Triterpenoid saponins complex of biological origin, escin, exhibits significant clinical activity in chronic venous insufficiency, skin inflammation, epidermal abrasions, allergic dermatitis, and acute impact injuries, especially in topical application. The aim of the study is the comparison of various hydrogel formulations, as carriers for a horse chestnut seed extract (EH). Methylcellulose (MC), two polyacrylic acid derivatives (PA1 and PA2), and polyacrylate crosspolymer 11 (PC-11) were employed. The release rates of EH were examined and a comparison with the Weibull model equation was performed. Application of MC as the carrier in the hydrogel preparation resulted in fast release rate of EH, whereas in the case of the hydrogel composed with PC-11 the release was rather prolonged. Applied Weibull function adhered best to the experimental data. Due to the evaluated shape parameterβ, in the Weibull equation, the systems under study released the active compound according to the Fickian diffusion.
The copolymers of N-isopropyl acrylamide (NIPA) have been studied extensively as drug carriers for antibacterial, cardiovascular, cytostatic, local anesthetic, and nonsteroidal anti-inflammatory agents, to deliver the required therapeutic effect. The aim of this work was to evaluate the effect of a series of newly synthesized thermosensitive polymeric NIPA derivatives on the release rate of naproxen sodium (NS) from hydrogels composed of hydroxypropyl methylcellulose (HPMC). NIPA derivatives P1-P4 were synthesized by precipitation polymerization without an emulsifier, and their structures were evaluated by NMR spectroscopy. Four formulations were prepared with NS (FP1-FP4), and rate of NS release from these systems was evaluated using a modified pharmacopeial method at 22 and 42°C. The release rate of NS followed a similar trend in all four of the formulations assessed at 22°C, which was the same as the reference formulation. However, the release rate of NS at 42°C was clearly faster in the samples containing the thermosensitive polymers P1-P4 compared with the reference formulation. These results clearly demonstrate that the use of thermosensitive polymeric derivatives of NIPA can increase the release rate of NS from hydrophilic gels based on HPMC.Graphical Abstract Diversity of release courses of naproxen sodium evaluated in formulation containing poly(ethylene glycol) dimethacrylate (PDA, left), and comparison of half-release times (T HR , right) of naproxen sodium formulations containing various thermosensitive polymers P1-P4.
Nanospheres and microspheres are known as a multipurpose compounds and are used in various branches of science. Recent controlled delivery systems for drugs are also based on poly-micro and nanospheres. In our study we describe an investigation of the influence of thermosensitive polymer N-isopropylacrylamide (NIPA) on the release of the drug naproxen sodium (NS) with a hydrogel hydroxypropyl methylcellulose (HPMC) base. The hydrodynamic diameter (D H ) of the obtained polymer was measured by using dynamic light scattering (DLS) at a wavelength of 678 nm. Hydrogel formulations of NS were prepared in a specific way ex tempore. NS was sprinkled on the surface of a distilled water, then polymer soluted in water was added. Afterward, HPMC was affixed to the solution. Prepared samples were stored at room temperature for 24 h. Release tests showed that modification of thevcross-linker type influenced the properties of synthesized polymeric particles. The NIPA derivatives obtained via surfactant free precipitation polymerization (SFPP) may be formulated as hydrogel preparations using HPMC. The obtained formulations presented varied half-release times, depending on the type of applied NIPA derivatives in hydrogel formulations. At 18 • C, the release rates were lower comparing to the reference HPMC hydrogel, whereas at 42 • C, the release rates were significantly higher. The synthesized thermosensitive polymers enabled temperature-triggered release of NS.
Poly-N-isopropylacrylamide (polyNIPA) is an extensively studied polymer in the field of controlled drug delivery. PolyNIPA contains carbonyl and amide groups along a hydrophobic chain. In an aqueous environment, crosslinked polyNIPA forms a gel characterized by a reversible volume phase transition temperature (VPTT), in response to changes in the external environment excited by the temperature factor. NIPA-based polymers were synthesized by a surfactant-free precipitation polymerization (SFPP) method at a temperature of 70 °C using the free radical initiator potassium persulfate (KPS) and at 35 °C using redox initiator system KPS with N,N,N’,N’-tetramethylethylenediamine (TEMED). The synthesized products were evaluated via dynamic light scattering (DLS), nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR). The chemical structure, molecular mass, and hydrodynamic diameter of obtained particles, as well as the effects of synthesized polymers on the release of the active substance, naproxen sodium (NS), from hydroxypropyl methyl cellulose (HPMC)-based hydrogels were assessed. The use of the TEMED activator affected the particle size, as well as the release kinetics of NS. The insertion of TEMED into reactant mixtures may be applied to modify the release kinetics of NS from hydrogel preparations.
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