Stimuli-responsive hydrogels for controlled pilocarpine ocular delivery

Multiple Stimuli-Responsive Hydrogels for Metal-Based Drug Therapy

“…It is obvious that, in the range of the temperature considered, the ionic/ionizable groups superimposed their electrostatic repulsion along with the hydrophilic quality due to the great degree of solvation. The hydration state of the homopolymeric AVa hydrogels show to behave quite unusual for the effect of temperature and at different pHs [26,39]. In all cases, the increase of temperature led to a decrease of EDS.…”

“…The swelling properties of the hydrogels carrying the L-valine residues (AVa) show a sharp decrease of the equilibrium degree of swelling (EDS) in correspondence of a pH value close to the critical degree of protonation of the carboxylate anion [26,35,36,39]. This degree of protonation, corresponding to 0.66, was related to the collapse of the macromolecular coil that forces the isopropyl groups in a close contact, outweighing the repulsive electrostatic interactions of the partially ionized polymer in a more extended and hydrated conformation.…”

“…The swelling of the hydrogels was monitored at different pHs, temperatures, and ionic strengths, as outlined in a previously reported procedure [27,29,39]. A weighed sample of dry gel (10-30 mg) in a Strained cell was suspended in the buffer solution (PBS or acetate) of desired pH contained in a thermostatted glass cell (100 mL), connected to a temperature probe and a glass electrode.…”

A New Preparation Method for Ophthalmic Drug Nanoparticles

“…In this regard, it is very important to increase the effectiveness of drugs by enhancing their bioavailability [6]. In order to overcome these problems and increase ocular drug bioavailability, several strategies including the preparation of viscous solutions, micro/nanoparticles and hydrogels have been developed and investigated [1,4,[7][8][9][10]. In the case of viscous solutions, numerous studies have demonstrated that they do not possess sufficient mechanical strength to resist the ocular clearance mechanism, and offer only a transient improvement in ocular residence time [11,12].…”

Evaluation of pH-sensitive poly(2-hydroxyethyl methacrylate-co-2-(diisopropylamino)ethyl methacrylate) copolymers as drug delivery systems for potential applications in ophthalmic therapies/ocular delivery of drugs

“…Due to its properties, sensitive hydrogels have been proposed for a number of applications like drug delivery, separation techniques and sensors [7][8][9]. Recently sensitive hydrogels have been also proposed for ocular drug delivery systems in order to improve the ocular bioavailability of drugs, and to reduce the appearance of side effects [10]. In this case, within topical application of drugs, the presence of ocular compact barrier in the corneal and conjunctival epithelia of the eye, along with the dynamics of the lacrimal system, hinder the drug absorption into the intraocular area [11,12].…”