Liquid Formulations for Stabilizing IgMs During Physical Stress and Long-Term Storage

Purpose

To develop a liquid formulation for IgMs to survive physical stress and storage.

Methods

Stabilizing formulations for 8 monoclonal immunoglobulin (IgMs) were found using differential scanning calorimetry (DSC). In these formulations, the IgMs were subjected to stress and storage and analyzed by size exclusion chromatography and fluorescence activated cell sorting. Structure was analyzed using small-angle X-ray scattering (SAXS).

Results

The highest conformational stability was found near the isoelectric point and further enhanced by addition of sorbitol, sucrose and glycine. For 2 IgMs, the pH optimum for conformational and storage stability did not correspond. Lowering the pH led to the desired storage stability. Optimized formulations prevented aggregation and fragmentation from shear stress, freeze-thaw cycles, accelerated storage and real time storage at 4°C and ?20°C for 12 months. Optimized formulations also preserved immunoreactivity for 12 months. SAXS indicated that IgM in stabilizing conditions was closer to the structural IgM model (2RCJ) and less susceptible for aggregation.

Conclusions

A long-term stabilizing formulation for 8 IgMs was found comprising 20% sorbitol and 1 M glycine at pH 5.0–5.5 which may have broad utility for other IgMs. Formulation development using DSC and accelerated storage was evaluated in this study and may be used for other proteins.     

The Degradation of Polysorbates 20 and 80 and its Potential Impact on the Stability of Biotherapeutics

Purpose

To study the potential impact of the degradation of Polysorbates (PS) 20 and 80 on the stability of therapeutic proteins in parenteral formulations.

Method

First, degradation products of PS20 and 80 were identified. Subsequently, the effect of degraded polysorbate on physical characteristics and long-term stability of protein formulations was assessed. Further, the impact of polysorbate degradation on protein stability was evaluated via shaking stress studies on formulations spiked with artificially degraded polysorbate or degradants like fatty acids. Additionally, aged formulations with reduced polysorbate content were shaken.

Results

The degradation of polysorbate leads to a buildup of various molecules, some of which are poorly soluble, including fatty acids and polyoxyethylene (POE) esters of fatty acids. Spiking studies showed that the insoluble degradants could potentially impact protein stability and that the presence of sufficient intact polysorbate was crucial to prevent this. End-of-shelf-life shaking of protein formulations showed that the stability of various monoclonal antibodies was, however, not affected.

Conclusions

Although some degradants can potentially influence the stability of the protein (as discerned from spiking studies), degradation of polysorbates did not impact the stability of the different proteins tested in pharmaceutically relevant temperature and storage conditions.     

Rapid Intradermal Delivery of Liquid Formulations Using a Hollow Microstructured Array

Purpose

The purpose of this work is to demonstrate rapid intradermal delivery of up to 1.5 mL of formulation using a hollow microneedle delivery device designed for self-application.

Methods

3M??s hollow Microstructured Transdermal System (hMTS) was applied to domestic swine to demonstrate delivery of a variety of formulations including small molecule salts and proteins. Blood samples were collected after delivery and analyzed via HPLC or ELISA to provide a PK profile for the delivered drug. Site evaluations were conducted post delivery to determine skin tolerability.

Results

Up to 1.5 mL of formulation was infused into swine at a max rate of approximately 0.25 mL/min. A red blotch, the size of the hMTS array, was observed immediately after patch removal, but had faded so as to be almost indistinguishable 10 min post-patch removal. One-mL deliveries of commercial formulations of naloxone hydrochloride and human growth hormone and a formulation of equine anti-tetanus toxin were completed in swine. With few notable differences, the resulting PK profiles were similar to those achieved following subcutaneous injection of these formulations.

Conclusions

3M??s hMTS can provide rapid, intradermal delivery of 300?C1,500 µL of liquid formulations of small molecules salts and proteins, compounds not typically compatible with passive transdermal delivery.     

Effect of pH and Excipients on Structure, Dynamics, and Long-Term Stability of a Model IgG1 Monoclonal Antibody upon Freeze-Drying

Purpose

To investigate the mechanism of IgG1 mAb stabilization after freeze-drying and the interdependence of protein structural preservation in the solid state, glassy state dynamics and long-term storage stability under different formulation conditions.

Methods

IgG1 mAb was formulated with mannitol at pH 3.0, 5.0, and 7.0 in the presence and absence of sucrose and stability was monitored over 1 year at different temperatures. Physical and covalent degradation of lyophilized formulation was monitored using SEC, CEX, and light obscuration technique. Secondary and tertiary structure of the protein in the solid state was characterized using FTIR and fluorescence spectroscopy respectively. Raman spectroscopy was also used to monitor changes in secondary and tertiary structure, while SS-NMR ¹H relaxation was used to monitor glassy state dynamics.

Results

IgG1 mAb underwent significant secondary structural perturbations at pH 3.0 and conditions without sucrose, while pH 5.0 condition with sucrose showed the least structural change over time. The structural changes correlated with long-term stability with respect to protein aggregate formation and SbVP counts. SS-NMR data showed reduced relaxation time at conditions that were more stable.

Conclusions

Native state protein structural preservation and optimal solid-state dynamics correlate with improved long-term stability of the mAb in the different lyophilized formulations.     

Microstructural Elucidation of Self-Emulsifying System: Effect of Chemical Structure

Purpose

Self-emulsifying systems (SES) emulsify spontaneously to produce fine oil-in-water emulsion when introduced into aqueous phase. The self-emulsification process plays an important role during formation of emulsion. The objective of current work was to understand and explore the inner structuration of SES through controlled hydration and further to study the influence of additive on the same which ultimately governs performance of final formulation in terms of droplet size.

Methods

Droplet size of final formulations containing structural analogues of ibuprofen was determined. Microstructural properties of intermediate hydrated regimes of SES were investigated using techniques such as small angle X-ray scattering, differential scanning calorimetry and rheology.

Results

The current work established inverse relationship between droplet size of the formulations containing structural analogues of ibuprofen and their Log P values. Microstructural analysis of intermediate hydrated regimes of the prepared samples showed formation of local lamellar structure. Structural analogues of ibuprofen significantly altered microstructure of lamellae which was well correlated with the droplet size of final formulations. In vitro drug release study showed increase in dissolution rate of lipophillic drugs when formulated as SES.

Conclusion

The current work emphasizes the fact that tailor-made formulations can be prepared by controlling the properties of intermediate regimes.

Beyond Glass Transitions: Studying the Highly Viscous and Elastic Behavior of Frozen Protein Formulations Using Low Temperature Rheology and Its Potential Implications on Protein Stability

Purpose

A novel application of oscillatory shear rheology was used to directly monitor global phase behavior of protein formulations in the frozen state and study its correlation with physical instability of frozen protein formulations.

Methods

Oscillatory rheology was used to measure changes in rheological parameters and to identify mechanical softening temperature (Ts*) and related properties of an IgG2 mAb formulation. Rheological measurements were compared to DSC/MDSC. Physical stability of IgG2 formulations was monitored by SE-HPLC.

Results

Rheological parameters and Ts* of an IgG2 formulation were sensitive to physical/morphological phase changes during freezing and thawing. Ts* of the frozen formulation was a function of concentration of protein and excipient. Complex modulus, G*, and phase angle, δ, for IgG2 at 70 mg/mL in a sucrose-containing formulation showed the system was not completely frozen at ?10°C, which correlated to stability data consistent with ice-induced protein aggregation.

Conclusions

We report the first application of oscillatory shear rheology to study phase behavior of IgG2 in a sucrose-containing formulation and its correspondence with physical stability not explained by glass transition (Tg’). We provide a mechanism and data suggesting that protein instability occurs at the ice/water interface.     

Physical Stability of Freeze-Dried Isomalt Diastereomer Mixtures

Purpose

Isomalt is a sugar alcohol used as an excipient in commercially available solid oral dosage forms. The potential of isomalt as a novel freeze-drying excipient was studied in order to increase knowledge of the behavior of isomalt when it is freeze-dried.

Methods

Isomalt was freeze-dried in four different diastereomer compositions and its physical stability was investigated with differential scanning calorimetry, Fourier-transform infrared and Raman spectroscopy, X-ray powder diffraction, Karl-Fischer titration and thermogravimetric analysis in order to verify the solid state form of isomalt after freeze-drying and observe any changes occurring during storage in three different relative humidity conditions.

Results

Isomalt was successfully transformed into the amorphous form with freeze-drying and three diastereomer combinations remained stable as amorphous during storage; one of the diastereomer compositions showed signs of physical instability when stored in the highest relative humidity condition. The four different crystalline diastereomer mixtures showed specific identifiable solid state properties.

Conclusions

Isomalt was shown to be a suitable excipient for freeze-drying. Preferably a mixture of the diastereomers should be used, as the mixture containing only one of the isomers showed physical instability. A mixture containing a 1:1 ratio of the two diastereomers showed the best physical stability in the amorphous form.

     

Electrolyte-Stimulated Biphasic Dissolution Profile and Stability Enhancement for Tablets Containing Drug-Polyelectrolyte Complexes

Purpose

Recently introduced drug-polyelectrolyte complexes prepared by hot-melt extrusion should be processed to solid dosage forms with tailor-made release properties. Their potential of stability enhancement should be investigated.

Methods

Milled hot-melt extruded naproxen-EUDRAGIT? E PO polyelectrolyte complexes were subsequently processed to double-layer tablets with varying complex loadings on a rotary-die press. Physicochemical interactions were studied under ICH guideline conditions and using the Gordon-Taylor equation. Sorption and desorption were determined to investigate the influence of moisture and temperature on the complex and related to stability tests under accelerated conditions.

Results

Naproxen release from the drug-polyelectrolyte complex is triggered by electrolyte concentration. Depending on the complex loading, phosphate buffer pH 6.8 stimulated a biphasic dissolution profile of the produced double-layer tablets: immediate release from the first layer with 65% loading and prolonged release from the second layer within 24?h (98.5% loading). XRPD patterns proved pseudopolymorphism for tablets containing the pure drug under common storage conditions whereas the drug-complex was stable in the amorphous state.

Conclusions

Drug-polyelectrolyte complexes enable tailor-made dissolution profiles of solid dosage forms by electrolyte stimulation and increase stability under common storage conditions.     

Formulation and Development of CoQ10-Loaded s-SNEDDS for Enhancement of Oral Bioavailability

Purpose

Coenzyme (CoQ10) is a poorly soluble drug strategically selected to enrich oral bioavailability by incorporating in solid self-nanoemulsifying drug delivery system (s-SNEDDS) comprised of oil, surfactant, and cosurfactant. The conventional self-emulsifying drug delivery system (SEDDS) and liquid SNEDDS (l-SNEDDS) usually have the problem of drug instability and precipitation.

Methods

The selected oils, surfactant, and cosurfactant with maximum drug solubility were Lauroglycol FCC, Labrasol, and Transcutol P. The ternary phase diagrams were constructed, and selected formulations from ternary phase diagrams were subjected to thermodynamic stability and self-dispersibility test and characterized for emulsion droplet size and droplet size distribution. The optimized formulation was comprised of Lauroglycol FCC 20 % (w/w), Labrasol 10 % (w/w), and Transcutol P 20 % (w/w) as oil, surfactant, and cosurfactant.

Results

The transmission electron microscopy (TEM) study of optimized l-SNEDDS reported mean globule size of 34 nm was transformed into s-SNEDDS by spray-drying technique using solid carrier. The s-SNEDDS was characterized for differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and X-ray diffraction (X RD). The in vitro release profile of s-SNEDDS showed drug release (97.5?±?4.5 %), marketed formulation (57.96?±?0.54 %), and CoQ10 powder (0.36?±?0.06 %) in 1 hour. The pharmacokinetic study of optimized s-SNEDDS in male Wistar rats revealed the improved maximum concentration (C _max) (3.4-fold vs CoQ10 powder; 1.4-fold vs marketed formulation) and area under the curve (AUC) (5-fold vs CoQ10 powder; 2-fold vs marketed formulation). With this result, s-SNEDDS could be of potential to enhance the oral bioavailability of CoQ10.

Conclusion

Thus, s-SNEDDS in addition to enhancing the dissolution and oral bioavailability often results in low production cost, easy processing, and better patient compliance.     

Towards a More Desirable Dry Powder Inhaler Formulation: Large Spray-Dried Mannitol Microspheres Outperform Small Microspheres

Purpose

To investigate, for the first time, the performance of a dry powder inhaler (DPI, Aerolizer^®) in the case of a model drug (i.e. albuterol sulphate) formulated with spray dried mannitol carrier particles with homogeneous shape and solid–state form but different sizes.

Methods

Spray dried mannitol (SDM) particles were characterized in terms of size, surface area, morphology, water content, solid–state, density and electrostatic charge by a novel approach. DPI formulations composed of SDM and albuterol sulphate (AS) were prepared and evaluated in terms of drug content homogeneity and in vitro aerosolization performance.

Results

All SDM particles generated similar fine particle fractions of AS. Formulations consisting of larger SDM particles demonstrated better drug content homogeneity, reduced amounts of drug loss and reduced oropharyngeal deposition. Comparing different SDM products demonstrated that SDM powders with relatively poorer flowability, wider size distributions and higher charge density generated DPI formulations with poorer drug content homogeneity and deposited higher amount of drug on the inhaler, mouthpiece adaptor and throat. DPI formulation total desirability increased linearly with the mean diameter of SDM.

Conclusion

Particle shape and solid–state form of mannitol could dominate over carrier size, bulk density, flowability and charge in terms of determining the aerosolization behaviour of AS formulated with mannitol carrier, at least within the experimental protocols applied in the present study.     

Fluorescence Single Particle Tracking for the Characterization of Submicron Protein Aggregates in Biological Fluids and Complex Formulations

Purpose

To evaluate the potential of fluorescence single particle tracking (fSPT) for the characterization of submicron protein aggregates in human serum, plasma and formulations containing human serum albumin (HSA).

Methods

A monoclonal IgG was covalently labeled with a fluorescent dye and cross-linked with glutaraldehyde. IgG aggregates and fluorescent beads of 0.1 ??m (control) were diluted in buffer, serum and plasma, and their size distributions were analyzed by fSPT and nanoparticle tracking analysis (NTA). In a separate experiment, IgG and HSA, fluorescently labeled with different dyes, were mixed and subjected to heat stress. The stressed sample was analyzed by fSPT using a dual color mode and by NTA.

Results

The accuracy and precision of fSPT proved to be comparable to NTA. fSPT was able to successfully measure all the samples in buffer, serum and plasma. The average size of the cross-linked protein aggregates showed a slight increase in biological fluids. Moreover, fSPT analysis showed that a significant proportion of the aggregates formed by subjecting an IgG/HSA mixture to heat stress were composed of both proteins.

Conclusion

fSPT is a powerful technique for the characterization of submicron protein aggregates in biological fluids and complex formulations.     

Evaluation of the Crystallization Tendency of Commercially Available Amorphous Tacrolimus Formulations Exposed to Different Stress Conditions

Purpose

Tacrolimus, an immunosuppressant, is a poorly water soluble compound whereby the commercially available capsule formulations contain the drug in amorphous form. The goal of this study was to evaluate the robustness of the innovator product and five generic formulations to crystallization following storage at stress conditions.

Methods

Products were purchased from a pharmacy and stored at 40°C/75% relative humidity (RH), open dish conditions. Crystallinity was determined using X-ray diffraction. The quantity of the ingredients in the formulations were determined using different approaches and the various factors that might cause instability in the formulations were studied.

Results

After 4 weeks of open dish storage at 40°C/75% RH, one of the generic formulations showed evidence of tacrolimus crystallization. Further investigations revealed batch-to-batch variations in crystallization tendency with the extent of crystallinity varying between 50 and 100% for different batches. Crystallization was also observed at lower storage temperatures (30°C) when the RH was maintained at 75%. It was found that crystallization could be induced in a model formulation by wet granulating an ethanolic solution of the drug with lactose and drying at 60–70°C followed by exposure to stress conditions.

Conclusions

It seems probable that the generic that was susceptible to crystallization contains amorphous drug physically mixed with polymeric excipients, rather than as an amorphous solid dispersion. This study highlights the importance of considering the manufacturing process on the stability of the resultant amorphous product.

     

Nano Composite Emulsion for Sustained Drug Release and Improved Bioavailability

Purpose

To propose a novel composite nanoemulsion formulation that contains no surfactant, but offers great stability and improved oral absorption capabilities.

Methods

The nanoemulsions were prepared by dispersing the oil phase into aqueous solutions containing different amounts of the PMMA/silica composite nanoparticles. The stability was tested under extreme conditions. The structure features of the nanoemulsion droplets were investigated using Electron microscope. The in vitro drug release and in vivo drug absorption profiles after oral administration were investigated using Cyclosporin A as a model drug.

Results

The composite nanoemulsion demonstrated great stability under various disruptive conditions. Electron microscopy studies indicated the existence of internal and surface domains in the nano-droplet structure. In vitro drug release and in vivo uptake characterizations also confirmed the unique interfacial properties of such nanoemulsion structures.

Conclusions

The novel nanoemulsion formulation may have modulated drug release profiles and alternative oral absorption mechanisms, which could offer significant advantages compared to traditional emulsion formulations.     

Improving Viscosity and Stability of a Highly Concentrated Monoclonal Antibody Solution with Concentrated Proline

Purpose

To explain the effects of the osmolyte proline on the protein-protein interactions (PPI), viscosity and stability of highly concentrated antibody solutions in contrast to other neutral osmolytes.

Methods

The viscosity of ~225 mg/mL mAb solutions was measured with proline, glycine and trehalose as a function of pH and co-solute concentration up to 1.3 M. The stability was assessed via turbidity as well as size exclusion chromatography after 4 weeks storage at 40°C. The PPI strength was assessed qualitatively via the high concentration diffusion rate by dynamic light scattering.

Results

Increasing proline significantly reduced the mAb viscosity and increased the colloidal stability at pH 6, but not at pH 5 further from the mAb pI. In contrast, glycine and trehalose did not improve the viscosity nor stability. The normalized diffusion coefficient at high concentration, which is inversely proportional to the attractive PPI strength, increased with proline concentration but decreased with increasing glycine.

Conclusions

Proline demonstrated greater efficacy for improving mAb viscosity and stability in contrast to glycine and trehalose due to its amphipathic structure and partial charge on the pyrrolidine side chain. These properties likely allow proline to screen the attractive electrostatic and hydrophobic interactions that promote self-association and high viscosities. Binary proline-histidine formulations also demonstrated greater viscosity reduction effects than histidine alone at the same total co-solute concentration, while maintaining a lower total solution osmolarity.

     

Solid Lipid Particles for Oral Delivery of Peptide and Protein Drugs II – The Digestion of Trilaurin Protects Desmopressin from Proteolytic Degradation

Purpose

To investigate the in vitro release and degradation of desmopressin from saturated triglyceride microparticles under both lipolytic and proteolytic conditions.

Methods

The release of desmopressin from different solid lipid microparticles in the absence and presence of a microbial lipase and protease was determined. Trilaurin (TG12), trimyristin (TG14), tripalmitin (TG16), and tristearin (TG18) were used as lipid excipients to produce solid lipid microparticles.

Results

In the presence of lipase, the rate of drug release from different lipid particles was in the order of TG14 > TG16 > TG18, which is the same rank order as the lipid degradation rate. A reverse rank order was found for the protection of desmopressin from enzymatic degradation due to spatial separation of desmopressin from the protease. TG12 accelerated the release of desmopressin from all lipid particles when added as either drug-free microparticles to the lipolysis medium or incorporated in TG16 particles. Additionally, TG12 particles protected desmopressin from degradation when present in the lipolysis medium with the other lipid microparticles.

Conclusions

TG12 is a very interesting lipid for oral lipid formulations containing peptides and proteins as it alters release and degradation of the incorporated desmopressin. The present study demonstrates the possibility of bio-relevant in vitro evaluation of lipid-based solid particles.     

Ocular Disposition of the Hemiglutarate Ester Prodrug of ∆9-Tetrahydrocannabinol from Various Ophthalmic Formulations

Purpose

The overall goal of this project is to enhance ocular delivery of ?⁹-Tetrahydrocannabinol (THC) through the topical route.

Methods

Solubility, stability and in vitro transcorneal permeability of the relatively hydrophilic hemiglutarate ester derivative, THC-HG, was studied in the presence of surfactants. The solutions were characterized with respect to micelle size, zeta potential and solution viscosity. In vivo studies were carried out in New Zealand albino rabbits. A previously reported promising THC-HG ion-pair formulation was also studied in vivo.

Results

Aqueous solubility and stability and in vitro transcorneal permeability of THC-HG was enhanced significantly in the presence of surfactants. THC levels in the ocular tissues (except cornea) were found to be below detection limits from mineral oil, surfactant or emulsion based formulations containing THC. In contrast, micellar and ion pair based THC-HG formulations produced significantly higher total THC concentrations in the anterior ocular chamber.

Conclusion

In this study, although delivery of THC to the anterior chamber ocular tissues could be significantly increased through the prodrug and formulation approaches tested, further studies are needed to increase penetration to the back-of-the eye.     

Inhalable Sustained-Release Formulation of Glucagon: In Vitro Amyloidogenic and Inhalation Properties, and In Vivo Absorption and Bioactivity

Purpose

The present study aimed to develop novel glucagon-loaded PLGA nanospheres without cytotoxic fibril formation for chronic glucagon replacement therapy.

Methods

Glucagon-loaded nanospheres (GLG/NS) were prepared by an emulsion solvent diffusion method in oil, and a respirable powder formulation (GLG/NS-RP) was prepared with a jet mill. Physicochemical and inhalation properties of GLG/NS-RP were characterized, and pharmacokinetic behavior and hyperglycemic effect of intratracheally instilled GLG/NS-RP were evaluated in rats.

Results

Although preparation of GLG/NS using glucagon solution at concentrations over 10?mg/mL led to significant formation of cytotoxic glucagon aggregates, glucagon solution at less than 5?mg/mL did not cause structural changes. Drug release behavior of GLG/NS showed a biphasic pattern with an initial burst and slow diffusion. Laser diffraction and cascade impactor analyses of GLG/NS-RP suggested high dispersion and deposition in the respiratory organs with a fine particle fraction of 20.5%. After the intratracheal administration of the GLG/NS-RP (200???g glucagon/kg) in rats, glucagon was released in a sustained manner, leading to sustained hyperglycemic effects compared with those of normal glucagon powder.

Conclusion

These data would suggest a therapeutic benefit of the newly developed GLG/NS-RP as an alternative to the injection form of glucagon currently used.     

Rapid Assessment of Homogeneity and Stability of Amorphous Solid Dispersions by Atomic Force Microscopy—From Bench to Batch

Purpose

To verify the robustness and fundamental value of Atomic Force Microscopy (AFM) and AFM-based assays to rapidly examine the molecular homogeneity and physical stability of amorphous solid dispersions on Hot-Melt-Extrudates.

Methods

Amorphous solid dispersions were prepared with a Hot-Melt Extruder (HME) and profiled by Raman Microscopy and AFM following a sequential analytical routine (Multi-Scale-Imaging-of-Miscibiliy (MIMix)). Extrudates were analyzed before and after incubation at elevated temperature and humidity. The data were compared with published results as collected on miniaturized melt models. The value of molecular phase separation rates for long term stability prediction was assessed.

Results

Data recorded on the extrudates are consistent with those published, and they can be compared side by side. Such direct data comparisons allow the identification of possible sources of extrudate heterogeneities. The surface roughness analysis of fracture-exposed interfaces is a novel quantitative way to trace on the nanometer scale the efficiencies of differently conducted HME-processes. Molecular phase separation rates are shown to be relevant for long term stability predictions.

Conclusions

The AFM-based assessment of API:excipient combinations is a robust method to rapidly identify miscible and stable solid dispersions in a routine manner. It provides a novel analytical tool for the optimization of HME processes.     

Development of Solid Self-Emulsifying Drug Delivery System (SEDDS) I: Use of Poloxamer 188 as Both Solidifying and Emulsifying Agent for Lipids

Purpose

To develop solid self-emulsifying drug delivery systems (SEDDS) for lipids using poloxamer 188 as both solidifying and emulsifying agents.

Methods

Mixtures of various lipids with poloxamer 188 and PEG 8000 were prepared at ~75°C. The molten mixtures, with and without dissolved drugs (fenofibrate and probucol), were then cooled to room temperature. When solids formed, they were characterized by powder XRD, DSC, microscopy using cross-polarization and confocal fluorescence techniques, dispersion test in water and particle size analysis of dispersions.

Results

When mixed with poloxamer 188 or PEG 8000, lipids consisting of monoesters of fatty acids with glycerol or propylene glycol formed solid systems, but not di- and tri-esters, which showed phase separation. Added to water, the solid systems containing poloxamer 188 started to disperse in water forming oil globules of 200–600?nm. No emulsification of lipids was observed from solids containing PEG 8000, indicating that the surfactant property of poloxamer 188 was responsible for emulsification. Powder XRD, DSC and microscopic examination revealed that poloxamer 188 and PEG 8000 maintained their crystallinity in solid systems, while the lipids were interspersed in between crystalline regions. The drug remained solubilized in the lipid phase.

Conclusions

A novel solid SEDDS is developed where the drug can be solubilized in liquid lipids and then the lipidic solution can be converted to solid mass by dispersing into the microstructure of poloxamer 188.     

Effects of Ionic Strength and Sugars on the Aggregation Propensity of Monoclonal Antibodies: Influence of Colloidal and Conformational Stabilities

Purpose

To develop a general strategy for optimizing monoclonal antibody (MAb) formulations.

Methods

Colloidal stabilities of four representative MAbs solutions were assessed based on the second virial coefficient (B ₂) at 20°C and 40°C, and net charges at different NaCl concentrations, and/or in the presence of sugars. Conformational stabilities were evaluated from the unfolding temperatures. The aggregation propensities were determined at 40°C and after freeze–thawing. The electrostatic potential of antibody surfaces was simulated for the development of rational formulations.

Results

Similar B ₂ values were obtained at 20°C and 40°C, implying little dependence on temperature. B ₂ correlated quantitatively with aggregation propensities at 40°C. The net charge partly correlated with colloidal stability. Salts stabilized or destabilized MAbs, depending on repulsive or attractive interactions. Sugars improved the aggregation propensity under freeze–thaw stress through improved conformational stability. Uneven and even distributions of potential surfaces were attributed to attractive and strong repulsive electrostatic interactions.

Conclusions

Assessment of colloidal stability at the lowest ionic strength is particularly effective for the development of formulations. If necessary, salts are added to enhance the colloidal stability. Sugars further improved aggregation propensities by enhancing conformational stability. These behaviors are rationally predictable according to the surface potentials of MAbs.