Factors influencing the erosion rate and the drug release kinetics from organogels designed as matrices for oral controlled release of a hydrophobic drug

Abstract

This article proposes solid-like systems from sunflower oil structured with a fibrillar network built by the assembly of 12-hydroxystearic acid (12-HSA), a gelator molecule for an oil phase. The resulting organogels were studied as oral controlled release formulations for a lipophilic drug, Efavirenz (EFV), dissolved in the oil. The effects of the gelator concentration on the thermal properties of the organogels were studied by Differential Scanning Calorimetry (DSC) and showed that drug incorporation did not change the sol-gel-sol transitions. The erosion and drug release kinetics from organogels under conventional (filling gelatin capsules) or multiparticulate (beads obtained by prilling) dosage forms were measured in simulated gastric and intestinal fluids. EFV release profiles were analyzed using model-dependent (curve-fitting) and independent approaches (Dissolution Efficiency DE). Korsmeyer-Peppas was the best fitting release kinetic model based on the goodness of fit, revealing a release mechanism from organogels loaded with EFV different from the simple drug diffusion release mechanism obtained from oily formulations. From organogels, EFV probably diffuses through an outer gel layer that erodes releasing oil droplets containing dissolved EFV into the aqueous medium.

Reversibly Softening and Stiffening Organogels Using a Wavelength-Controlled Disulfide-Diselenide Exchange

“…Photoresponsive organogels are a set of materials with potential applications in sensors, , drug delivery, , controlled release, , and artificial muscles . Polymers and small molecules have both been used as gelling agents in organogels .…”

“…Typically, low molecular weight organogelators form networks through physical interactions, while polymeric organogelators form networks through chain entanglements or a combination of chemical and physical cross-linking . Organogels can be responsive to a number of external stimuli depending on the cross-linking chemistry, including light, , temperature, ,, redox agents, ,, and ultrasound . Light is a useful external trigger to induce responses in stimuli-responsive materials, as it can be applied locally without suffering from diffusion effects and be switched “on” and “off” easily .…”

Structuring Edible Oils With Fumed Silica Particles

“…They proposed that release was controlled by diffusion of the drug molecules through the gel during this stage. The second stage was characterized by a faster release rate (Lupi et al, 2013(Lupi et al, , 2018Pereira Camelo et al, 2016). The rate exceeded predictions by models for the release of drugs from polymer matrices due to diffusion alone (Siepmann and Siepmann, 2008;Fredenberg et al, 2011).…”

How an organogelator can gelate water: gelation transfer from oil to water induced by a nanoemulsion

“…36 As organogelator we selected 12-hydroxyoctadecanoic acid (12-HOA), also biocompatible and used in pharmaceutical applications. 37 Another point of interest of 12-HOA lies in its gelling power, allowing the gelation of many oils and organics solvents, even at very low concentrations. [10][11][12][13][14][15] As expected, 12-HOA was able to gellify the Miglyol s 812 between 1-25 wt% (as illustrated by the inverted bottle test in Fig.…”

“…PIT emulsification is based on the changes in the solubility (curvature) of surfactants depending on the temperature. [33][34][35][36][37] For example, nonionic surfactants of the polyoxyethylene kinds are hydrophilic and soluble in water at low temperatures. 30 When the temperature is raised, they turn lipophilic and become more soluble in the oil phase.…”