Hydrogel delivery device

A hydrogel delivery device can also be prepared by polymerizing in the presence ofthe protein (Korsmeyer, 1991). The protein must be stable under the polymerization conditions (temperature, solvent, pH) and not react into the hydrogel matrix. The pseudo-steady-state assumptions require that the protein concentration per unit volume exceed the saturation limit (ie., A Cs). Lee (1988) used an integral method for moving-boundary problems to reduce the problem as toJlows ... 

Originality Ongoing investigation on hydrogels as drug delivery devices. 

Sucrose acrylate derivatives can be converted into polymers and hydrogels that can be used as flocculants, water adsorbents, bioimplantables, and drug delivery devices (42). Sucrose ethers have applications as surfactants and surface coatings, and as feedstocks for synthesis of polyurethane foams and... 

Banga, A.K., and Y.W. Chien. 1993. Hydrogel-based iontotherapeutic delivery devices for transdermal delivery of peptides/protein drugs. Pharm Res 10 697. 

Stimuli-responsive homo- and copolymeric hydrogels with pH, temperature, ionic strength, solvation, electrical field, or magnetic field-sensitive pendent groups have been produced for drug, peptide and protein delivery devices, for biosensors and for tissue engineering. Their swelling behaviour, net-... 

The cumulative release profile for diclofenac sodium from the transbuccal delivery device exhibited a square root of time dependency over approximately 80% of the total release process (Figure 3). In view of the drug s solubility within the hydrogel ( 16 mg/cc) and the total loading (-420 mg/cc), dyjg2release was modelled as a dispersed monolith and a 3.19 x 10 cm /h diffusion coefficient was calculated. 

Plasma concentrations of diclofenac sodium after application of the transbuccal delivery device (Figure 6) followed a different time course to that observed with the saturated solution. Plasma concentrations of the drug increased rapidly over the initial phase and achieved peak values of 2400-4000 ng/ml at 1 h after system application. Thereafter, the levels decreased slowly and converged to a mean value of 2250 ng/ml before the system was removed. Based on depletion analysis, 7.8 mg was delivered on average from the hydrogel discs over 4 h. 

Cross-linked versions of water-soluble polymers swollen in aqueous media are broadly referred to as hydrogels (52) and have a growing commercial utility in such applications as oxygen-permeable soft contact lenses (qv) (53) (Table 4) and controlled-release pharmaceutical drug delivery devices (54). Cross-linked PVP and selected copolymers fit this definition and are of interest because of the following structure/performance characteristics ... 

Figure 4.17 Schematic of pulsating drug delivery device based on feedback inhibition of glucose transport to glucose oxidase through a hydrogel membrane. Changes in permeability to glucose are accompanied by modulation of drug permeability. Reprinted from [97] with permission from American Institute of Physics.

Acrylated terminated multi-block micelle-forming biodegradable macromo-lecular hydrogels, (VI), prepared by Pathak [6], were used in drug delivery devices and as tissue coatings. 

The diffusion coefficients and translational movements of proteins are important in considering the release of proteins from hydrogel matrix devices and other delivery vehicles, and in membrane transport, as far as this can be considered to be a passive diffusion process. Changes in shape during membrane transport in a lipid environment may also have to be considered. Table 11.6 gives some values of diffusion coefficient of a number of therapeutic peptides and proteins. 

S. Ranjata, "Synthesis of Gum arabic based hydrogels and their applications as superabsorbents, flocculants and controlled drug delivery devices" Ph.D. Thesis, National Institute of Technology, Hamirpur, Himachal Pradesh, 2010. 

---