Understanding the impact of mannitol on physical stability and aerosolization of spray-dried protein powders for inhalation

Pulmonary delivery of protein-based therapeutics, including antibodies, is a promising option for treating respiratory diseases. Spray drying is a widely used method for producing dry powder formulations with mannitol being a commonly used excipient for these inhalation formulations. There is limited research available concerning the utilization of mannitol as an excipient in the spray drying of proteins and its impact on aerosol performance. This study highlights the importance to understand mannitol's potential role and impact in this context. To investigate the impact of mannitol on physical stability and aerosolization of spray-dried protein formulations, bovine serum albumin (BSA) was employed as a model protein and formulated with different concentrations of mannitol via spray drying. The spray-dried solids were characterized for their particle size using Malvern mastersizer and aerodynamic particle size using next generation impactor (NGI). Additionally, the solids were characterized with solid-state Fourier-transform infrared spectroscopy (ssFTIR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and solid-state nuclear magnetic resonance spectroscopy (ssNMR) to analyze the change in their secondary structure, crystallinity, particle morphology, and protein-excipient interaction, respectively. Size exclusion chromatography (SEC) was used to investigate changes in monomer content resulting from storage under stressed condition of 40 °C. Protein formulations containing more than 33 % mannitol by weight showed crystallization tendencies, causing an increase in monomer loss over time. ssNMR data also showed mixing heterogeneity of BSA and mannitol in the formulations with high mannitol contents. Futhermore, fine particle fraction (FPF) was found to decrease over time for the formulations containing BSA: Mannitol in the ratios of 2:1, 1:2, and 1:5, due to particle agglomeration induced by crystallization of mannitol. This study underscores the significant influence of excipients such as mannitol on the aerosol performance and storage stability of spray-dried protein formulations.

Ocular posterior segment microstructural and microvascular morphological changes in protein supplement-consuming bodybuilders

BACKGROUND

To determine the effects of protein supplement (whey protein powder (PP)) on retinal, choroidal and optic nerve head (ONH) microstructure and microvascular morphology in healthy bodybuilders.

METHODS

This cross-sectional study included 23 male adults (consumers, 23 right eyes) who had been routinely consuming whey PP for bodybuilding purposes for ≥ 3 months, and 21 age- and gender-matched healthy volunteers (non-consumers, 21 right eyes) who also attended the gym but did not consume any nutritional supplements. Participants underwent standard ocular exams, enhanced depth imaging optical coherence tomography (EDI OCT), and optical coherence tomography angiography (OCTA) after ≥ 8 h of rest and fasting.

RESULTS

Whey PP was consumed for a median of 9.5 (6-12) months. Whey PP consumers had a median age of 22 (21-22) years, while non-consumers had 21 (20-22) years (p = 0.067). Whey PP consumers had greater microstructural thickness than non-consumers, with subfoveal choroidal thickness (301.40 ± 38.91 versus 278.12 ± 33.58 µm; p = 0.035) being significantly different but not central macular thickness (270.55 ± 24.60 versus 265.85 ± 12.44 µm; p = 0.402). Despite a non-significant difference in superficial and deep capillary plexus vascular densities (VDs), whey PP consumers had relatively lower VDs than non-consumers in all macular regions (p > 0.05). Despite this, whey PP consumers displayed greater ONH VDs, as well as higher global RNFL thickness (116.75 ± 10.41 versus 114.50 ± 11.70 µm) than non-consumers (p > 0.05).

CONCLUSION

Protein supplements, particularly whey PPs, appear to be associated with different changes in the retina and choroid, as well as ONH microstructural and microvascular morphology, implying that paying attention to these clinical aspects when performing ocular tests in bodybuilders who consume nutritional supplements could be critical.

Transfer rates of Salmonella Typhimurium, Listeria monocytogenes, and a human norovirus surrogate impacted by macronutrient composition of food inks in 3D food printing systems

3D food printers (3DFPs) allow for the customization of the physiochemical properties of foods in new ways. Transfer kinetics of foodborne pathogens between surfaces and food inks have not been evaluated in 3DFPs. This study aimed to determine if the macromolecular composition of food inks would impact the transfer rate of foodborne pathogens from the stainless steel food ink capsule to the 3D printed food. Salmonella Typhimurium, Listeria monocytogenes, and a human norovirus surrogate, Tulane virus (TuV), were inoculated onto the interior surface of stainless steel food ink capsules and dried for 30 min. Subsequently, 100 g of one of the following prepared food inks was extruded: (1) pure butter, (2) a powdered sugar solution, (3) a protein powder solution, and (4) a 1:1:1 ratio of all three macromolecules. Pathogen enumeration was completed for both the soiled capsules and the printed food products and resulting transfer rates were estimated using a generalized linear model with quasibinomial errors. A significant two-way interaction effect was found between microorganism type and food ink type (P = 0.0002). Tulane virus was typically transferred the most, and no significant differences between L. monocytogenes and S. Typhimurium were observed for any food matrix or across food matrices. Among food matrices, the complex mixture transferred fewer microorganisms in all instances, while butter, protein, and sugar were all statistically indistinguishable. This research seeks to further develop the field of 3DFP safety and to advance the understanding of the role of macromolecular composition in pathogen transfer kinetics, which have not previously been explored in pure matrices.

Physicochemical, digestive and rheological properties of protein from tuna by subcritical dimethyl ether: Focus on process-related indexes

The process-related physicochemical, digestive and rheological properties of protein prepared by subcritical dimethyl ether extraction (SDEE) were comprehensively investigated and compared with those obtained by pH-shift, to study the industrial potential of SDEE. Two different materials from tuna (meat and liver) were studied in parallel, and SDEE had similar effects on the proteins in them. The protein component was almost unchanged before and after SDEE, while the content of water-soluble protein and alkali-soluble protein was substantially reduced and increased after pH-shift, respectively. We also found that SDEE had superior ability to pH-shift to conserve light metals, remove lipids and heavy metals, and maintain protein structure. Furthermore, SDEE-produced protein powders were easier for humans to digest, and their gelation and emulsification were also superior to those prepared by pH-shift. The aforementioned results suggest that SDEE can remove more impurities, and the obtained protein has outstanding potential in industrial applications.

Preparation of high concentration protein powder suspensions by milling of lyophilizates

Pharmaceutical formulations utilizing protein drugs as powders can be used as drug delivery systems in various ways. Besides powders for inhalation, another promising approach is their use as suspensions in non-aqueous liquids for subcutaneous administration providing high protein stability and good injectability. In this study protein powder suspensions were prepared using a swing-mill. Milling of lyophilizates containing a model monoclonal antibody in presence of the suspension vehicle was compared to cryogenic dry milling. Wet media milling led to injectable suspensions, but resulted in monomer loss and increase in protein aggregation. When the lyophilizates were cryogenic dry ball milled less aggregation and monomer loss were detected. Differences related to protein integrity were found for different process parameters, which were successfully optimized. If not cooled with liquid nitrogen, dry milling resulted in increased damage to the mAb. The type of polyol stabilizer, as well as the protein to stabilizer ratio, did not affect the preservation of protein integrity. As finding the right milling duration is time and resource intensive, a correlation between lyophilizate cake hardness and milling duration was established. Based on this approach high concentration lyophilizates were successfully micronized. Suspensions of cryogenic milled powders lead to clogging of 25G needles, which could be prevented by an additional sieving step. Depending on the suspension vehicle, low viscosity formulations (<10 mPa·s) even at high concentrations (≥100 mg/ml protein concentration) were obtained featuring good injectability.

Powder suspensions in non-aqueous vehicles for delivery of therapeutic proteins

Formulating biopharmaceuticals is a challenging task due to their complex and sensitive nature. Protein drugs are typically marketed either as an aqueous solution or as a lyophilizate. Usually aqueous solutions are preferred as neither drying nor reconstitution are required. But it may be unfeasible if the protein features low stability. An interesting alternative to avoid at least reconstitution are protein powder suspensions in non-aqueous vehicles. Such formulations combine the ready-to-use approach with the high protein stability in the solid state. Additionally, protein powder suspensions offer a potentially lower viscosity compared to aqueous solutions at high protein concentrations. Besides injection, other application routes might also benefit from the protein powder approach such as topical or inhalational delivery. Protein powders, which can be dispersed in the non-aqueous suspension vehicle, are usually prepared by spray-drying or freeze-drying with an additional milling step, but other techniques have also been described in literature. An ideal powder preparation technique results in minimum protein damage and yields particle sizes in the lower micrometre range and homogeneous particle size distribution enabling subcutaneous or intramuscular injection through hypodermic needles. As suspension vehicles traditional non-aqueous injectable liquids, such as plant oils, may be selected. But they show an inherent high viscosity, which can lead to unacceptable glide forces during injection. Furthermore, the vehicle should provide high product stability with respect to protein integrity and suspension resuspendability. This review will describe how proteins can be formulated as protein powder suspensions in non-aqueous vehicles for subcutaneous injection including potential vehicles, protein powder preparation techniques, protein and suspension physical stability, as well as the use in the field of high concentration protein formulations.

A human health risk assessment of heavy metal ingestion among consumers of protein powder supplements

Concerns have recently been raised about the presence of heavy metals in protein powder supplements following a Consumer Reports analysis of 15 protein powder products. The Consumer Reports study found that the average amounts of heavy metals in three servings of protein powder per day exceeded the maximum limits in dietary supplements proposed by U.S. Pharmacopeia. In a follow up to the Consumer Reports analysis, another study reported that 40 % of the 133 protein powder products they tested had elevated levels of heavy metals. The objective of this analysis was to determine whether the heavy metal concentrations reported in protein powder supplements posed any human health risks, based on the reported concentrations of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) in the protein powder. The US EPA reference doses (RfD) for As and Cd, and the EPA screening level for Hg were based on the most sensitive health endpoint which were used to calculate hazard quotients (HQs) for each metal. The 'worse-case scenario' assessment for each protein powder product was expressed as a cumulative hazard index (HI), which is the sum of HQs from each heavy metal. Additionally, we utilized the U.S. EPA's Adult Lead Methodology (ALM) model to estimate adult blood lead levels (BLLs), which were compared to the CDC BLL guidance value of 5 μg/dL. All models assumed one or three servings of protein powder per day. Our results indicate that the exposure concentrations of the studied metals do not pose an increased health risk (Hazard Index < 1). We noted that the protein powder HI was mainly driven by the As or Cd content in each product. Interestingly, the highest HI levels (which approached 1) were found in 'mass gain' type protein powder supplements, whereas the lowest calculated HI levels were in whey protein powders. Moreover, background Pb exposure was the primary contributor to estimated BLLs in adults, and all modeled BLLs were below 5 μg/dL. Overall, our results suggest that the typical intake of dietary supplements would not result in adverse health effects due to heavy metals.

Muscle building supplement use in Australian adolescent boys: relationships with body image, weight lifting, and sports engagement

Background

The extent and implications of muscle building protein supplement use among adolescents is relatively unknown. This study aimed to describe the prevalence of protein powder, creatine, and anabolic steroid use in a sample of 14–16 year-old boys in Australia, and the predictors of actual use, and intentions to use protein powder.

Methods

Data were obtained from questionnaires with Australian adolescent boys aged 14–16 years from one independent boy’s school in Melbourne (N = 237). Hierarchical linear and logistic regressions were used to determine the predictors of intentions, and actual use of protein powder.

Results

49.8% of boys reported current use of, and 62% intended to use protein powder; 8.4% used creatine, and 4.2% used anabolic steroids. Higher levels of drive for muscularity, participation in weight training, and playing a greater number of sports were significant predictors of higher current use and intentions to use protein powder, but age, BMI, body esteem, and ethnicity were not.

Conclusions

Prevalence of muscle building supplement use was relatively high among this adolescent population. This research has implications for intervention and prevention programs to educate young boys about muscle building supplements to reduce negative physical and psychological health effects of their use.

Generic and rapid determination of low molecular weight organic chemical contaminants in protein powder by using ultra-performance liquid chromatography-tandem mass spectrometry

A rapid, simple, and generic analytical method that could simultaneously determine 291 undesirable low molecular weight chemical contaminants from different drug families in protein powder, such as veterinary drugs and pesticides, etc, had been developed. This method comprised the extraction with acetonitrile-dimethyl sulfoxide (DMSO), clean-up through dispersive solid phase extraction (D-SPE) and low temperature filtration, and analysis by ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry at multiple-reaction monitoring mode. Acetonitrile-DMSO was more generic than acetonitrile or methanol for the extraction of large-scale organic chemical contaminants with different polarities in protein powder. Most interferences in the extract were eliminated by the combination of D-SPE and low temperature filtration, which simultaneously provided satisfactory recoveries of both hydrophobic and hydrophilic analytes. In particular, besides the purification function, the sorbent of D-SPE also played an important role in grinding samples to improve extraction efficiency during homogenization. This streamlined approach allowed the processes of extraction and the main purification were carried out in one-step, and dramatically reduced sample preparation turnaround times and solvent consumption. For quantification, matrix-fortified calibration curves showed competent linearity for most of the target compounds with linear regression coefficients (r) higher than 0.9900, except for two analytes. The limits of quantification ranged from 0.1 μg/kg to 50 μg/kg, which was usually sufficient to verify the compliance of products with legal tolerances. The average recoveries for spiked protein powder ranged from 65.6% to 142.2% with associated RSD values between 0.5% and 28.5%. For over 90% of the analytes, the recoveries were between 70% and 120% with RSD values in the range of 1%-15%. Applying this method in routine monitoring programs would drastically reduce both effort and time.

The glycation level of milk protein strongly modulates post-prandial lysine availability in humans

Industrial heat treatment of milk results in protein glycation. A high protein glycation level has been suggested to compromise the post-prandial rise in plasma amino acid availability following protein ingestion. In the present study, we assessed the impact of glycation level of milk protein on post-prandial plasma amino acid responses in humans. Fifteen healthy, young men (age 26 (SEM 1) years, BMI 24 (SEM 1) kg/m2) participated in this randomised cross-over study and ingested milk protein powder with protein glycation levels of 3, 20 and 50 % blocked lysine. On each trial day, arterialised blood samples were collected at regular intervals during a 6-h post-prandial period to assess plasma amino acid concentrations using ultra-performance liquid chromatography. Plasma essential amino acid (EAA) concentrations increased following milk protein ingestion, with the 20 and 50 % glycated milk proteins showing lower overall EAA responses compared with the 3 % glycated milk protein (161 (SEM 7) and 142 (SEM 7) v. 178 (SEM 9) mmol/l × 6 h, respectively; P ≤ 0·011). The lower post-prandial plasma amino acid responses were fully attributed to an attenuated post-prandial rise in circulating plasma lysine concentrations. Plasma lysine responses (incremental AUC) following ingestion of the 20 and 50 % glycated milk proteins were 35 (SEM 4) and 92 (SEM 2) % lower compared with the 3 % glycated milk protein (21·3 (SEM 1·4) and 2·8 (SEM 0·7) v. 33·3 (SEM 1·7) mmol/l × 6 h, respectively; P < 0·001). Milk protein glycation lowers post-prandial plasma lysine availability in humans. The lower post-prandial availability of lysine following ingestion of proteins with a high glycation level may compromise the anabolic properties of a protein source.