2‐Hydroxyethyl Methacrylate Hydrogels for Local Drug Delivery: Study of Topotecan and Vincristine Sorption/Desorption Kinetics and Polymer‐Drug Interaction by ATR‐FTIR Spectroscopy

Abstract

Poly(2‐hydroxyethyl methacrylate) (pHEMA) hydrogels are well known in ophthalmological applications and recently investigated as drug delivery systems. The study represents a theoretical approach where the sorption/desorption experiments and spectroscopic study is used to describe the influence of the pHEMA network structure on the sorption capacity and mechanism of the release of topotecan (TPT) and vincristine (VCR). The hydrogels are synthesized by free‐radical crosslinking polymerization of HEMA monomer with ethylene glycol dimethacrylate as a crosslinker in the concentration range from 0.3 to 1 wt%. Experimental data from sorption kinetics are evaluated using sorption kinetic models and sorption isotherms, drug release mechanism is assessed by two different models and attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy is employed to describe the polymer‐drug interaction. pHEMA hydrogels exhibit higher affinity for TPT than for VCR and hydrogels prepared with 0.5 wt% of crosslinker show the maximum sorption capacity for both drugs. Physisorption is proved to be the sorption mechanism. Analyzing the FTIR spectra, it is concluded that the hydrophobic crosslinks play an important role in the interaction of the hydrogel backbone with molecules of both drugs.

Electrostatic Induced Peptide Hydrogels for pH‐Controllable Doxorubicin Release and Antitumor Activity

“…Drug models have been developed to help understand the mechanisms of drug release as well as to predict the temporal distribution of drug concentrations at the site of action in humans and the pharmacodynamic effects on patients under disease conditions [38] . The main mechanisms of drug release from hydrogels are diffusion, desorption and chemical reactions [39–41] . The negatively charged peptide fibers rely on electrostatic interaction to bind to the positively charged drug to form a hydrogel, and a change in pH of the surrounding environment causes the electrostatic interaction to be disrupted, the drug carrier skeleton to dissolve, and the drug to be released.…”

“…[38] The main mechanisms of drug release from hydrogels are diffusion, desorption and chemical reactions. [39][40][41] The negatively charged peptide fibers rely on electrostatic interaction to bind to the positively charged drug to form a hydrogel, and a change in pH of the surrounding environment causes the electrostatic interaction to be disrupted, the drug carrier skeleton to dissolve, and the drug to be released. Such a release behavior may be consistent with the diffusion mechanism of the drug, and to further reveal this drug release mechanism, a program called drug dissolution solver was used to perform model simulations of drug release kinetics.…”

The Role of Cryotherapy in Vitreous Concentrations of Topotecan Delivered by Episcleral Hydrogel Implant

“…The highly vascularized tissue surrounding the eyeball represents a dynamic barrier that eliminates the drug applied by periocular injection [ 44 , 45 , 46 ] or released from the administered device [ 47 , 48 ]. The activity of this barrier can be suppressed by using drug-loaded device which is tightly attached to the eyeball and releases the drug entirely towards the side of the sclera [ 21 , 39 ]. The third barrier is the choroidal blood vasculature.…”

“…Our implant is composed of two methacrylate-based layers: an inner hydrophilic drug reservoir made from poly(2-hydroxyethyl methacrylate) (pHEMA), which delivers low molecular weight hydrophilic drugs such as TPT, and an outer hydrophobic layer of poly(2-ethoxyethyl methacrylate) (pEOEMA), which is impermeable and thus suppresses the release of the drug into the surrounding vascularized tissue; the drug is almost exclusively released towards the sclera. In vitro properties and in vivo proof of concept in a rabbit eye model have been reported [ 38 , 39 , 40 ].…”

Compliant, Tough, Anti-Fatigue, Self-Recovery, and Biocompatible PHEMA-Based Hydrogels for Breast Tissue Replacement Enabled by Hydrogen Bonding Enhancement and Suppressed Phase Separation

“…Although the silicone prosthesis is less likely to leak and contaminate, silicone can lead to regional lymphadenopathy (lymphadenitis is a nonspecific lymphadenitis caused by pathogenic bacteria invading lymphatic vessels from damaged and ruptured skin or mucosa through the lymphatic space of tissues and subsequently involving lymph nodes) and extramammary organ involvement if it leaks [ 12 ]. Therefore, it is necessary to develop a biocompatible prosthesis material that does not cause adverse reactions [ 13 , 14 , 15 , 16 , 17 ]. Hydrogels have a similar water content, porous structure, and good biocompatibility to biological tissue [ 18 , 19 , 20 , 21 , 22 ].…”