In Vitro Dissolution Kinetics of Captopril from Microspheres Manufactured by Solvent Evaporation

Abstract

The aim of this study was to develop and assess captopril-loaded microspheres in which Methocel and Eudragit RS were used as release-controlling factors and to evaluate captopril (CPT) release using kinetic models. Drug-excipient interactions were evaluated using infrared studies, and the physical appearance was characterized using scanning electron microscopy (SEM). A burst effect was observed during the first stage of dissolution for most batches of microspheres. SEM results reveal that this may be attributed to dissolution of captopril crystals that were present on the surface, embedded in the superficial layer of the matrix materials, trapped near the surface of the microspheres, or that may have diffused rapidly through the porous surface of the capsules. The release data generated during in vitro release studies were fitted to zero-order, first-order, Higuchi, Korsmeyer-Peppas, Kopcha, and Makoid-Banakar models. The release kinetics of captopril from most formulations followed a classical Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores located in the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed a predominance of diffusion relative to swelling or erosion throughout the entire test period. The drug release mechanism was also confirmed by the Makoid-Banakar and Korsmeyer-Peppas model exponents. This further supports a diffusion-release mechanism for most formulations. The models postulate that the total drug released is a summation of several mechanisms (viz., burst release, relaxation-induced controlled release, and diffusional release). These results also support the potential application of Eudragit/Methocel microspheres as a suitable sustained-release drug delivery system for captopril.

Preparation of Calcipotriol Emulsion Using Bacterial Exopolysaccharides as Emulsifier for Percutaneous Treatment of Psoriasis Vulgaris

“…Therefore, clinically, there is a certain control on the dosage of CPT drugs, which recommends use only 1-2 times a day, and a maximum dose per week that should not exceed 500 mg. In conclusion, sustained release of CPT appears to be beneficial in the treatment of psoriasis as it leads to its adequate absorption, which helps to reduce drug toxicity [20]. In similar studies, Kaur [4] prepared a clobitasol propionate and CPT nanoemulsion that completely released CPT at 10 h. Also, the cumulative release of CPT from betamethasone dipropionate and CPT loaded solid lipid nanoparticles (CT-BD-SLNs) was only 31.0% at 48 h [21].…”

In vitro silver ion release kinetics from nanosilver/poly(vinyl alcohol) hydrogels synthesized by gamma irradiation

“…The curvilinear nature of the cumulative percentage of released silver versus time plots suggests that silver release from the hydrogel does not follow zero‐order kinetics. The models used to fit obtained Ag + ion release data were as follows: Korsmeyer–Peppas model: This describes the drug release from a polymeric system by a simple relationship, where M t is the amount of drug released at time t; M ∞ is the mass of drug doped into the device at equilibrium; k KP is the Korsmeyer–Peppas constant, which incorporates the characteristics of the macromolecular network or particle system that makes up the formulation; and n is the release exponent that describes the drug‐release (transport) mechanism. Higuchi model, which describes the release of drugs from an insoluble matrix as a square root of a time‐dependent process based on Fickian diffusion: The Hixson–Crowell cube root law, which defines the release from systems by dissolution where there is a change in the SA and the diameter of the particles: where k HC is the Hixson–Crowell constant. The Kopcha model, which describes how to quantify the contributions of diffusion and polymer relaxation: where A and B are the Kopcha constants. Makoid–Banakar's pharmacokinetic dissolution model: where k MB is Makoid–Banakar's constant. …”

Interaction and release kinetics study of hybrid polymer blend nanoparticles for pH independent controlled release of an anti-viral drug

“…The drug release was primarily based on Fickian diffusion transport as suggested by Korsemeyer-Peppas kinetics with n-value <0.5 [32]. The R 2 > 0.98 with least SSR value in Weibull and BakerLonsdale model kinetics suggested the drug release from spherical non-homogenous polymeric matrix system through fractures and capillaries, that was attributed to hydrolysis of PVP from the matrix [33,34].…”