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1.
Mol Pharm ; 21(3): 1321-1333, 2024 Mar 04.
Article in English | MEDLINE | ID: mdl-38334418

ABSTRACT

Attractive self-interactions and reversible self-association are implicated in many problematic solution behaviors for therapeutic proteins, such as irreversible aggregation, elevated viscosity, phase separation, and opalescence. Protein self-interactions and reversible oligomerization of two Fc-fusion proteins (monovalent and bivalent) and the corresponding fusion partner protein were characterized experimentally with static and dynamic light scattering as a function of pH (5 and 6.5) and ionic strength (10 mM to at least 300 mM). The fusion partner protein and monovalent Fc-fusion each displayed net attractive electrostatic self-interactions at pH 6.5 and net repulsive electrostatic self-interactions at pH 5. Solutions of the bivalent Fc-fusion contained higher molecular weight species that prevented quantification of typical interaction parameters (B22 and kD). All three of the proteins displayed reversible self-association at pH 6.5, where oligomers dissociated with increased ionic strength. Coarse-grained molecular simulations were used to model the self-interactions measured experimentally, assess net self-interactions for the bivalent Fc-fusion, and probe the specific electrostatic interactions between charged amino acids that were involved in attractive electrostatic self-interactions. Mayer-weighted pairwise electrostatic energies from the simulations suggested that attractive electrostatic self-interactions at pH 6.5 for the two Fc-fusion proteins were due to cross-domain interactions between the fusion partner domain(s) and the Fc domain.


Subject(s)
Amino Acids , Antibodies, Monoclonal , Antibodies, Monoclonal/chemistry , Dynamic Light Scattering , Osmolar Concentration , Hydrogen-Ion Concentration
2.
J Pharm Sci ; 112(11): 2778-2782, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37478972

ABSTRACT

Biological therapeutics are major contributors to the pharmaceutical pipeline and continue to grow in sales and scope. Additionally, the field's understanding of cancer biology has advanced such that biopharmaceuticals can harness the power of the immune system for oncology treatments. Several of these novel therapeutics are engineered versions of naturally occurring proteins designed to improve therapeutic properties including potency, target engagement and half-life extension. Cytokines, such as interferons and interleukins, are a broad class of signaling proteins which modulate the body's immune response; engineered cytokines have entered the clinic as promising new immuno-oncology therapies. While these therapies hold great promise, their additional structural complexity introduces analytical challenges, and traditional analytical platforms may be ill-suited to effectively assess product development risks. Further, the pharmaceutical industry relies on streamlining approaches for high-throughput experimentation to achieve speed and efficiency for the discovery and development of new modalities. These demands necessitate the use of state-of-the-art techniques to rapidly characterize these new modalities and guide process development and optimization. Matrix Assisted Laser Desorption Ionization Mass Spectrometry (MALDI-MS) is a rapid, sensitive and automatable technique amenable for high-throughput analysis of proteins. In this work, we have developed an automated MALDI-MS platform to prepare, acquire and analyze molecular degradation in engineered PEGylated cytokines formulation samples. This orthogonal technique integrated seamlessly with current developability risk assessment workflows, ultimately enabling selection of a final formulation strategy for clinical development.

3.
Nat Commun ; 12(1): 6055, 2021 10 18.
Article in English | MEDLINE | ID: mdl-34663813

ABSTRACT

COVID-19 caused by the SARS-CoV-2 virus has become a global pandemic. 3CL protease is a virally encoded protein that is essential across a broad spectrum of coronaviruses with no close human analogs. PF-00835231, a 3CL protease inhibitor, has exhibited potent in vitro antiviral activity against SARS-CoV-2 as a single agent. Here we report, the design and characterization of a phosphate prodrug PF-07304814 to enable the delivery and projected sustained systemic exposure in human of PF-00835231 to inhibit coronavirus family 3CL protease activity with selectivity over human host protease targets. Furthermore, we show that PF-00835231 has additive/synergistic activity in combination with remdesivir. We present the ADME, safety, in vitro, and in vivo antiviral activity data that supports the clinical evaluation of PF-07304814 as a potential COVID-19 treatment.


Subject(s)
COVID-19 Drug Treatment , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus Protease Inhibitors/administration & dosage , Indoles/administration & dosage , Leucine/administration & dosage , Pyrrolidinones/administration & dosage , Adenosine Monophosphate/administration & dosage , Adenosine Monophosphate/adverse effects , Adenosine Monophosphate/analogs & derivatives , Adenosine Monophosphate/pharmacokinetics , Alanine/administration & dosage , Alanine/adverse effects , Alanine/analogs & derivatives , Alanine/pharmacokinetics , Animals , COVID-19/virology , Chlorocebus aethiops , Coronavirus 229E, Human/drug effects , Coronavirus 229E, Human/enzymology , Coronavirus Protease Inhibitors/adverse effects , Coronavirus Protease Inhibitors/pharmacokinetics , Disease Models, Animal , Drug Design , Drug Synergism , Drug Therapy, Combination , HeLa Cells , Humans , Indoles/adverse effects , Indoles/pharmacokinetics , Infusions, Intravenous , Leucine/adverse effects , Leucine/pharmacokinetics , Mice , Pyrrolidinones/adverse effects , Pyrrolidinones/pharmacokinetics , Severe acute respiratory syndrome-related coronavirus/drug effects , Severe acute respiratory syndrome-related coronavirus/enzymology , SARS-CoV-2/drug effects , SARS-CoV-2/enzymology , Vero Cells
4.
BMC Public Health ; 21(1): 1091, 2021 06 07.
Article in English | MEDLINE | ID: mdl-34098911

ABSTRACT

BACKGROUND: The aim was to identify the most important determinants of practice for the implementation of person-centered tools which enhance work participation for patients with chronic health conditions. METHODS: A mixed-method study was conducted consisting of semi-structured interviews, a focus group and a survey. Various stakeholders were involved including (representatives of) workers with chronic health conditions, insurance physicians, occupational physicians, other healthcare professionals, researchers, employers, and policymakers. The semi-structured interviews were performed to identify implementation determinants, followed by a focus group to validate resulting determinants. To conclude, a survey was conducted to select the most important implementation determinants through prioritization by ranking the order of importance. The Tailored Implementation of Chronic Diseases checklist (TICD) was used as concept-driven coding frame for the qualitative analysis of the interviews and focus group. The self-developed survey was based on the domains of the TICD. The survey was analyzed by frequency count of first ranking of determinants per and between domains of the TICD. RESULTS: Various stakeholders participated (N = 27) in the interviews and focus group. The qualitative data retrieved yielded a list of determinants with additional in-depth themes according to the TICD. For the selection of the most important determinants, a survey with 101 respondents was conducted, consisting of occupational physicians, insurance physicians and workers with a chronic health condition. From the seven domains of the TICD, respondents emphasized the importance of taking into account the needs and factors associated with workers with a chronic health condition as this determinant ranked highest. Taking into account the individual needs and wishes of workers was mentioned to enable successful implementation, whereas stress of the workers was indicated to impede implementation. Other important determinants included 'being able to work with the tools' in terms of time and usability or 'cognitions, beliefs and attitudes of occupational and insurance physicians' to be able to use the tools. CONCLUSION: This study identified the most important determinants from the perspective of various stakeholders involved in the implementation of client-centered tools in occupational health for workers with chronic health conditions. Furthermore, by prioritizing the most important determinants, targeted implementation strategies can be developed.


Subject(s)
Checklist , Research Design , Chronic Disease , Focus Groups , Health Personnel , Humans , Qualitative Research
5.
bioRxiv ; 2021 Feb 12.
Article in English | MEDLINE | ID: mdl-32935104

ABSTRACT

COVID-19 caused by the SARS-CoV-2 virus has become a global pandemic. 3CL protease is a virally encoded protein that is essential across a broad spectrum of coronaviruses with no close human analogs. The designed phosphate prodrug PF-07304814 is metabolized to PF-00835321 which is a potent inhibitor in vitro of the coronavirus family 3CL pro, with selectivity over human host protease targets. Furthermore, PF-00835231 exhibits potent in vitro antiviral activity against SARS-CoV-2 as a single agent and it is additive/synergistic in combination with remdesivir. We present the ADME, safety, in vitro , and in vivo antiviral activity data that supports the clinical evaluation of this compound as a potential COVID-19 treatment.

6.
Preprint in English | bioRxiv | ID: ppbiorxiv-293498

ABSTRACT

COVID-19 caused by the SARS-CoV-2 virus has become a global pandemic. 3CL protease is a virally encoded protein that is essential across a broad spectrum of coronaviruses with no close human analogs. The designed phosphate prodrug PF-07304814 is metabolized to PF-00835321 which is a potent inhibitor in vitro of the coronavirus family 3CL pro, with selectivity over human host protease targets. Furthermore, PF-00835231 exhibits potent in vitro antiviral activity against SARS-CoV-2 as a single agent and it is additive/synergistic in combination with remdesivir. We present the ADME, safety, in vitro, and in vivo antiviral activity data that supports the clinical evaluation of this compound as a potential COVID-19 treatment.

8.
BJA Educ ; 20(3): 103-110, 2020 Mar.
Article in English | MEDLINE | ID: mdl-33456937
9.
J Photochem Photobiol B ; 162: 125-145, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27371912

ABSTRACT

Novel series of different hydroxyflavone derivatives and their copper complexes were synthesized. They were characterized using analytical and spectral techniques. The superoxide dismutase (SOD) mimetic activity of the synthesized complexes demonstrated that copper complex of L(10) has promising SOD-mimetic activity than other ligands & complexes. The in vitro antimicrobial activities of the synthesized compounds were tested against the bacterial species and fungal species. The DNA binding properties of copper complexes were studied using cyclic voltametry and electronic absorption techniques. Anti-tuberculosis activity was also performed. The effective complexes was subjected to antimycobacterial activity using MABA method and summarized. The antimycobacterial activity of copper complexes have been evaluated and discussed.


Subject(s)
Antitubercular Agents/chemical synthesis , Antitubercular Agents/pharmacology , Copper/chemistry , Flavones/chemistry , Antitubercular Agents/chemistry , Microbial Sensitivity Tests , Microscopy, Electron, Scanning , Mycobacterium tuberculosis/drug effects , Spectrum Analysis/methods , Thermogravimetry
10.
Qual Life Res ; 25(4): 767-79, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26346986

ABSTRACT

BACKGROUND: Systematic reviews of outcome measurement instruments are important tools for the selection of instruments for research and clinical practice. Our aim was to assess the quality of systematic reviews of health-related outcome measurement instruments and to determine whether the quality has improved since our previous study in 2007. METHODS: A systematic literature search was performed in MEDLINE and EMBASE between July 1, 2013, and June 19, 2014. The quality of the reviews was rated using a study-specific checklist. RESULTS: A total of 102 reviews were included. In many reviews the search strategy was considered not comprehensive; in only 59 % of the reviews a search was performed in EMBASE and in about half of the reviews there was doubt about the comprehensiveness of the search terms used for type of measurement instruments and measurement properties. In 41 % of the reviews, compared to 30 % in our previous study, the methodological quality of the included studies was assessed. In 58 %, compared to 55 %, the quality of the included instruments was assessed. In 42 %, compared to 7 %, a data synthesis was performed in which the results from multiple studies on the same instrument were somehow combined. CONCLUSION: Despite a clear improvement in the quality of systematic reviews of outcome measurement instruments in comparison with our previous study in 2007, there is still room for improvement with regard to the search strategy, and especially the quality assessment of the included studies and the included instruments, and the data synthesis.


Subject(s)
Outcome Assessment, Health Care , Patient Outcome Assessment , Research/standards , Review Literature as Topic , Checklist , Humans , Quality of Life
11.
J Pharm Sci ; 101(9): 3110-23, 2012 Sep.
Article in English | MEDLINE | ID: mdl-22461087

ABSTRACT

The objective of the present work was to determine whether hydrolysis in a model lyophile was influenced by general media effects with water-changing properties of the medium or via a specific mechanism of water as a reactant. Four formulations of zoniporide and sucrose (1:10) were prepared with variable amounts of sorbitol [0%-25% (w/v) of total solids). These formulations were then equilibrated at 6% and 11% relative humidity using saturated salt solutions. The lyophile cakes were analyzed by differential scanning calorimetery (DSC), (isothermal microcalorimetry (IMC), solid- state nuclear magnetic resonance (ssNMR) spectroscopy, and ultraviolet-visible diffuse reflectance (DFR) spectroscopy. DSC and IMC were used to assess the global molecular mobility. ssNMR relaxation times were measured to access local mobility. The DFR was used to determine the solid-state acidity expressed as the Hammett acidity function. Stability of samples was evaluated at 40°C by monitoring potency and purity by high-performance liquid chromatography (HPLC). Results were interpreted in terms of the various roles of water: media effect, plasticization, polarity, and reactant. The kinetics of hydrolysis was observed to be correlated with either/both specific "chemical" effects, that is, water reactant as well as media effect, specifically global molecular mobility of the matrix. Increase in reaction rate with increase in water content is not linear and is a weaker dependence than in some hydrolytic reactions in organic solvents. A moderate amount of an inert plasticizer, sorbitol, conferred additional stabilization, possibly by restricting the amplitude and frequency of fast motions that are on a small length scale.


Subject(s)
Freeze Drying , Guanidines/chemistry , Pyrazoles/chemistry , Solvents/chemistry , Technology, Pharmaceutical/methods , Water/chemistry , Calorimetry, Differential Scanning , Chemistry, Pharmaceutical , Chromatography, High Pressure Liquid , Diffusion , Drug Stability , Excipients/chemistry , Hydrolysis , Kinetics , Magnetic Resonance Spectroscopy , Models, Chemical , Plasticizers/chemistry , Sorbitol/chemistry , Spectrophotometry, Ultraviolet , Sucrose/chemistry , Temperature
12.
J Pharm Sci ; 101(1): 283-90, 2012 Jan.
Article in English | MEDLINE | ID: mdl-21935954

ABSTRACT

In this study, changes in the local conformation of aspartame were observed in annealed lyophilized glasses by monitoring changes in the distance between two labeled sites using C-(2)H rotational-echo double-resonance (REDOR) nuclear magnetic resonance (NMR) spectroscopy. Confirmation that the REDOR experiments were producing accurate distance measurement was ensured by measuring the (13)C-(15)N distance in glycine. The experiment was further verified by measuring the REDOR dephasing curve on (13)C-(2)H methionine. (13)C-(2)H REDOR dephasing curves were then measured on lyophilized aspartame-disaccharide formulations. In aspartame-sucrose formulation, the internuclear distances increased upon annealing, which correlated with decreased chemical reactivity. By contrast, annealing had only a minimal effect on the dephasing curve in aspartame-trehalose formulation. The results show that stability is a function of both mobility and local structure (conformation), even in a small molecule system such as lyophilized aspartame-sucrose.


Subject(s)
Aspartame/chemistry , Carbon/chemistry , Deuterium/chemistry , Magnetic Resonance Spectroscopy/methods , Chemistry, Pharmaceutical/methods , Drug Stability , Freeze Drying/methods , Glycine/chemistry , Methionine/chemistry , Molecular Conformation , Trehalose/chemistry
13.
Aliment Pharmacol Ther ; 34(2): 205-13, 2011 Jul.
Article in English | MEDLINE | ID: mdl-21605146

ABSTRACT

BACKGROUND: Standard of practice involves using transarterial therapy for multifocal hepatocellular carcinoma (HCC) alone and sorafenib only for more advanced HCC, but the sorafenib and transarterial therapy combination may provide greater efficacy. AIM: To evaluate the safety and efficacy of concurrent sorafenib and transarterial therapy in HCC. METHODS: Consecutive cases of HCC were treated with sorafenib and transarterial therapy, receiving sorafenib 2 to 4weeks before transarterial therapy. Baseline clinical parameters, adverse events (AEs) and survival were collected. RESULTS: A total of 47 patients received sorafenib and transarterial therapy. The majority of the patients were male (70%) with HCV (60%), median age of 60years, good performance status (0-1), stable cirrhosis (Child: A 72%; B 28%), unresectable tumour (stage: B 81%; C 19%) and median AFP of 24ng/mL. Median follow-up was 12months and median time on sorafenib was 6months. LC Bead TACE was used with a median frequency of 3. The majority of the patients (89%) experienced AEs. The most common AEs were fatigue (51%), hand-foot skin reaction (51%) and diarrhoea (43%). Grade 3 and 4 AEs included fatigue (13%) and hand-foot skin reaction (26%). Most patients required a dose reduction (66%). The main AE related to transarterial therapy was post-TACE syndrome (23%). The disease control rate was 68% at 6months. Overall median survival rate was 18.5months (95% CI 16.1-20.9months). CONCLUSION: Concurrent sorafenib and transarterial therapy is overall safe with no unexpected side effects and encouraging efficacy that warrants further study.


Subject(s)
Antineoplastic Agents/therapeutic use , Benzenesulfonates/therapeutic use , Carcinoma, Hepatocellular/therapy , Chemoembolization, Therapeutic , Liver Neoplasms/therapy , Pyridines/therapeutic use , Aged , Antineoplastic Agents/adverse effects , Benzenesulfonates/adverse effects , Carcinoma, Hepatocellular/drug therapy , Combined Modality Therapy , Female , Humans , Liver Neoplasms/drug therapy , Male , Middle Aged , Niacinamide/analogs & derivatives , Phenylurea Compounds , Pyridines/adverse effects , Sorafenib , Treatment Outcome
14.
AAPS PharmSciTech ; 12(1): 379-87, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21359604

ABSTRACT

The secondary drying phase in freeze drying is mostly developed on a trial-and-error basis due to the lack of appropriate noninvasive process analyzers. This study describes for the first time the application of Tunable Diode Laser Absorption Spectroscopy, a spectroscopic and noninvasive sensor for monitoring secondary drying in laboratory-scale freeze drying with the overall purpose of targeting intermediate moisture contents in the product. Bovine serum albumin/sucrose mixtures were used as a model system to imitate high concentrated antibody formulations. First, the rate of water desorption during secondary drying at constant product temperatures (-22 °C, -10 °C, and 0 °C) was investigated for three different shelf temperatures. Residual moisture contents of sampled vials were determined by Karl Fischer titration. An equilibration step was implemented to ensure homogeneous distribution of moisture (within 1%) in all vials. The residual moisture revealed a linear relationship to the water desorption rate for different temperatures, allowing the evaluation of an anchor point from noninvasive flow rate measurements without removal of samples from the freeze dryer. The accuracy of mass flow integration from this anchor point was found to be about 0.5%. In a second step, the concept was successfully tested in a confirmation experiment. Here, good agreement was found for the initial moisture content (anchor point) and the subsequent monitoring and targeting of intermediate moisture contents. The present approach for monitoring secondary drying indicated great potential to find wider application in sterile operations on production scale in pharmaceutical freeze drying.


Subject(s)
Freeze Drying , Pharmaceutical Preparations , Spectrum Analysis , Absorption , Animals , Cattle , Desiccation , Freeze Drying/instrumentation , Freeze Drying/methods , Serum Albumin, Bovine , Spectrum Analysis/instrumentation , Spectrum Analysis/methods , Sucrose/chemistry , Technology, Pharmaceutical , Temperature , Water/analysis
15.
Funct Integr Genomics ; 10(2): 207-14, 2010 May.
Article in English | MEDLINE | ID: mdl-19809842

ABSTRACT

Sugarcane is an important international commodity as a valuable agricultural crop especially in developing countries. Sequencing was carried out to generate >35,000 expressed sequence tags (ESTs) from healthy as well as red-rot-infected tissue of Indian subtropical variety of sugarcane. Subsequent clustering with existing sugarcane ESTs in public databases identified 4,087 clusters, including 85 clusters that preferentially express upon Colletotrichum falcatum (red-rot) infection, which were previously unreported. Real-time reverse transcription-PCR profiling of selected EST clusters identified several sugarcane clusters that show differential expression in response to biotic and abiotic stress conditions. Twenty-five stress-related clusters showed >2-fold relative expression during water-deficit stress in sugarcane. Similarly, EST clusters could be identified, which exhibit association with red-rot disease when assessed in red-rot-susceptible and red-rot-resistant varieties of sugarcane. Such EST clusters are good candidates for in-depth analysis to elucidate stress-responsive pathways in sugarcane and facilitate genetic manipulation to tailor this crop for tolerance to various stresses.


Subject(s)
Colletotrichum/physiology , Genes, Plant/genetics , Plant Diseases/genetics , Plant Diseases/microbiology , Saccharum/genetics , Stress, Physiological/genetics , Water/metabolism , Base Sequence , Cluster Analysis , Expressed Sequence Tags , Gene Expression Regulation, Plant , Kinetics , Reverse Transcriptase Polymerase Chain Reaction , Sequence Analysis, DNA
16.
Clin Exp Rheumatol ; 27(1): 7-14, 2009.
Article in English | MEDLINE | ID: mdl-19327223

ABSTRACT

OBJECTIVE: The aim of the present study was to investigate the long-term efficacy of a 3-week intensive residential multidisciplinary non-pharmacological treatment program (including individually prescribed and monitored aerobic exercise and cognitive behavioural therapy) on fibromyalgia symptoms and aerobic fitness. METHODS: Twenty-five women with fibromyalgia participated in six experimental sessions (pre-admission, immediately before and immediately after the treatment, and to 2, 5 and 12 months afterwards) in which they underwent clinical, psychophysical and psychological examinations: pain intensity (VAS), pain area (percentage of total body surface), deep pressure pain threshold at 18 tender point sites measured with a pressure algometer, an incremental step test with blood lactate determination and calculation of the individual intensity of exercise corresponding to 2 mM of lactate concentration (W2, index of aerobic fitness). Depression and coping were evaluated with the Center for Epidemiologic Studies Depression Scale (CES-D) and Brief Pain Coping Inventory (BPCI), respectively. RESULTS: Pain intensity, pain area and number of positive tender points were significantly reduced up to 12 months, while deep pressure pain threshold and W2 increased. CES-D score decreased until two months. Among the 18 items of the BCPI, only item 3 ("physical exercise/stretching") changed significantly, increasing until 12 months. CONCLUSION: In fibromyalgia patients, whose symptoms before treatment were constant, a 3-week intensive residential multidisciplinary treatment program showed one-year efficacy in improving pain and aerobic fitness. The acquisition of physical exercise as a coping strategy for chronic pain acceptance could explain the long-term effects of our brief treatment.


Subject(s)
Cognitive Behavioral Therapy , Exercise Therapy/methods , Fibromyalgia/therapy , Relaxation Therapy , Adaptation, Psychological , Adult , Combined Modality Therapy , Depression/complications , Depression/therapy , Exercise , Female , Fibromyalgia/psychology , Follow-Up Studies , Humans , Middle Aged , Pain/psychology , Pain Management , Pain Measurement , Severity of Illness Index
17.
Arch Ital Biol ; 146(2): 75-82, 2008 Jun.
Article in English | MEDLINE | ID: mdl-18822796

ABSTRACT

The study investigated the differences in pain perception in highly (Highs) and low (Lows) hypnotizable patients with chronic benign pain undergoing hypnotic suggestions of analgesia. Self reports of pain intensity were collected in different groups of fibromyalgic patients: (1) Highs and Lows during pre-hypnosis, neutral hypnosis, suggestions for analgesia, posthypnotic conditions; (2) Lows during suggestions for analgesia administered after a mental stress instead of neutral hypnosis; (3) healthy Lows receiving nociceptive stimulation during hypnotic relaxation and suggestions of analgesia. The results showed that Highs and Lows differed in their response to suggestions, but significant analgesia was reported also by Lows. These individuals did not report any difference in pain perception between the sessions including mental stress and hypnotic relaxation. No change in pain perception was observed in healthy Lows during nociceptive stimulation associated with relaxation and suggestions for analgesia. In conclusion, the presence of chronic pain seems to be responsible for the paradoxical response of non hypnotizable patients to hypnotic suggestions.


Subject(s)
Analgesia/methods , Analgesia/psychology , Fibromyalgia/psychology , Fibromyalgia/therapy , Hypnosis/methods , Adult , Chronic Disease , Female , Humans , Middle Aged , Nociceptors/physiology , Pain Measurement/psychology , Pain Threshold/psychology , Physical Stimulation , Stress, Psychological/complications , Stress, Psychological/psychology , Stress, Psychological/therapy , Suggestion , Treatment Outcome
18.
J Pharm Sci ; 97(12): 5240-51, 2008 Dec.
Article in English | MEDLINE | ID: mdl-18481306

ABSTRACT

This research constitutes a thorough study of the relationship between the chemical stability, aging state and global molecular motion on the one hand, and microscopic local mobility in multi-component systems on the other hand. The objective of the present work was to determine whether annealing a glass below T(g) affects its chemical stability and determine if the rate of chemical degradation couples with global relaxation times determined using calorimetery, and/or with T(1) and T(1rho) relaxation times measured using ssNMR. Model compounds chosen for this research were lyophilized aspartame/sucrose and aspartame/trehalose (1:10 w/w) formulations. The chemical degradation was assessed at various temperatures using high-performance liquid chromatography (HPLC) to determine the impact of annealing on chemical stability. The rate constant for chemical degradation was estimated using stretched time kinetics. The results support the hypothesis that thermal history affects the molecular mobility required for structural relaxation and such effect is critical for chemical stability, that is, a stabilization effect upon annealing is observed.


Subject(s)
Freeze Drying , Glass , Pharmaceutical Preparations , Chromatography, High Pressure Liquid , Kinetics , Magnetic Resonance Spectroscopy
19.
J Pharm Sci ; 97(10): 4336-46, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18240306

ABSTRACT

The purpose of this study was to investigate the impact of annealing on molecular mobility in lyophilized glasses, composed of a saccharide excipient and a small concentration of aspartame as a model "drug." Changes in molecular dynamics during annealing were monitored through carbon ((13)C) T(1) and T(1 rho) nuclear magnetic resonance relaxation times of the aspartame and the saccharides. Two different saccharides were studied, sucrose and trehalose. The local mobility of the aspartame guest was found to correlate closely with the overall structural relaxation monitored through calorimetric methods in the aspartame: sucrose formulation. In general terms, annealing leads to longer NMR relaxation times, indicating a slowing of the local dynamics. By contrast, annealing had only a minimal effect on the NMR relaxation times in aspartame: trehalose. Specificity of solid state NMR in detecting molecular mobility in guest and host molecules showed that sucrose provided a homogenous matrix for the guest drug as compared to the trehalose.


Subject(s)
Freeze Drying , Glass , Hot Temperature , Magnetic Resonance Spectroscopy/methods , Aspartame/chemistry , Trehalose/chemistry
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