Rheological behavior study and its significance in the assessment of application properties and physical stability of phytosome loaded hydrogels

Phytosomes are amphiphilic molecular complexes of substances of plant origin and phospholipids that are considered as active ingredients of dermopharmaceutical and cosmetic formulations of potentially improved efficiency. The study aim was the formulation of carbomer hydrogels with commercially available phytosomes of escin (Escin ß-Sitosterol Phytosome®) (EP) and 18-ß glycyrrhetinic acid (18-ß Glycyrrhetinic Acid Phytosome®) (GP) and evaluation of their application properties and real-time physical stability. Phytosomes incorporation did not significantly affect pH of the hydrogels, which was acceptable for cutaneous application. However, these hydrogels had significantly different organoleptic properties (opaque and softer consistency) compared to the hydrogel without active substance (C) and the hydrogels with pure active substances (E and G) used for comparison. The values of maximum and minimum apparent viscosity and yield stress were significantly lower in phytosome-loaded hydrogels. The results of oscillatory rheological analysis indicated that viscous character prevails in EP and GP hydrogels (elastic modulus (G')˂viscous modulus (G")), while in hydrogels C, E and G elastic properties were more pronounced (G'˃G"). Escin phytosome had greater influence on carbomer gel network strength. Phytosome-loaded hydrogels were physically stable during 24 months of storage under ambient conditions, although the rheological analysis also indicated a potential risk of sedimentation.

Download Full-text

Influence of β-Cyclodextrin and Hydroxypropyl-β-Cyclodextrin on Enhancement of Solubility and Dissolution of Isradipine

International Journal of Pharmaceutical Sciences and Nanotechnology ◽

10.37285/ijpsn.2017.10.3.8 ◽

2017 ◽

Vol 10 (3) ◽

pp. 3752-3757

Author(s):

Narendar D ◽

Ettireddy S

Keyword(s):

Inclusion Complex ◽

Dissolution Rate ◽

Solid Dispersions ◽

Physical Stability ◽

Molecular Complexes ◽

In Vitro Dissolution ◽

Molar Ratio ◽

Phase Solubility ◽

Cyclodextrin Complexation

The content of this investigation was to study the influence of β-cyclodextrin and hydroxy propyl-β-cyclodextrin complexation on enhancement of solubility and dissolution rate of isradipine. Based on preliminary phase solubility studies, solid complexes prepared by freeze drying method in 1:1 molar ratio were selected and characterized by DSC for confirmation of complex formation. Prepared solid dispersions were evaluated for drug content, solubility and in vitro dissolution. The physical stability of optimized formulation was studied at refrigerated and room temperature for 2 months. Solid state characterization of optimized complex performed by DSC and XRD studies. Dissolution rate of isradipine was increased compared with pure drug and more with HP-β-CD inclusion complex than β-CD. DSC and XRD analyzes that drug was in amorphous form, when the drug was incorporated as isradipine β-CD and HP-β-CD inclusion complex. Stability studies resulted in low or no variations in the percentage of complexation efficiency suggesting good stability of molecular complexes. The results conclusively demonstrated that the enhancement of solubility and dissolution rate of isradipine by drug-cyclodextrin complexation was achieved.

Download Full-text

Storage of ‘umbu-cajá’ pulp powder produced by lyophilization

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v20n12p1118-1123 ◽

2016 ◽

Vol 20 (12) ◽

pp. 1118-1123 ◽

Cited By ~ 1

Author(s):

Dyego da C. Santos ◽

Ana P. T. Rocha ◽

Josivanda P. Gomes ◽

Emanuel N. A. de Oliveira ◽

Esther M. B. de Albuquerque ◽

...

Keyword(s):

Ascorbic Acid ◽

Reducing Sugars ◽

Physical Stability ◽

Gum Arabic ◽

Titratable Acidity ◽

Ambient Conditions ◽

Physical Chemical ◽

Physico Chemical

ABSTRACT This work aimed to study the chemical and physical stability of ‘umbu-cajá’ powders produced by lyophilization during storage. ‘Umbu-cajá’ pulps formulated with different concentrations of gum arabic (10, 20 and 30%), previously frozen, were dehydrated in benchtop lyophilizer at -40 °C for 48 h and disintegrated to obtain the powder, which was stored in laminated packages for 180 days at ambient conditions, with physical, chemical and physico-chemical analyzes performed at the beginning and every 30 days of storage. According to the results, all investigated parameters were significantly altered throughout the storage, yet with less intense variations for important variables, such as ascorbic acid, reducing sugars and titratable acidity. At the end of storage, all powders were microbiologically safe.

Download Full-text

Comprehensive insights into synthetic nitrogen fixation assisted by molecular catalysts under ambient or mild conditions

Chemical Society Reviews ◽

10.1039/d0cs01341b ◽

2021 ◽

Author(s):

Yoshiaki Tanabe ◽

Yoshiaki Nishibayashi

Keyword(s):

Nitrogen Fixation ◽

Transition Metal ◽

Biological Nitrogen Fixation ◽

Molecular Complexes ◽

Alternative Methods ◽

Ambient Conditions ◽

Mild Conditions ◽

Molecular Catalysts ◽

Biological Nitrogen ◽

Harsh Conditions

N2 is fixed as NH3 industrially by the Haber–Bosch process under harsh conditions, whereas biological nitrogen fixation is achieved under ambient conditions, which has prompted development of alternative methods to fix N2 catalyzed by transition metal molecular complexes.

Download Full-text

Pharmaceutical Cocrystals: An Emerging Approach to Physical Property Enhancement

MRS Bulletin ◽

10.1557/mrs2006.206 ◽

2006 ◽

Vol 31 (11) ◽

pp. 875-879 ◽

Cited By ~ 216

Author(s):

William Jones ◽

W.D. Samuel Motherwell ◽

Andrew V. Trask

Keyword(s):

Physical Properties ◽

Physical Stability ◽

Physical Property ◽

Molecular Complexes ◽

Growth Potential ◽

Pharmaceutical Cocrystals ◽

Design And Synthesis ◽

Therapeutic Molecules ◽

Salt Selection ◽

Synthetic Approaches

AbstractPharmaceutical cocrystals are crystalline molecular complexes containing therapeutic molecules. They represent an emerging class of pharmaceutical materials offering the prospect of optimized physical properties. This article highlights important opportunities and challenges associated with the design and synthesis of pharmaceutical cocrystals. Cocrystallization is first placed into context with the more established approaches to physical property optimization of polymorph, hydrate, and salt selection. A directed, intermolecular-interaction-based approach to cocrystal design is described. The enhancement of specific physical properties, such as dissolution rate and physical stability, is illustrated by summarizing several recent reports. Synthetic approaches to cocrystallization are considered; in particular, the selectivity and screening-related opportunities afforded by solid-state grinding and solvent-drop grinding methods are discussed. Finally, an outlook on future developments summarizes the growth potential in this field, especially with regard to targeted, informatics-driven cocrystal screening approaches.

Download Full-text

Freeze-etch TEM of aqueous polymer gel network morphology

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100145327 ◽

1986 ◽

Vol 44 ◽

pp. 796-797

Author(s):

J. A. N. Zasadzinski ◽

R. K. Prud'homme

Keyword(s):

Metal Ion ◽

Polymer Network ◽

Polymer Gels ◽

Polymer Gel ◽

Deformation History ◽

Crosslinked Polymer ◽

Aqueous Polymer ◽

History Of ◽

Gel Network ◽

Network Morphology

The rheological and mechanical properties of crosslinked polymer gels arise from the structure of the gel network. In turn, the structure of the gel network results from: thermodynamically determined interactions between the polymer chain segments, the interactions of the crosslinking metal ion with the polymer, and the deformation history of the network. Interpretations of mechanical and rheological measurements on polymer gels invariably begin with a conceptual model of,the microstructure of the gel network derived from polymer kinetic theory. In the present work, we use freeze-etch replication TEM to image the polymer network morphology of titanium crosslinked hydroxypropyl guars in an attempt to directly relate macroscopic phenomena with network structure.

Download Full-text