Comparing nitric acid treatment and microwave digestion for efficiency of metal extraction from bioprocess samples.

Metal ions may act as enzyme cofactors and influence the kinetics of biochemical reactions that may also influence the biological production of therapeutic proteins and quality attributes such as glycosylation. Because sample preparation is a significant step in the reliable analysis of metals, we compared two sample preparation procedures for metal analysis of bioreactor culture media samples by ICP-MS: (i) samples were diluted in 2 % nitric acid (treatment with nitric acid, TNA); and (ii) samples were mixed with equal volume of 5 % nitric acid and closed vessel digestion was performed in a microwave (closed vessel digestion, CVD). In the comparison of extraction efficiencies between TNA and CVD procedures, CVD showed better extraction for Ca and Cu among bulk metals (∼30 %) and for Ni among the trace metals (∼65 %) for the bioreactor broth supernatant samples. For the cell pellet samples, the CVD procedure was found to be better for extraction of Fe (∼65 % more) among bulk metals, Zn (∼20 % more) among minor metals and Co (∼60 % more) and Ni (∼45 % more) among trace metals. Differences between the two procedures were less than 10 % and TNA was better for all other metals quantified from both supernatant samples and cell pellet samples. The current study helps bring more clarity to the methodology on comprehensive metal analysis to monitor and maintain trace metal content for biologics production.

Multicentric analysis of the perceptions and knowledge of digital health amongst undergraduate medical students.

INTRODUCTION: Digital health (DH) is continuously evolving by use of information and communications technology to improve healthcare provision, thereby reshaping systems and clinical practices. Recent studies identified an overwhelming lack of awareness of DH within the profession. This study aimed to analyse student perceptions and knowledge of DH to assess confidence in its use to develop greater DH awareness and literacy. METHODS: Students enrolled in undergraduate medical degrees were invited to take part in an online survey assessing aspects of DH including demography, familiarity, attitudes, level of knowledge and confidence. Anonymised data was collated and subsequently analysed to review DH awareness. RESULTS: A total of 143 students participated from nine British universities with 28.7% of respondents admitting low levels of familiarity of DH concepts. Students anticipated negative repercussions of DH including reduced data security (42.7%) and deterioration in doctor-patient relationship (30%); while improvements in healthcare access and health-outcomes are expected by 89.5% and 68.5%, respectively. 71.4% of participants believed they had minimal experience of exposure to DH and 76% believed they did not possess the necessary skills to utilise DH. Only 3.5% of students had some exposure to DH teaching during their course. CONCLUSION: There is an important requirement to address the lack of knowledge and exposure of students to DH, particularly as the world targets the COVID-19 pandemic. DH is forming the basis of the 'new normal' in healthcare, however the full potential of DH cannot be achieved unless there is an increase in its teaching incorporated into medical school curricula.

Impacts on product quality attributes of monoclonal antibodies produced in CHO cell bioreactor cultures during intentional mycoplasma contamination events.

A mycoplasma contamination event in a biomanufacturing facility can result in costly cleanups and potential drug shortages. Mycoplasma may survive in mammalian cell cultures with only subtle changes to the culture and penetrate the standard 0.2-µm filters used in the clarification of harvested cell culture fluid. Previously, we reported a study regarding the ability of Mycoplasma arginini to persist in a single-use, perfusion rocking bioreactor system containing a Chinese hamster ovary (CHO) DG44 cell line expressing a model monoclonal immunoglobulin G 1 (IgG1) antibody. Our previous work showed that M. arginini affects CHO cell growth profile, viability, nutrient consumption, oxygen use, and waste production at varying timepoints after M. arginini introduction to the culture. Careful evaluation of certain identified process parameters over time may be used to indicate mycoplasma contamination in CHO cell cultures in a bioreactor before detection from a traditional method. In this report, we studied the changes in the IgG1 product quality produced by CHO cells considered to be induced by the M. arginini contamination events. We observed changes in critical quality attributes correlated with the duration of contamination, including increased acidic charge variants and high mannose species, which were further modeled using principal component analysis to explore the relationships among M. arginini contamination, CHO cell growth and metabolites, and IgG1 product quality attributes. Finally, partial least square models using NIR spectral data were used to establish predictions of high levels (≥104 colony-forming unit [CFU/ml]) of M. arginini contamination, but prediction of levels below 104 CFU/ml were not reliable. Contamination of CHO cells with M. arginini resulted in significant reduction of antibody product quality, highlighting the importance of rapid microbiological testing and mycoplasma testing during particularly long upstream bioprocesses to ensure product safety and quality.

Zinc supplementation improves the harvest purity of ß-glucuronidase from CHO cell culture by suppressing apoptosis.

The variability of trace metals in cell culture media is a potential manufacturing concern because it may significantly affect the production and quality of therapeutic proteins. Variability in trace metals in CHO cell culture has been shown to impact critical production metrics such as cell growth, viability, nutrient consumption, and production of recombinant proteins. To better understand the influence of excess supplementation, zinc and copper were initially supplemented with 50-µM concentrations to determine the impact on the production and quality of ß-glucuronidase, a lysosomal enzyme, in a parallel bioreactor system. Ethylenediaminetetraacetic acid (EDTA), a metal chelator, was included as another treatment to induce a depletion of trace metal bioavailability to examine deficiency. Samples were drawn daily to monitor cell growth and viability, nutrient levels, ß-glucuronidase activity, and trace zinc flux. Cell cycle analysis revealed the inhibition of sub-G0/G1 species in zinc supplemented cultures, maintaining higher viability compared to the control, EDTA-, and copper-supplemented cultures. Enzyme activity analysis in the harvests revealed higher specific activity of ß-glucuronidase in reactors supplemented with zinc. A confirmation run was conducted with supplementations of zinc at concentrations of 50, 100, and 150 µM. Further cell cycle analysis and caspase-3 analysis demonstrated the role of zinc as an apoptosis suppressor responsible for the enhanced harvest purity of ß-glucuronidase from zinc-supplemented bioreactors.

Evaluation of Abuse-Deterrent Characteristics of Tablets Prepared via Hot-Melt Extrusion.

In this study, the effect of formulation variables and process parameters on the abuse-deterrent (AD) characteristics of a matrix tablet manufactured using hot-melt extrusion (HME) was investigated. The formulation variables included polyethylene oxide (PEO) grades and its input level, while the HME process parameters varied were barrel temperature profile and die diameter. Depending on the diameter of the extrudate (2.5 mm or 5.0 mm), two different downstream processes were used to prepare the tablets: cryo-milling followed by compression for the 2.5 mm extrudate, and cutting followed by compression for the 5.0 mm extrudate. A D-optimal statistical design was used to evaluate the impact of formulation and process parameters on various responses, including tablet physical strength, particle size after manipulation, syringeability and injectability, solution viscosity, extractability in solvents, and dissolution rates. It was found that the post-HME extrusion processing method played a critical role in affecting the AD characteristics of abuse-deterrent formulations, likely through changing the tablet compactability and porosity. When the extrudates were cryo-milled-compressed, the tablets could be readily manipulated by milling, which led to high degree of extractability. Under high alcohol concentration, burst drug release was observed for the tablets compressed from cryo-milled extrudates. Additionally, heat exposure during HME process caused significant drop in PEO solution viscosity, likely due to thermal degradation.

Design, synthesis and DSSC performance of o-fluorine substituted phenylene spacer sensitizers: effect of TiO2 thickness variation.

The influence of TiO2 film thickness on the performance of DSSCs with a new series of dyes having ortho-fluorine substituted phenyl spacers and different donor moieties is reported. Optical, electrochemical, molecular orbital and photovoltaic properties were studied by varying the TiO2 thickness (9 and 12 µm) using these dyes. The thickness variation of TiO2 films had a significant effect on the open circuit voltage (Voc), short circuit current (Jsc) and efficiency. The Jsc and Voc of dye 1b with a TiO2 film thickness of 12 µm (8.91 mA cm-2 and 0.63 V) were larger than those of the 9 µm film thickness device (8.40 mA cm-2 and 0.57 V). This could be due to the variation in the thickness of the TiO2 film. However, at an optimized thickness of the TiO2 film (12 µm), 1b exhibited the highest power conversion efficiency (η) of 4.0% (average 3.6%). This highest efficiency value for 1b from 3.3% to 4.0% without using any co-absorbents was solely based on changing the thickness of the TiO2 film. In addition 1b had a planar structure, whereas dyes 2b and 3b had three and two dimensional structures. The optimized geometry calculation of o-fluoro phenyl π-spacer dyes was ascertained by density functional theory (DFT) using the B3LYP/631G(d,p) basis set. These results reveal that dye 1b has higher efficiency due to the deeper HOMO level and it exhibited better charge transfer from donor to acceptor, compared to the other dyes.

Comparison of Univariate and Multivariate Models of ¹³C SSNMR and XRPD Techniques for Quantification of Nimodipine Polymorphs.

The focus of the present investigation was to explore the use of solid-state nuclear magnetic resonance ((13)C ssNMR) and X-ray powder diffraction (XRPD) for quantification of nimodipine polymorphs (form I and form II) crystallized in a cosolvent formulation. The cosolvent formulation composed of polyethylene glycol 400, glycerin, water, and 2.5% drug, and was stored at 5°C for the drug crystallization. The (13)C ssNMR and XRPD data of the sample matrices containing varying percentages of nimodipine form I and form II were collected. Univariate and multivariate models were developed using the data. Least square method was used for the univariate model generation. Partial least square and principle component regressions were used for the multivariate models development. The univariate models of the (13)C ssNMR were better than the XRPD as indicated by statistical parameters such as correlation coefficient, R (2), root mean square error, and standard error. On the other hand, the XRPD multivariate models were better than the (13)C ssNMR as indicated by precision and accuracy parameters. Similar values were predicted by the univariate and multivariate models for independent samples. In conclusion, the univariate and multivariate models of (13)C ssNMR and XRPD can be used to quantitate nimodipine polymorphs.

Adoption of hooped-battens in cold-formed steel built-up columns for superior axial performance.

Previous research on cold-formed steel (CFS) battened columns has identified the critical factors influencing their performance and accordingly, their limiting values for improved performance have been recommended. However, these studies involved connecting battens to the chords (channels) via their flanges, leaving the slenderest component disconnected from the web. This study introduces a novel hooped-batten (tubular-element) that links both webs and flanges of the chords together, thereby improving the structural integrity of the built-up system and curtailing the half-wave buckling length in the webs. As a result, axial strength and stability in these built-up columns may improve adequately. Firstly, a numerical model of a conventional CFS battened column was developed in ABAQUS and verified against test results on the same reported in literature. Afterward, the validated model was used to simulate the behaviour of CFS built-up columns with hooped-battens. Two key parameters i.e., unbraced chord slenderness and overall column slenderness were varied to explore their influence on the axial behaviour of built-up columns in terms of peak strengths, failure modes and load-displacement characteristics. The performance of the hooped-battened columns was compared with the identical conventional battened columns, which reflects that the former exhibits superior strength and stability characteristics over the latter.

Axial compression tests on CFRP strengthened CFS plain angle short columns.

A comprehensive test program was performed to experimentally investigate the effect of CFRP strengthening on the axial strength and stability of CFS plain angle short columns subjected to monotonic axial compression. A total of 28 specimens were tested by varying the CFRP strengthening configurations for different column heights. Both uni-directional (CF_UD) and bi-directional (CF_BD) CFRP were considered. The influence of various parameters such as the type of CFRP, fiber orientation, and number of CFRP layers was investigated and discussed in detail. For single layer (ply) of CFRP, CF_UD-0° strengthening configuration resulted in maximum increase of axial capacity by 58.33% and 45.72% (in comparison to bare steel specimens), corresponding to 0.5 m and 1.0 m column lengths respectively. All the bare steel and skin-strengthened specimens failed predominantly due to torsional-flexural buckling mode. Additional layer of CFRP wrapping was found to enhance the axial capacity further and CF_UD-0°/BD was found to possess greater capacity in the case of double layer of CFRP. Adopting cardboard in-fill in addition to CF_UD-0° wrap has prevented the torsional mode of buckling and resulted in a peak increase of axial capacity by 192.55% and 240.61% corresponding to 500 mm and 100 mm long specimens, respectively.

Nitrosamine mitigation: NDMA impurity formation and its inhibition in metformin hydrochloride tablets.

The mitigation of nitrosamine formation in drug products has been studied and approaches such as using formulations with pH modifiers and antioxidants have been shown to decrease the formation of nitrosamines. However, more studies are needed to explore the effectivness of mitigation strategies with different drug models and formulations. The primary objective of this work was to assess the role of different antioxidants and pH modifiers in tablet formulations to mitigate the formation of NDMA, prepared in-house, using metformin hydrochloride as a model drug. A study design for manufacturing metformin hydrochloride formulations was created to evaluate potential mitigation stratigies. The formulations were prepared by wet granulation that included a sodium nitrite spike and various antioxidants such as ascorbic acid, caffeic acid and ferulic acid at various concentrations that may inhibit nitrosamine formation. The study design also included pH modifiers such as hydrochloric acid and sodium carbonate. The metformin hydrochloride formulations were placed under stability conditions that included humidity, temperature and time over a six month period. NDMA inhibition was found to be most effective in formulations with basic pH, followed by the addition of tested antioxidants with 0.1% concentrations in the formulations. All tested antioxidants showed complete mitigation in formulations with 0.5% and 1% concentrations. In summary, basic pH and the inclusion of antioxidants exhibited the potential to mitigate the formation of NDMA in metformin hydrochloride tablets.

Evaluating Adherence to Therapeutic Drug Monitoring Guidelines for Gentamicin in Neonatal Care: A Retrospective Study at the Maternity and Children's Hospital in Makkah.

In this study, we assess healthcare providers' adherence to therapeutic drug monitoring (TDM) guidelines for gentamicin in neonates. Conducted at the Maternity and Children's Hospital in Makkah, Saudi Arabia, from July 2020 to July 2022, it retrospectively analyzed the compliance of healthcare workers in managing neonates treated with gentamicin. Covering 410 neonates, primarily diagnosed with respiratory distress (56%) and sepsis (32%), the study revealed that while a majority of trough and peak levels conformed to guidelines, substantial deviations were noted in cases of respiratory distress. This underlines the necessity for targeted TDM strategies, particularly in managing respiratory distress in neonates, to ensure optimal treatment efficacy and safety. The findings urge stringent compliance with TDM guidelines, emphasizing personalized approaches in neonatal gentamicin therapy for improved healthcare outcomes.

Long-term river extent dynamics and transition detection using remote sensing: Case studies of Mekong and Ganga River.

River dynamics are currently comprehensively studied at either a bankline or reach-scale level. Monitoring large-scale and long-term river extent dynamics provides fundamental insights relevant to the impact of climatic factors and anthropogenic activities on fluvial geomorphology. This study analyzed the two most populous rivers, Ganga and Mekong, to understand the river extent dynamics using 32 years of Landsat satellite data (1990-2022) in a cloud computing platform. This study categorizes river dynamics and transitions using the combination of pixel-wise water frequency and temporal trends. This approach can demarcate the river channel stability, areas affected by erosion and sedimentation, and the seasonal transitions in the river. The results illustrate that the Ganga river channel is found to be relatively unstable and very prone to meandering and migration as almost 40 % of the river channel has been altered in the past 32 years. The seasonal transitions, such as lost seasonal and seasonal to permanent changes are more prominent in the Ganga river, and the dominance of meandering and sedimentation in the lower course is also illustrated. In contrast, the Mekong river has a more stable course with erosion and sedimentation observed at sparse locations in the lower course. However, the lost seasonal and seasonal to permanent changes are also dominant in the Mekong river. Since 1990, Ganga and Mekong rivers have lost approximately 13.3 % and 4.7 % of their seasonal water respectively, as compared to the other transitions and categories. Factors such as climate change, floods, and man-made reservoirs could all be critical in triggering these morphological changes.

Rapid Quantitation of Four Nitrosamine Impurities in Angiotensin Receptor Blocker Drug Substances.

Starting in July 2018, the FDA alerted patients and health care professionals to the recall of ARBs such as valsartan by several pharmaceutical companies because of their potential contamination with carcinogenic nitrosamine impurities, including: (1) N-nitrosodimethylamine (NDMA), (2) N-nitrosodiethylamine (NDEA), (3) N-nitrosoethylisopropylamine (NEIPA), (4) N-nitrosodiisopropylamine (NDIPA), (5) N-nitrosodibutylamine (NDBA) and (6) N-nitroso-N-methyl-4-aminobutyric acid (NMBA). The FDA initiated a laboratory investigation to develop analytical procedures to test multiple lots of marketed ARB drugs to determine the possible presence of carcinogenic impurities and, if present, quantitate the levels of these impurities. Here the FDA laboratory developed and validated an automated micro-solid phase extraction MS/MS method, where all the analytes are not separated prior to elution to the MS, to simultaneously quantify NEIPA, NDIPA, NDBA and NMBA in ARB drug substances with an instrument sample analysis time of 12 seconds. The method was validated according to the ICH Q2(R1) guideline, and was determined to be specific, accurate, precise and linear over the corresponding nitrosamine analytical ranges. The method has been successfully implemented to quantitate the four nitrosamine impurities in 129 generic losartan, valsartan, olmesartan, irbesartan and telmisartan drug substance samples from 32 lots; and 32 losartan and valsartan drug product samples from 6 lots.

Bumetanide as a Model NDSRI Substrate: N-nitrosobumetanide Impurity Formation and its Inhibition in Bumetanide Tablets.

Nitrosamine compounds are classified as potential human carcinogens, the origin of these impurities can be broadly classified in two categories, nitrosamine impurity found in drug products that are not associated with the Active Pharmaceutical Ingredient (API), such as N-nitrosodimethylamine (NDMA) or nitrosamine impurities associated with the API, such as nitrosamine drug substance-related impurities (NDSRIs). The mechanistic pathway for the formation of these two classes of impurities can be different and the approach to mitigate the risk should be tailored to address the specific concern. In the last couple of years number of NDSRIs have been reported for different drug products. Though, not the only contributing factor for the formation of NDSIRs, it is widely accepted that the presence of residual a nitrites/nitrates in the components used in the manufacturing of the drug products can be the primary contributor to the formation of NDSRIs. Approaches to mitigate the formation of NDSRIs in drug products include the use of antioxidants or pH modifiers in the formulation. The primary objective of this work was to evaluate the role of different inhibitors (antioxidants) and pH modifiers in tablet formulations prepared in-house using bumetanide (BMT) as a model drug to mitigate the formation of N-nitrosobumetanide (NBMT). A multi-factor study design was created, and several bumetanide formulations were prepared by wet granulation with and without sodium nitrite spike (100 ppm) and different antioxidants (ascorbic acid, ferulic acid or caffeic acid) at three concentrations (0.1%, 0.5% or 1% of the total tablet weight). Formulations with acidic and basic pH were also prepared using 0.1 N hydrochloric acid and 0.1 N sodium bicarbonate, respectively. The formulations were subjected to different storage (temperature and humidity) conditions over 6 months and stability data was collected. The rank order of N-nitrosobumetanide inhibition was highest with alkaline pH formulations, followed by formulations with ascorbic acid, caffeic acid or ferulic acid present. In summary, we hypothesize that maintaining a basic pH or the addition of an antioxidant in the drug product can mitigate the conversion of nitrite to nitrosating agent and thus reduce the formation of bumetanide nitrosamines.

Human visual consciousness involves large scale cortical and subcortical networks independent of task report and eye movement activity.

The full neural circuits of conscious perception remain unknown. Using a visual perception task, we directly recorded a subcortical thalamic awareness potential (TAP). We also developed a unique paradigm to classify perceived versus not perceived stimuli using eye measurements to remove confounding signals related to reporting on conscious experiences. Using fMRI, we discovered three major brain networks driving conscious visual perception independent of report: first, increases in signal detection regions in visual, fusiform cortex, and frontal eye fields; and in arousal/salience networks involving midbrain, thalamus, nucleus accumbens, anterior cingulate, and anterior insula; second, increases in frontoparietal attention and executive control networks and in the cerebellum; finally, decreases in the default mode network. These results were largely maintained after excluding eye movement-based fMRI changes. Our findings provide evidence that the neurophysiology of consciousness is complex even without overt report, involving multiple cortical and subcortical networks overlapping in space and time.

Dynamics of some common epidemics in Karachi, Pakistan.

OBJECTIVE: To examine the severity, frequency, monthly variability and grouping of some common epidemics and its relation to hygienic conditions and life style of the people in Karachi. METHODS: This ecological study was conducted from 2006 to 2009. Data was obtained from five different localities of Karachi. In each area, physician clinics were selected and questionnaire forms filled by professionals at the clinics, regarding health problems of patients. Multivariate analyses were used to summarize the data, for comparison and grouping the spread of epidemics. RESULTS: The severity of different epidemics varied among months and localities. The effective diseases potential areas with decreasing order were: Lines Area, Korangi, Malir, Metroville and Maymar. In all these areas cough, allergy, asthma, flu, fever and skin rashes were the widely distributed epidemics while the prevalence of other six epidemics prevailed to a lesser extent. Lines Area/Korangi and Malir/Metroville differed considerably with respect to prevalence of epidemics (P < 0.05) into a lesser, while Gulshan-e-Maymar was significantly different (P < 0.001) from the other four areas. Among four distinct groups i.e. 1) allergy/cough, 2) asthma/flu, 3) fever/skin rashes, 4) bronchitis, malaria, typhoid, diarrhoea, rhinitis and sinusitis, the first three groups were widely distributed. CONCLUSION: January was the most crucial month with highest number of patients. Certain epidemics were parallel in different areas with almost similar population size. Multivariate analysis disclosed the four distinct groups of epidemics in which first three groups were widely distributed.

Effect of iron addition on mAb productivity and oxidative stress in Chinese hamster ovary culture.

Trace metals play a critical role in the development of culture media used for the production of therapeutic proteins. Iron has been shown to enhance the productivity of monoclonal antibodies during Chinese hamster ovary (CHO) cell culture. However, the redox activity and pro-oxidant behavior of iron may also contribute toward the production of reactive oxygen species (ROS). In this work, we aim to clarify the influence of trace iron by examining the relationship between iron supplementation to culture media, mAb productivity and glycosylation, and oxidative stress interplay within the cell. Specifically, we assessed the impacts of iron supplementation on (a) mAb production and glycosylation; (b) mitochondria-generated free hydroxyl radicals (ROS); (c) the cells ability to store energy during oxidative phosphorylation; and (d) mitochondrial iron concentration. Upon the increase of iron at inoculation, CHO cells maintained a capacity to rebound from iron-induced viability lapses during exponential growth phase and improved mAb productivity and increased mAb galactosylation. Fluorescent labeling of the mitochondrial hydroxyl radical showed enhanced environments of oxidative stress upon iron supplementation. Additional labeling of active mitochondria indicated that, despite the enhanced production of ROS in the mitochondria, mitochondrial membrane potential was minimally impacted. By replicating iron treatments during seed train passaging, the CHO cells were observed to adapt to the shock of iron supplementation prior to inoculation. Results from these experiments demonstrate that CHO cells have the capacity to adapt to enhanced environments of oxidative stress and improve mAb productivity and mAb galactosylation with minimal perturbations to cell culture.

Antioxidant-Rich Woodfordia fruticosa Leaf Extract Alleviates Depressive-Like Behaviors and Impede Hyperglycemia.

Dhaiphul (Woodfordia fruticosa) is a frequently demanded plant in South-East Asian regions for its diverse medicinal values. This study was proposed to examine antioxidant, antidiabetic, and antidepressant potentials of methanol extract of W. fruticosa leaves (MEWF) and its derived n-hexane (NHFMEWF) and ethyl acetate (EAFMEWF) fractions through in vitro, in vivo, and computational models. Among test samples, MEWF and EAFMEWF contained the highest phenolic content and showed maximal antioxidant activity in DPPH radical scavenging and ferric reducing power assays. In comparison, NHFMEWF possessed maximum flavonoid content and a significantly potent α-amylase inhibitory profile comparable with positive control acarbose. In animal models of depression (forced swimming and tail suspension test), EAFMEWF and NHFMEWF demonstrated a dose-dependent antidepressant-like effect; explicitly, the depressive-like behaviors significantly declined in EAFMEWF-treated dosing groups in contrast to the control group. In the computational analysis, previously isolated flavonoid compounds from Dhaiphul leaves manifested potent binding affinity against several key therapeutic target proteins of diabetes and depressive disorders including α-amylase, serotonin transporter, dopamine transporter, and neuronal nitric oxide synthase with varying pharmacokinetics and toxicity profiles. This research's outcomes may provide potential dietary supplements for mitigating hyperglycemia, cellular toxicity, and depressive disorder.

In vitro physicochemical characterization and dissolution of brinzolamide ophthalmic suspensions with similar composition.

The quality of an ophthalmic suspension is crucial for its in vivo performance, and often impact product's effectiveness. An in-depth understanding of critical quality attributes (CQAs) of ophthalmic suspensions such as particle size distribution (PSD) and rheology, as well as the impact of these CQAs on product performance are important for successful product development, quality control, and regulatory approval. This study employed brinzolamide ophthalmic suspension, 1%, as a model ophthalmic product, and six batches were manufactured using an innovative planetary centrifugal milling (PCM) process. Three batches were manufactured to have distinctly different PSD. These three batches had qualitatively (Q1) and quantitatively (Q2) the same composition as the model drug product (i.e., Azopt), while the differences in PSD were introduced by changing only the manufacturing process parameters. On the other hand, changes in rheology were introduced by altering the input level of the viscosity enhancing polymer in the formulation. A systematic approach was employed to understand the relation between manufacturing process parameters, CQAs, and in vitro product performance. Among the evaluated CQAs, PSD, rheology, surface tension, and drug dissolution were found more sensitive to the changes in the manufacturing processes. Most notably, we developed a rapid dissolution method (completed within minutes) employing in-situ fiber optic UV dissolution system. This novel dissolution method mimics the environmental conditions of the eye such as dissolution under "non-sink" condition and under high shear (from blinking). The method was highly discriminatory to differences in the PSD in the suspension. This study also revealed an important relation between the PSD of the suspension and its rheology which originated as a result of an interaction at the molecular level between the solid drug particles and the viscosity enhancing polymers. These findings underscore the need to evaluate CQAs of the ophthalmic suspensions in concert rather than separately when comparing ophthalmic drug products and product performance.

Factors affecting the particle size distribution and rheology of brinzolamide ophthalmic suspensions.

Drug particle size distribution (PSD) and dispersion viscosity are two critical quality attributes that govern the performance of topical ophthalmic suspensions, such as suspension physical stability, ocular retention, and drug release characteristics.. An in-depth knowledge of the effects of formulation and manufacturing process on these critical quality attributes may facilitate the product and process development, quality control, as well as support regulatory policy and approval. The current study has investigated the effect of formulation and process parameters on the quality attributes of brinzolamide ophthalmic suspensions. In the first step, three milling techniques (probe sonication, microfluidization, and media milling with a planetary centrifugal mixer) were evaluated for manufacturing of brinzolamide suspension. Out of the three techniques, the planetary centrifugal media milling yielded the narrowest PSD and thus was considered the most viable lab-scale technique for this purpose. In the next step, various process parameters of media milling were evaluated using a central-composite experimental design. The independent variables included bead size, agitating intensity, and process time while the PSD of drug particles (D50) was the response variable. The effect of shear rate and shear time of the homogenization process and the concentration of carbomer on the rheological properties of the suspension were studied using a Box-Behnken design. Additionally, effects of sodium chloride and mannitol concentration on the rheological properties of the suspension was also investigated. Sodium chloride was found to exert a pronounced effect on rheology of the suspension. Despite variations in the carbomer concentration, a suspension of comparable rheology could be prepared by controlling the process parameters namely the shear rate and process time.