V. Ramesh Babu

Developments in polymeric devices for oral insulin delivery

Background: Development of improved oral insulin administration is necessary for the treatment of diabetes mellitus, to overcome the problem of daily subcutaneous injections. The vast amount of literature data on oral insulin delivery prompted us to cover this area in a review. Objective: Insulin delivery using polymeric devices is discussed, with an ultimate aim of addressing the technological development in this area. Methods: The development of oral delivery devices for insulin using hydrogels and micro/nanoparticles is discussed with reference to polymers. These efforts must be directed to increase the residence time of insulin near the intestinal absorptive cells. Results/conclusion: The published results on oral insulin delivery devices, particularly on inter-polymer complexes of the grafted copolymers, are discussed in greater depth. The use of absorption enhancers like cyclodextrins, bile salts and surfactants is covered. The state-of-the-art technology and challenges in this area are discussed, with typical examples.

Development of chitosan-guar gum semi-interpenetrating polymer network microspheres for controlled release of cefadroxil

Blend microspheres of chitosan (CS) and guar gum (GG) have been prepared using the water-in-oil (w/o) emulsion method. Cefadroxil was loaded into the microspheres and cross-linked with glutaraldehyde, leading to the formation of a semi-interpenetrating polymer network (IPN) structure. The microspheres have been characterized by scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. Scanning electron micrographs showed the formation of non-uniform microspheres with the rough surface. X-ray diffraction and differential scanning calorimetry studies of the plain and the drug-loaded microspheres indicated that drug is dispersed at the molecular level in the semi-IPN matrix. In vitro dissolution experiments performed in pH 7.4 buffer medium indicated a sustained and controlled release of cefadroxil from semi-IPN microspheres up to 10 h. The amount of drug loaded into microspheres, CS-GG composition of the blend and the amount of cross-linking agent used have shown dependencies on the release of cefadroxil from the semi-IPN microspheres.

Sodium alginate-TiO2 mixed matrix membranes for pervaporation dehydration of tetrahydrofuran and isopropanol

Mixed matrix polymer membranes containing nanosized (21 nm) TiO2 particles dispersed in sodium alginate (NaAlg) have been prepared by solution casting and cross-linking with glutaraldehyde. These membranes were tested for pervaporation (PV) dehydration of tetrahydrofuran (THF) and isopropanol from their aqueous solutions at 30°C. Results have been compared with plain cross-linked NaAlg membrane. Plain cross-linked NaAlg membrane could remove up to a maximum of 97 wt% of water at higher feed water concentrations of the feed with considerably much lower selectivity. Infinite selectivity values with reasonable fluxes were observed for the mixed matrix membranes of NaAlg in the investigated feed compositions of 5–15 wt% water containing THF and 10–20 wt% of water containing isopropanol feed mixtures. Fluxes of NaAlg-TiO2 mixed matrix membranes are slightly lower than those of plain the NaAlg membrane for the investigated range of feed water compositions.

Preparation and characterization of atenolol-loaded cellulose acetate butyrate-poly(vinyl pyrrolidone) blend microspheres: in vitro release studies

Cellulose acetate butyrate-poly(vinyl pyrrolidone) (CAB-PVP) blend microspheres were prepared using the solvent evaporation technique using poly(vinyl alcohol) as an emulsifying agent. Atenolol (ATNL), an antihypertensive drug, was successfully loaded into these microspheres. Effect of experimental variables such as CAB/PVP ratio on ATNL encapsulation efficiency, release rate, size and morphology of the microspheres has been investigated. ATNL-loaded microspheres were analyzed using differential scanning calorimetry to investigate the crystalline nature of ATNL after encapsulation. DSC results indicated a non-uniform dispersion of ATNL in CAB-PVP blend matrix. Scanning electron micrographs indicated the formation of spherical microspheres. Mean particle size of the microspheres, as measured by the laser light scattering technique, ranged between 100 and 120 μm. An encapsulation of about 80% of ATNL was achieved. In vitro dissolution experiments performed in pH 7.4 buffer medium indicated the controlled release of atenolol from the blend microspheres up to 10 h.