Biomedical subjects

K V Ramana Murthy

Publications and source records attributed to K V Ramana Murthy.

5 recordsLinked to original sources

PubMed2003

Nimesulide-modified gum karaya solid mixtures: preparation, characterization, and formulation development.

Solid mixtures of nimesulide (NS) and modified gum karaya (MGK) were prepared to improve the dissolution rate of NS. The effect of drug-carrier ratio on dissolution rate of NS was investigated by preparing the solid mixtures of different ratios by cogrinding method. Solid mixtures were also prepared by physical mixing, kneading, and solid dispersion techniques to study the influence of method of preparation. Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), and equilibrium solubility studies were performed to explain the results of in vitro dissolution rate studies. It was clearly evident from the results that the NS dissolution rate was dependent on the concentration of MGK in the solid mixtures, and optimum weight ratio was found to be 1:4 (NS:MGK). Though the dissolution rate of NS from all solid mixtures prepared by different methods improved significantly, maximum improvement in dissolution rate was observed with solid dispersions. The order of methods basing on their effect on dissolution efficiency is solid dispersion > kneading > cogrinding > physical mixing > pure NS. Tablets of pure drug and solid mixtures (1:4 w/w, NS:MGK) were prepared. Though the best results from the dissolution test were obtained for the tablets containing solid dispersions, tablets containing cogrinding mixture were found to be suitable, from a practical point of view, for commercialization.

Adjuvants, Pharmaceutic↗

PubMed2002

Evaluation of modified gum karaya as carrier for the dissolution enhancement of poorly water-soluble drug nimodipine.

Modified gum karaya (MGK), a recently developed excipient was evaluated as carrier for dissolution enhancement of poorly soluble drug, nimodipine (NM). The advantages of MGK over the parent gum karaya (GK) were illustrated by differences in the in vitro dissolution profiles of respective solid mixtures prepared by co-grinding technique. The influence of process variable, such as polysaccharide concentration and method of preparation of solid mixture on dissolution rate was studied. Solubility studies were also performed to explain the differences in dissolution rate. Solid mixtures were characterized by differential scanning calorimetry (DSC), X-ray diffraction studies (XRD) and scanning electron microscopy (SEM). The dissolution rate of NM was increased as the MGK concentration increased and optimum ratio was found to be 1:9 w/w ratio (NM:MGK). It is found that method of preparation of solid mixtures was significantly effected the dissolution rate of NM from solid mixtures. The order of method of preparation in according to their Dissolution Efficiency is physical mixture < co-grinding mixture < swollen carrier mixture < kneading mixture (water as kneading agent) < kneading mixture (70% v/v ethanol as kneading agent) < solid dispersion. Though, the solid mixtures prepared by other methods like solid dispersion, swollen carrier mixture and kneading technique gave faster release, co-grinding mixture prepared in 1:9 w/w ratio (NM:MGK) was found to exhibit a significant improvement in dissolution rate without requiring addition of organic solvents or high temperatures for its preparation and the process is less cumbersome. Hence, co-grinding technique appears to be more easier and the most convenient method from a practical point of view.

Acids↗

PubMed2002

Studies on rifampicin release from ethylcellulose coated nonpareil beads.

The rifampicin release studies from ethylcellulose coated nonpareil beads were studied. Propylene glycol and Castor oil were used as plasticizers. The in vitro dissolution studies revealed that the release rate is inversely proportional to percent of coating thickness. The release rate also depends on the type of plasticizer used in the coating polymer. The mechanism of drug release follows Higuchi diffusion model. Water vapour permeation studies indicated that the water vapour transport rate through free films is directly related to the drug release rate. DSC thermograms and IR spectras revealed that there is no interaction between rifampicin and other additives. SEM photographs of coated beads, before dissolution and after dissolution, also indicates that the drug release mechanism follows diffusion model.

Cellulose↗

PubMed2001

Correlation of "in vitro" release and "in vivo" absorption characteristics of rifampicin from ethylcellulose coated nonpareil beads.

The purpose of this study was to investigate the possibility to develop different levels of correlation between in vitro dissolution parameters and in vivo pharmacokinetic parameters for three rifampicin formulations. A level A correlation of in vitro release and in vivo absorption could be obtained for individual plasma level data by means of the Wagner and Nelson method. Linear correlation could be obtained when percent dose released in vitro was plotted vs percent dose absorbed in vivo with correlation coefficients between 0.954,0.983 and 0.997 for the formulations studied. A second level correlation between mean in vitro dissolution time (MDT) and mean in vivo residence time (MRT) was performed with a correlation coefficient of 0.536,0.420 and 0.335. Finally, it was also possible to establish a good in vitro-in vivo correlation when the T(50%hrs) (time taken to release 50% of rifampicin) in vitro and C(max),T(max) or AUC in vivo were compared.

Absorption↗

PubMedDate not supplied

Studies on the applicability of tamarind kernel powder as a carrier in the dissolution enhancement of poorly water soluble drug, celecoxib.

In the present investigation, tamarind kernel powder (TP) was evaluated for its suitability as a carrier to improve the dissolution rate of poorly water-soluble drug, celecoxib (CC). The influence of polysaccharide concentration and method of preparation of solid mixtures on dissolution rate was investigated. Solid mixtures of CC and TP were prepared in different ratios (1:1, 1:4 & 1:9 w/w, CC:TP) using co-grinding technique to test the effect of polysac-charide concentration. Four different methods namely (i) physical mixing method (ii) co-grinding method (iii) kneading method and (iv) solvent deposition method were used to assess the effect of method of preparation. Solid mixtures were characterized by Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD) studies and solubility studies. Dissolution rate of CC was increased as the TP concentration increased and optimum weight ratio was found to be 1:4 (CC:TP). It was found that method of preparation of solid mixtures significantly effected the dissolution rate of CC from solid mixtures. The order of products basing on dissolution efficency is solvent deposition > co-grinding > kneading > physical mixing > pure CC. Among all the methods, though the solvent deposition technique improved the dissolution rate to maximum, co-grinding technique was found to be suitable from practical point of view and commercialization.

Calorimetry, Differential Scanning↗