Study of factors affecting the in vitro release of diclofenac sodium from hypromelose-based gels

The aim. To identify some factors affecting the in vitro release of ketoprofen from carbomer-based gels. Materials and methods. Carbomer-based gels containing ketoprofen as well as a Newtonian liquid without carbomer, which was the dispersion medium of the gel, were studied by rotational viscometry and spin probe method. The flow behaviour and rheological parameters were determined using the rheograms, and the rotational correlation times of the two dissolved spin probes, the molecules of which contain a carboxyl group or an amino group, were determined by EPR spectra. In vitro release tests were performed using vertical diffusion chambers using a validated method. The quantitative determination of ketoprofen in gels, liquid and receptor medium was performed by liquid chromatography, and ethanol was quantified by gas chromatography according to validated procedures. Gels with different brands of carbomers, neutralised with trolamine or trometamol, with different contents of ketoprofen and ethanol, and with pH from 6.0 to 7.0 were studied. Results. The sol → gel transition due to the neutralisation of the carbomer did not affect the shape and parameters of the EPR spectrum of the spin probe containing a carboxyl group in the molecule (like a carbomer and ketoprofen) in contrast to the probe with an amino group. If the substance dissolved in the gels does not interact with the carbomer, then its molecules/ions rotate rapidly in the liquid medium. This facilitates the release of a such substance from carbomer-based gels. The medicinal product Nobi Gel® gel 2.5 % and Newtonian liquid were equivalent in relation to the in vitro release parameters of ketoprofen from these objects. Сarbomer-based gels, which differed significantly in terms of rheological parameters, were also found to be equivalent in terms of ketoprofen release parameters. The in vitro release of ketoprofen was affected by its concentration and ethanol content in the gel. A change in pH from 6.0 to 7.0 practically did not affect the parameters of in vitro release of ketoprofen from gels. Conclusions. The formation of a carbomer-based gel did not affect the rotational correlation time of the probe, which did not interact with the carbomer. Parameters of in vitro release of ketoprofen from the gel and Newtonian liquid differed little; these parameters were also little affected by the difference in apparent viscosity of the gels. The in vitro release of ketoprofen depended on its concentration and ethanol content

Section: Research By Rotating Viscometer Methods and Spin Probes Methodsmentioning

confidence: 99%

Study of factors affecting the in vitro release of ketoprofen from carbomers-based gels

Bezugla

Liapunova

Zinchenko

et al. 2022

“…The physical stability of microheterogeneous disperse systems depends among other things on the viscosity of the liquid dispersion medium, and the release of dissolved active substances from the base-vehicle may depend on the microviscosity of their local surrounding [28]. Fig.…”

Section: Study Of the Effect Of P338 On The Structure Of Micelles And Aggregates Of Surfactants With Csamentioning

confidence: 99%

Interaction of surfactants with poloxamers 338 and its effect on some properties of cream base

Bezuglaya

Lyapunov

Lysokobylka

et al. 2021

Self Cite

The aim. Study of the interaction of surfactants with poloxamer 338 (P338) and the effect of P338 on the properties of cream bases. Materials and methods. Solutions of the surfactants and P338 as well as cream bases were under study. The average hydrodynamic diameter (Dh) and zeta potential (ζ‑potential) were determined by the light scattering intensity and electrophoretic mobility of micelles. The electron paramagnetic resonance (EPR) spectra of spin probes in micelles, solvents and bases were obtained; the type of spectrum, isotropic constant (AN), rotational correlation times (τ) and anisotropy parameter (ε) were determined. Liquids and cream bases were studied by capillary and rotational viscometry; the flow behaviour and yield stress (t0), dynamic and apparent viscosity (η) as well as the hysteresis (thixotropic) area (AH) were determined. The microstructure of the bases was examined by optical microscopy. The strength of adhesion (Sm) was assessed by the pull-off test, and the absorption of water was studied by dialysis. Results. Under the impact of P338 the hydrodynamic diameters of micelles formed by cationic, anionic and nonionic surfactants decreased as well as the absolute values of their ζ‑potential became lower, but the microviscosity of the micelle nuclei increased. There was also a change in the structure of the aggregates of surfactant with fatty alcohols; EPR spectra, which were superpositions characteristic for the lateral phase separation, converted into triplets that indicated the uniform distribution of lipophilic probes in the surfactant phase. When the content of P338 increased to 17 %, the rheological parameters of the bases increased drastically, the flow behaviour and the microstructure changed. The bases had the consistency of cream within temperature range from 25 °C to 70 °C and completely restored their apparent viscosity, which had decreased under shear stress. P338 enhances the adhesive properties of the bases. Due to their microstructure, cream bases have a lower ability to absorb water compared to a solution and gel containing 17 % and 20 % P338, respectively. Conclusions. The structure of surfactant micelles and aggregates of surfactants with fatty alcohols changed under impact of P338 due to the interaction of surfactants with P338. As a result of this interaction, at a sufficiently high concentration of P338, the microstructure and flow behaviour of bases changed, their rheological parameters, which remain high at temperatures from 25 °C to 70 °C, increased significantly, and water absorption parameters decreased. The bases with P338 were more adhesive

“…The most commonly used hydrophilic solvents in pharmacy are ethanol, glycerin, isopropyl alcohol, liquid macrogols (macrogols 200, 300, and 400), propylene glycol (PG), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (N-MP), diethylene glycol monoethyl ether (DME), etc. The functional purpose of these solvents may be related to their use as co-solvents of active substances and other excipients [2], penetration enhancers [3], moisturisers [1], substances that provide antimicrobial preservative effect [4], osmotically active substances that absorb exudate [5], drug release modifiers [6], etc.…”

Section: Introductionmentioning

confidence: 99%

Influence of physicochemical properties and structure of mixed solvents propylene glycol – macrogol 400 on their in vitro release

Bezuglaya

Krasnopyorova

Liapunova

et al. 2023

Aim. To study the density and dynamic viscosity of the mixed solvents propylene glycol (PG) – macrogol 400 (M400), to calculate their excess values and excess activation parameters of viscous flow, to evaluate the features of the structure of the mixed solvents and its influence on the in vitro release of PG and M400. Materials and methods. The mixed solvents PG - M400 were studied over the entire concentration range at temperatures from 293.15 to 313.15 K. The density and dynamic viscosity were determined, and the excess density, excess dynamic viscosity, activation parameters of viscous flow, and excess activation parameters of viscous flow were calculated. The in vitro release of PG and M400 from the mixed solvents was studied using vertical diffusion cells. The content of PG and M400 in the receptor medium was determined by gas chromatography using validated analytical procedures. The release rate, cumulative content, percentage of released PG or M400, coefficients of correlation and coefficients of determination were calculated. Results. The isotherms of excess density and excess dynamic viscosity of the mixed solvents PG-M400 pass through a maximum. The enthalpy makes the main contribution to the free activation energy of the viscous flow. The excess free energy is positive and has small values; the values of the excess entropy and excess enthalpy are negative, and the isotherms have the minimum at PG concentrations of 70‑75mol %. The release parameters of M400 are greater in binary mixtures where the M400 structure predominates. At PG content of ~75 mol %, the release parameters for PG and M400 are identical. With the increase in PG content above 75 mol %, when the PG structure predominates in the system, the release parameters of PG increase dramatically, and the release parameters of M400 decrease sharply. Conclusions. The structure of the binary system PG – M400 depends on its composition. Based on the isotherms of excess activation of viscous flow, it is possible to differentiate the areas where the structure of PG or the structure of M400 dominates, or the mixed structure of the binary solvent prevails. The in vitro release parameters for PG and M400 depend on the structure of the mixed solvents. The greatest difference in the release parameters of PG and M400 was observed in the area where the structure of PG dominates