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Biomedical subjects

A K Dorle

Publications and source records attributed to A K Dorle.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

A novel method for preparation of Eudragit RL microcapsules.

A novel technique for the preparation of Eudragit RL microcapsules is described. The technique is based on the principle of solvent evaporation. Diclofenac sodium is used as a model drug for encapsulation. A solution of drug and Eudragit RL dissolved in acetone-isopropyl alcohol (1:1) is sprayed in liquid paraffin. The microcapsules obtained were uniform and free flowing particles. The release rate was more sustained by increasing the polymer concentration. The experimental procedure promises a rapid and convenient method for the preparation of Eudragit RL-microcapsules.

2-Propanol↗
PubMedDate not supplied

Study of rosin glycerol esters as microencapsulating materials.

Rosin esters were prepared by heating rosin with glycerol and intermediate reaction products with different acid values were withdrawn. Salicylic acid granules were encapsulated using a 10 per cent solution of rosin esters in acetone. The coated microcapsules were evaluated for moisture absorption, flow properties and dissolution studies. The results showed that rosin and rosin-glycerol intermediates with acid values of 122, 105 and 55 had excellent moisture protection properties. Dissolution studies showed that these could be used for delayed release of drug.

Drug Compounding↗
PubMedDate not supplied

Effect of pH on the release characteristics of pentaestergum microcapsules and a study of dissolution kinetics.

Rosin and rosin esters have excellent film-forming properties. Pentaerythritol-rosin ester (penta-ester gum) is found to be useful as moisture-protecting material with delayed release of drug. This communication relates the effect of pH on the release characteristics of a drug from penta-ester gum coated microcapsules. Salicylic acid granules were encapsulated using a 10 per cent solution of penta-ester gum in acetone. The microcapsules were evaluated for their drug release characteristics. Various pH media (pH 1.2, 3.0, 5.0, 7.2 and 8.0) were used. The results showed that penta-ester gum exhibits excellent resistance to higher pH levels and can be used for the sustained release of the drug. Dissolution rate constants were calculated and they agree with the assumption of Hixson and Crowell's cube-root equation.

Drug Compounding↗
PubMedDate not supplied

A study on the dielectric constant of microcapsules during ageing.

Gelatin and methylcellulose microcapsules with and without sulphadiazine were compressed into compacts. The dielectric constant of these compacts was measured at regular intervals during ageing at 45 degrees C. An initial sharp fall in dielectric constant is followed by a progressive increase. Dielectric constant could be a parameter to study the changes occurring in microcapsules during ageing.

Capsules↗
PubMedDate not supplied

Study of shellac glycerol esters as microencapsulating materials.

Shellac esters were prepared by heating shellac with glycerol and intermediate reaction products were withdrawn. Salicyclic acid granules were encapsulated using a 20 per cent w/v alcoholic solution of shellac and shellac esters. The coated microcapsules were evaluated for moisture absorption, flow properties, and dissolution studies. The drug release from coated granules was seen to depend upon the acid value of the esters. Results indicate that shellac esters could be better encapsulating material than shellac in sustained release formulation.

Capsules↗
PubMedDate not supplied

Evaluation of compressibility of pentaestergum coated aspirin microcapsules.

We have earlier reported the usefulness of the pentaerythritol rosin ester (pentaestergum) as a coating material, its dissolution kinetics and in vivo release studies in dogs. The present communication deals with the compressibility of the pentaestergum-coated aspirin microcapsules. The microcapsules were prepared by the pan-coating method described earlier. These were compressed into the tablets using a single punch machine. The tablets were evaluated for hardness, friability loss, disintegration time and dissolution studies. The results showed that there were significant differences in the release characteristics from the microcapsules and the compressed tablets. The effect of 5 per cent starch as a disintegrating agent in the tablet formulation was also studied. The results showed that the tablets can be a suitable dosage form for pentaestergum-coated microcapsules to give a delayed drug release.

Aspirin↗
PubMedDate not supplied

Release kinetic study of RHPC coated aspirin microcapsules.

The present communication deals with the study of the effect of pH on the drug release characteristics and the drug release kinetic from the RHPC (Rosin Hard Paraffin Combination) coated aspirin microcapsules. For the purpose of the present study the aspirin microcapsules were prepared by pan coating method imparting 15 coats using 10 per cent RHPC solution in acetone. A standard coating procedure was used to coat the aspirin granules. Dissolution studies were carried out in media with different pH. To get a clear picture drug release studies were conducted in each media for 3 h. The results showed that the RHPC films were resistant to acidic pH releasing less than 5 per cent and 15 per cent drug in 3 h in pH 1.2 and 3.0 respectively. The T 50% in pH 5.0 media was 163 min. The drug was released very quickly in pH 7.2 and 8.0. The release kinetic study showed that the release followed the classical first order pattern though the coated microcapsules used to be intact during the dissolution process, in case of the acidic pH media. The release kinetic was changed when the pH of the dissolution media was 7.2 and above. It was found that during the dissolution process the granules undergo erosion and the release mechanism does not follow a single process.

Aspirin↗
PubMedDate not supplied

Effect of solvents on the characteristics of rosin walled microcapsules prepared by a solvent evaporation technique.

Rosin microcapsules were prepared by a solvent evaporation technique using solvents with different rates of evaporation. Sulphadiazine was used as a model drug. The microcapsules were studied for their size, drug content, wall thickness, surface characteristics and in vitro release. The mean diameter increased and the drug content decreased as the rate of evaporation of the solvent increased. Fast evaporating solvents produced thick walled microcapsules with innumerable surface pores/cracks compared with slow evaporating solvents.

Capsules↗
PubMedDate not supplied

A study on the zeta potential of microcapsules during ageing.

Gelatin, methylcellulose and agar microcapsules were prepared with and without suphadiazine. The zeta potential of these microcapsules was measured at regular intervals during ageing at 45 degrees C. An initial sharp rise in zeta potential is followed by a progressive decrease. Zeta potential could prove to be a useful parameter to study the changes occurring in the encapsulating material of microcapsules during ageing.

Capsules↗
PubMedDate not supplied

A new technique for the encapsulation of water insoluble drugs using ethyl cellulose.

A new technique for encapsulation of water insoluble drugs has been developed utilizing ethyl cellulose as a wall forming material. Ethyl cellulose was dissolved in a water immiscible, volatile organic solvent, containing sulphadiazine as a model drug. This dispersion was emulsified into an aqueous bentonite suspension and phase separation was induced by solvent evaporation. The effect of bentonite concentration, core to coat ratio, organic solvent, speed of agitation and temperature was studied with respect to the microcapsule size and size distribution, drug content, in vitro release and surface characteristics.

Bentonite↗
PubMedDate not supplied

Study of some improved shellac derivatives as microencapsulating materials.

Shellac was chemically modified to alter its permeability and to prevent its 'after hardening'. Various shellac derivatives such as with succinic anhydride, phthalic anhydride, ethylenediamine and myristic acid were prepared. Salicylic acid granules were coated and evaluated for flow properties, moisture absorption and release characteristics before and after ageing. These derivatives imparted better flow properties and showed excellent ageing properties.

Drug Compounding↗
PubMedDate not supplied

Release kinetics of drugs from rosin-glycerol ester microcapsules prepared by solvent evaporation technique.

Rosin-glycerol ester microcapsules containing sulphadiazine were prepared by solvent evaporation technique. The goodness of fit of the release data was tested with first order, Higuchi matrix model and Hixon-Crowell cube root law. All these models were sufficiently linear. Application of the differential rate treatment showed that release from most of the microcapsules followed first order equation. Whereas up to 40-50 per cent of release, a zero order, membrane controlled kinetics was observed, the release is apparently first order under nonsteady, state conditions.

Capsules↗
PubMedDate not supplied

Study of abietic acid glycerol derivatives as microencapsulating materials.

Abietic acid (85 per cent pure) was extracted from rosin N Grade and further standardized. Abietic acid derivatives were prepared by heating abietic acid with glycerol and intermediate reaction products with different acid values were collected. Salicylic acid granules were encapsulated using a 10 per cent solution of abietic acid and its derivatives by standard spray pan technique. The coated microcapsules were evaluated for moisture absorption, dissolution and flow properties. The result showed that abietic acid glycerol derivatives, AaG-54 and AaG-20 had better moisture protection properties. Dissolution studies indicate that these derivatives could be used for delayed release of drugs.

Abietanes↗