Application of crustacean chitin as a co-diluent in direct compression of tablets.

A "simplex-centroid mixture design" was used to study the direct-compression properties of binary and ternary mixtures of chitin and two cellulosic direct-compression diluents. Native milled and fractioned (125-250 microm) crustacean chitin of lobster origin was blended with microcrystalline cellulose, MCC (Avicel PH 102) and spray-dried lactose-cellulose, SDLC Cellactose (composed of a spray-dried mixture of alpha-lactose monohydrate 75% and cellulose powder 25%). An instrumented single-punch tablet machine was used for tablet compactions.

Estimation of the percolation thresholds in ternary lobenzarit disodium-dextran-HPMC hydrophilic matrices tablets: effects of initial porosity.

The aim of this work is to estimate the excipient percolation threshold for a new combined matrix native dextran (DT), series B110-1-2 (Mw 2 x 10(6)): HPMC K4M CR: lobenzarit disodium (LBD) system and demonstrate the advantages of this ternary system with respect to previously reported binary dextran:LBD and HPMC:LBD tablets. The formulations studied were prepared with different amounts of excipient (DT:HPMC, 4:1 (wt/wt) for all tablets and relative polymer/drug particle size of 4.17) in the range of 10-70% (wt/wt).

Direct compression properties of chitin and chitosan.

Deformation and compaction properties of native amino poly-saccharides chitin and chitosan were studied and compared with those obtained with established pharmaceutical direct compression excipients. An instrumented single-punch tablet machine was used for tablet compaction. The following compression parameters were evaluated: a ratio of crushing strength and compression pressure, plasticity and elasticity factor (PF and EF), tensile strength and R-value.

Estimation of the percolation thresholds in lobenzarit disodium native dextran matrix tablets.

The objective of the present work is to estimate for the first time the percolation threshold of a new series of dextran (native dextran of high molecular weight [B110-1-2, Mw = 2 x 10(6)]), in matrices of lobenzarit disodium (LBD) and to apply the obtained result to the design of hydrophilic matrices for the controlled delivery of this drug. The formulations studied were prepared with different amounts of excipient in the range of 20% to 70% wt/wt. Dissolution studies were performed using the paddle method (100 rpm) and one face water uptake measurements were performed using a modified Enslin apparatus.

Subcoating with Kollidon VA 64 as water barrier in a new combined native dextran/HPMC-cetyl alcohol controlled release tablet.

A novel oral controlled delivery system for propranolol hydrochloride (PPL) was developed and optimized using wet granulation process. We are studying the ability of subcoating with Kollidon VA 64 as a barrier to water penetration in matrix cores combined hydrophilic (native dextran-HPMC)/hydrophobic (cetyl alcohol) prior to film coating with Opradry II-YS-30-18056. The copovidone (i.

A sugar cane native dextran as an innovative functional excipient for the development of pharmaceutical tablets.

We reported the physical chemical characterization of a new series of native dextran (B110-1-2). The chemical structure of the polymer was characterized by IR, (1)H and (13)C NMR spectroscopy and compared with that of a commercial native dextran B512-F obtained from Sigma Company. Molecular weights of the product and different commercial dextran fractions of Leuconostoc mesenteroides from 43000 to 170000 average molecular weight (M(w)) were established by the analysis of intrinsic viscosity in aqueous solutions and compared with those obtained by gel permeation chromatography (GPC).

Development and optimization of a novel sustained-release dextran tablet formulation for propranolol hydrochloride.

A novel oral controlled delivery system for propranolol hydrochloride (PPL) was developed and optimized. The in vitro dissolution profiles of sustained-release matrix tablets of racemic PPL were determined and compared with the United States Pharmacopeia (USP) tolerance specifications for Propranolol Hydrochloride Extended-Release Capsules. The influence of matrix forming agents (native dextran, hydroxypropyl methylcellulose (HPMC), cetyl alcohol) and binary mixtures of them on PPL release in vitro was investigated.

Physical solid-state properties and dissolution of sustained-release matrices of polyvinylacetate.

Solid-state compatibility and in vitro dissolution of direct-compressed sustained-release matrices of polyvinylacetate (PVAc) and polyvinylpyrrolidone (PVP) containing ibuprofen as a model drug were studied. Polyvinylalcohol (PVA) was used as an alternative water-soluble polymer to PVP. Differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) were used for characterizing solid-state polymer-polymer and drug-polymer interactions.

Physical stability and moisture sorption of aqueous chitosan-amylose starch films plasticized with polyols.

The short-term stability and the water sorption of films prepared from binary mixtures of chitosan and native amylose maize starch (Hylon VII) were evaluated using free films. The aqueous polymer solutions of the free films contained 2% (w/w) film formers, glycerol, or erythritol as a plasticizer, as well as acetic acid (1%) and purified water. Characterization of the present fresh and conditioned film formers and free films was done using X-ray diffraction analysis, determination of moisture sorption isotherms, and near infrared spectroscopy.

Solid-state and mechanical properties of aqueous chitosan-amylose starch films plasticized with polyols.

The film-forming ability of chitosan and binary mixtures of chitosan and native amylose corn starch (Hylon VII) was evaluated with free films prepared by a casting/solvent evaporation method. Unplasticized and plasticized free chitosan films in aqueous acetic acid and respective films containing a mixture of chitosan and native amylose starch in acetic acid were prepared. Glycerol, sorbitol, and i-erythritol were used as plasticizers.