiazide (HCT) multiparticulate systems (MPS) were hot melt coated with the binary mixture of tripalmitin (PPP) and polysorbate 65 (PS 65) to gain an immediate release profile. Once, HCT MPS were produced with a constant ratio of PPP/PS 65 (90:10) at three different coating amounts (15, 25, and 60%) and once the PPP/PS 65 ratio was varied on 98:2 and 80:20, by keeping the coating amount at 60%. PS 65 induced the polymorphic transformation of PPP from the α-form to its most stable β-form right after the hot melt coating (HMC).

Impact of simulated lung fluid components on the solubility of inhaled drugs and predicted in vivo performance.

Orally inhaled products (OIPs) are gaining increased attention, as pulmonary delivery is a preferred route for the treatment of various diseases. Yet, the field of inhalation biopharmaceutics is still in development phase. For a successful correlation between various in vitro data obtained during formulation characterization and in vivo performance, it is necessary to understand the impact of parameters such as solubility and dissolution of drugs.

Interplay of Aging and Lot-to-Lot Variability on the Physical and Chemical Properties of Excipients: A Case Study of Mono- and Diglycerides.

The present study investigates the chemical composition governing the physical properties of mono- and diglycerides (MDGs) at the microstructural level, as a function of aging and lot-to-lot variability. The physical structure of the MDG plays a vital role in ameliorating the emulsion stability and is widely explored in diverse research horizons related to the pharmaceutical, cosmetic, and food industries. In an effort to understand the mechanism of emulsion stabilization, physical properties were extensively evaluated in selective commercial lots to determine if there is a correlation between the chemical composition of MDG and physical properties.

Polyethylene oxide matrix tablet swelling evolution: The impact of molecular mass and tablet composition.

This article describes the designing of matrix tablets composed of polyethylene oxides (PEOs) with relative molecular masses of 1 × 106, 2 × 106, and 4 × 106. Percolation thresholds were determined for all of the selected PEO formulations (18, 16, and 12 %, m/m), taking into consideration excipients and tablet surface area which significantly increased the percolation threshold. Moreover, the robustness of the gel layer in PEO matrix tablets was evaluated by magnetic resonance imaging under various mechanical stresses (no flow, 12 mL min-1, and 64 mL-1 of medium flow).

Polyelectrolyte-surfactant-complex nanoparticles as a delivery platform for poorly soluble drugs: A case study of ibuprofen loaded cetylpyridinium-alginate system.

Previously, we reported on the surfactant cetylpyridinium chloride (CPC) as a crosslinker of alginate for the formation of stable polyelectrolyte-surfactant-complex nanoparticles. Here, we evaluate this system for increased solubility of a poorly soluble drug. The aim was to use CPC for solubilisation of ibuprofen and to use the micellar associates formed for alginate complexation and nanoparticle formation.

Evolution of the microstructure and the drug release upon annealing the drug loaded lipid-surfactant microspheres.

The present study investigates the drug release-governing microstructural properties of melt spray congealed microspheres encapsulating the drug crystals in the matrix of glyceryl behenate and poloxamer (pore former). The solid-state, morphology, and micromeritics of the microspheres were characterized, before and after annealing, using calorimetry, X-ray scattering, porosimetry, scanning electron microscopy, and, NMR diffusometry. The in vitro drug release from and water uptake by the microspheres were obtained.

Solid-State Reactivity of Mechano-Activated Simvastatin: Atypical Relation to Powder Crystallinity.

The present study investigated the impact of solid-state disorders generated during milling on the chemical reactivity of simvastatin. An amorphous and a partially crystalline simvastatin powders were generated via cryomilling simvastatin crystals for either 90 or 10 min, respectively. The thoroughly characterized milled powders were stored at 40°C/75% RH, in open and closed containers.

Correlation between the solid state of lipid coating and release profile of API from hot melt coated microcapsules.

Solvent-free hot melt coating (HMC) provides a safer and more economic process compared to the conventional solvent coating techniques. However, drug release instability and the lack of fundamental understanding on it are limiting factors for application of HMC for industrial productions. In this work, we investigated glyceryl dibehenate, glyceryl monostearate and behenoyl polyoxyl-8 glyceride as HMC materials.

Density fluctuations in amorphous pharmaceutical solids. Can SAXS help to predict stability?

The analytical potential of X-ray small-angle scattering (SAXS) combined with simultaneous wide-angle diffraction (WAXS) has been explored on the example of three active pharmaceutical ingredients, (desvenlofaxine, simvastatin, and sulfamerazine, resp.) with the aim of identifying quantitative parameters obtained from SAXS that allow to describe the nano-structural characteristics of different amorphous forms and to monitor the processes of amorphisation and ageing. Cryo-milling, co-milling with polymer, melting and melt-quenching have been used for amorphisation of initially crystalline powders.

Effect of Technically Relevant X-Ray Doses on the Structure and Function of Alcohol Dehydrogenase and Hen Egg-White Lysozyme.

Purpose: The effect of different irradiation doses on the structure and activity of lyophilized powders of Hen Egg-White Lysozyme (HEWL) and alcohol dehydrogenase (ADH) was investigated using these substances as models for robust and sensitive proteins, respectively. Three doses were selected to cover the ranges of radio-sterilization (25kGy), treatment of blood products (25Gy) and annual background radiation dose (approximately 2mGy). The results offer an initial screening of different irradiation doses and support the development of X-ray imaging methods as non-destructive process analytical technology (PAT) tools for detecting the visible particulate matters in such products.

Self-emulsification of Lipidic Drug Delivery System in Pure Water and in Concentrated Glycerol Solution.

Self-emulsifying drug delivery systems (SEDDS), often intended for oral delivery, are normally explored in biorelevant aqueous media. The high complexity of these multi-component systems leaves the understanding of self-emulsification poor, hindering formulation rationalization. In this work, we aimed to fill this gap by studying the effects of glycerol on the self-emulsification of a ternary component formulation made of 20% w/w Tween 80, 15% w/w Span 80, and 65% w/w Captex 300 Low C6.

Microphase separation in solid lipid dosage forms as the cause of drug release instability.

Although lipid excipients are of increasing interest for development of taste-masked and modified release formulations, the drug release instability and the lack of mechanistic understanding in that regard still prevent their larger-scale application. In this work, we investigated the physical stability of a binary (tripalmitin/polysorbate 65) lipid coating formulation with a known stable polymorphism. The coating composition was characterized using DSC to construct the phase diagram of binary system and polarized light microscopy to display the microstructure organization.

The influence of residual water on the solid-state properties of freeze-dried fibrinogen.

The purpose of this work was to investigate the influence of residual water in freeze-dried protein powders on the dissolution behavior of the solid-state proteins. To that end, six freeze-dried fibrinogen powder lots were stored at four levels of relative humidity and analyzed with regard to the particle size and shape, the specific surface area, the solid state of protein and the inner surface. Furthermore, the dissolution behavior of the powders was investigated.

Specific surface, crystallinity, and dissolution of lyophilized fibrinogen. A study by combined small- and wide-angle X-ray scattering (SWAXS).

The nano-structural properties of six different batches of lyophilized fibrinogen at various contents of residual humidity (6-20%) were studied by small- and wide-angle X-ray scattering (SWAXS) and related to the dissolution properties. As structural parameters, the specific surface and relative degree of crystallinity, from SAXS and WAXS, respectively, were used, and correlated to the dissolution rates. BET surface area and electron microscopy were used as ancillary methods.

Small- and wide-angle X-ray scattering (SWAXS) for quantification of aspirin content in a binary powder mixture.

This article presents a novel application of small and wide angle X-ray scattering (SWAXS) in the assessment of aspirin and lactose content in a binary pharmaceutical powder formulation. It is shown that the content correlates with the intensity of the SAXS signal and the intensity of polymorph fingerprints in the WAXS spectra that are collected from the same samples. Because the polymorph WAXS fingerprints and the SAXS signal are two independent characteristics of the same sample, simultaneous SWAXS analysis provides the basis for a dual independent assessment of the same contents.

Stable and unstable lipid domains in ceramide-containing membranes.

We applied x-ray diffraction, calorimetry, and infrared spectroscopy to lipid mixtures of palmitoyl-oleoyl phosphatidylcholine, sphingomyelin, and ceramide. This combination of experimental techniques allowed us to probe the stability and structural properties of coexisting lipid domains without resorting to any molecular probes. In particular, we found unstable microscopic domains (compositional/phase fluctuations) in the absence of ceramide, and macroscopically separated fluid and gel phases upon addition of ceramide.

Mesostructured silica aerosol particles: comparison of gas-phase and powder deposit X-ray diffraction data.

We report on the characterization of mesostructured aerosol silica particles in the gas phase using in situ synchrotron small-angle X-ray scattering (SAXS) in order to unveil the influence of the basic production parameters. The investigated system was based on tetraethylorthosilicate (TEOS) as the inorganic precursor and on cetyltrimethyl-ammonium bromide (CTAB) as the surfactant. The heating temperature, surfactant to silicate ratio, and particle flow rate were thoroughly investigated, and for this purpose, an in-house-built aerosol reactor equipped with a special X-ray observation chamber was used.

Interactions of the AT1 antagonist valsartan with dipalmitoyl-phosphatidylcholine bilayers.

Valsartan is a marketed drug with high affinity to the type 1 angiotensin (AT1) receptor. It has been reported that AT1 antagonists may reach the receptor site by diffusion through the plasma membrane. For this reason we have applied a combination of differential scanning calorimetry (DSC), Raman spectroscopy and small and wide angle X-ray scattering (SAXS and WAXS) to investigate the interactions of valsartan with the model membrane of dipalmitoyl-phosphatidylcholine (DPPC).

Implication of sphingomyelin/ceramide molar ratio on the biological activity of sphingomyelinase.

Sphingolipid signaling plays an important, yet not fully understood, role in diverse aspects of cellular life. Sphingomyelinase is a major enzyme in these signaling pathways, catalyzing hydrolysis of sphingomyelin to ceramide and phosphocholine. To address the related membrane dynamical structural changes and their feedback to enzyme activity, we have studied the effect of enzymatically generated ceramide in situ on the properties of a well-defined lipid model system.

Effect of ceramide on nonraft proteins.

The currently accepted model of biological membranes involves a heterogeneous, highly dynamic organization, where certain lipids and proteins associate to form cooperative platforms ("rafts") for cellular signaling or transport processes. Ceramides, a lipid species occurring under conditions of cellular stress and apoptosis, are considered to stabilize these platforms, thus modulating cellular function. The present study focuses on a previously unrecognized effect of ceramide generation.

Biophysical characterization of the fusogenic region of HCV envelope glycoprotein E1.

We have studied the binding and interaction of the peptide E1(FP) with various model membranes. E1(FP) is derived from the amino acid segment 274-291 of the hepatitis C virus envelope glycoprotein E1, which was previously proposed to host the peptide responsible for fusion to target membranes. In the present study we addressed the changes which take place upon E1(FP) binding in both the peptide and the phospholipid bilayer, respectively, through a series of complementary experiments.

Effect of selenium on characteristics of rape chloroplasts modified by cadmium.

Selenium appears to be an important protective agent that decreases cadmium-induced toxic effects in animals and plants. The aim of these studies was to investigate the changes of properties of chloroplast membranes obtained from Cd-treated rape seedlings caused by Se additions. Chloroplasts were isolated from leaves of 3-week-old rape plants cultured on Murashige-Skoog media supplied with 2 microM Na(2)SeO(4) and/or 400 microM CdCl(2) under in vitro conditions.