Poly(vinyl alcohol boric acid)-Diclofenac Sodium Salt Drug Delivery Systems: Experimental and Theoretical Studies

Abstract

The main aim of the paper was to simulate the drug release by a multifractal theoretical model, as a valuable method to assess the drug release mechanism. To do this, drug delivery films were prepared by mixing poly(vinyl alcohol boric acid) (PVAB) and diclofenac (DCF) sodium salt drug in different mass ratios from 90/10 to 70/30, in order to obtain drug delivery systems with different releasing rates. The different drug content of the three systems was confirmed by energy-dispersive spectroscopy (EDAX) analysis, and the encapsulation particularities were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and polarized optical microscopy (POM) techniques. The ability of the PVAB matrix to anchor the DCF was assessed by Fourier transform infrared (FTIR) spectroscopy. The in vitro release of the diclofenac sodium salt from the formulations was investigated in biomimetic conditions (pH=7.4 and 37°C) by UV-Vis spectroscopy, measuring the absorbance of the drug at 275 nm and fitting the results on a previously drawn calibration curve. An estimation of the drug release kinetics was performed by fitting three traditional mathematical models on experimental release data. Further, the drug delivery was simulated by the fractal theory of motion, in which the release dynamics of the polymer-drug complex system is described through various Riccati-type “regimes.” To explain such dynamics involved multifractal self-modulation in the form of period doubling, quasiperiodicity, intermittency, etc., as well as multifractal self-modulation of network type. Standard release dynamics were explained by multifractal behaviors of temporary kink type. The good correlation between the traditional mathematical models and the new proposed theoretical model demonstrated the validity of the multifractal model for the investigation of the drug release.

5-Fluorouracil Release from Chitosan-Based Matrix.Experimental and Theoretical Aspects

“…where is the amount of drug dissolved in time and ∞ is the total amount of time dissolved when the pharmaceutical dosage form is exhausted [29,37]. A verification of our model is presented in Figure 5, for the drug release of 5-fluorouracil release from chitosan-based matrix.…”

“…Thus, it is stated that various "mechanisms" involved in the drug release process can be mimed through period doubling, quasi-periodicity, intermittences etc. (for details see [37]). Because through the restriction (15) given, for example, by = − , the multifractal type conservation laws (1) and (2) take the form of the multifractal type "diffusion" equation:…”

“…where 0 is the initial drug states density of the multifractal type in the "device" of multifractal type and 1 is the drug states density at the "polymer-fluid" interface of multifractal type. This solution equation under these conditions can take the following form (for details in the classical case see [37]). In Figure 4 there are represented the An accurate expression can be obtained for small values of since the second term of (20) disappears and then it becomes:…”

A theoretical mathematical model for assessing diclofenac release from chitosan-based formulations

“…Thus, it is stated that various ‘mechanisms’ involved in the drug release process can be mimed through period doubling, quasi – periodicity, intermittences etc. (for details see Ailincai et al., 2020 ).…”

“…Thus, it is stated that various 'mechanisms' involved in the drug release process can be mimed through period doubling, quasiperiodicity, intermittences etc. (for details see Ailincai et al, 2020). Because through the restriction (34) given, for example, by V ¼ ÀU, the multifractal type conservation laws (20) and (21) take the form of the multifractal type 'diffusion' equation:…”