rakesh grover - Academia.edu (original) (raw)
Related Authors
Universidad Nacional de Colombia (National University of Colombia)
Uploads
Papers by rakesh grover
Journal of Pharmaceutical Sciences, 1998
The potential of liquisolid systems to improve the dissolution properties of water-insoluble agen... more The potential of liquisolid systems to improve the dissolution properties of water-insoluble agents was investigated using hydrocortisone as the model medication. The in vitro release patterns of this very slightly water-soluble corticosteroid, formulated in directly compressed tablets and liquisolid compacts, were studied at different dissolution conditions. The new formulation technique of liquisolid compacts was used to convert liquid medications such as solutions or suspensions of hydrocortisone in propylene glycol, a nonvolatile liquid vehicle, into acceptably flowing and compressible powders by blending with selective powder excipients. Several liquisolid tablet formulations were prepared using a new mathematical model to calculate the appropriate quantities of powder and liquid ingredients required to produce acceptably flowing and compressible admixtures. Due to their increased wetting properties and surface of drug available for dissolution, liquisolid compacts demonstrated significantly higher drug release rates than those of conventionally made, directly compressed tablets containing micronized hydrocortisone. The in vitro drug dissolution rates of liquisolid tablets were found to be consistent and independent of the volume of dissolution medium used, in contrast to the plain tablets which exhibited declining drug release patterns with decreasing dissolution volumes. It has been also shown that the fraction of molecularly dispersed drug in the liquid medication of liquisolid systems is directly proportional to their hydrocortisone dissolution rates.
Drug Development and Industrial Pharmacy, 1999
The effects of powder substrate composition on the in vitro release properties of methyclothiazid... more The effects of powder substrate composition on the in vitro release properties of methyclothiazide liquisolid compacts were evaluated. The dissolution patterns of this water-insoluble drug formulated in liquisolid tablets were also compared to those of commercial products. According to the new liquisolid technique, liquid medications such as solutions or suspensions of water-insoluble drugs in suitable nonvolatile liquid vehicles can be converted into acceptably flowing and readily compressible powders by a simple admixture with certain powder substrates, which are selected powders referred to as the carrier and coating materials. Enhanced release profiles may be exhibited by such systems due to the increased wetting properties and surface of drug available for dissolution. Liquisolid tablets of methyclothiazide containing a 5% w/w drug solution in polyethylene glycol 400 were prepared using powder substrates of different excipient ratios. The release rates of such products were assessed using the USP dissolution test and were compared to those of their commercial counterparts. It was observed that maximum drug dissolution rates can be exhibited by systems that have powder substrates with optimum carrier-to-coating ratios. In addition, liquisolid tablets displayed significantly enhanced dissolution profiles compared to those of marketed products.
Journal of Pharmaceutical and Biomedical Analysis, 1998
A simple spectrophotometric procedure was developed and validated to indirectly assess the quanti... more A simple spectrophotometric procedure was developed and validated to indirectly assess the quantities of propylene glycol (PG) remaining in compressed liquid/powder admixtures. Such simplified quantitation may facilitate several testing procedures related to various aspects of formulation development and material testing of pharmaceutical powder excipients using various nonvolatile liquids as the diluents. In the present study, this new and simple approach for PG quantitation was developed as an integral part of a new method termed the liquisolid compressibility (LSC) test, used to characterize the compaction behavior of powder excipients. According to LSC testing, several admixtures of a nonvolatile liquid (in this case PG) and a powder, differing in their PG/powder weight ratio, are compressed in order to assess their compactabilities. The PG content of such compacts may then be directly quantitated by the USP gas chromatographic method or, indirectly, by this new simple spectrophotometric procedure. The new approach involves the addition of a dye marker to the PG prior to its incorporation into the powder. After compression, the PG amount remaining in the compacts may be determined by simply extracting the dye from the tablets and analyzing the extracts spectrophotometrically. In this manner, the dye content thus obtained may be extrapolated to the respective net amount of PG originally added as a dye/PG solution to the powder. Statistical comparison of the results obtained from both methods revealed almost absolute correlation.
Journal of Pharmaceutical Sciences, 1998
The potential of liquisolid systems to improve the dissolution properties of water-insoluble agen... more The potential of liquisolid systems to improve the dissolution properties of water-insoluble agents was investigated using hydrocortisone as the model medication. The in vitro release patterns of this very slightly water-soluble corticosteroid, formulated in directly compressed tablets and liquisolid compacts, were studied at different dissolution conditions. The new formulation technique of liquisolid compacts was used to convert liquid medications such as solutions or suspensions of hydrocortisone in propylene glycol, a nonvolatile liquid vehicle, into acceptably flowing and compressible powders by blending with selective powder excipients. Several liquisolid tablet formulations were prepared using a new mathematical model to calculate the appropriate quantities of powder and liquid ingredients required to produce acceptably flowing and compressible admixtures. Due to their increased wetting properties and surface of drug available for dissolution, liquisolid compacts demonstrated significantly higher drug release rates than those of conventionally made, directly compressed tablets containing micronized hydrocortisone. The in vitro drug dissolution rates of liquisolid tablets were found to be consistent and independent of the volume of dissolution medium used, in contrast to the plain tablets which exhibited declining drug release patterns with decreasing dissolution volumes. It has been also shown that the fraction of molecularly dispersed drug in the liquid medication of liquisolid systems is directly proportional to their hydrocortisone dissolution rates.
Drug Development and Industrial Pharmacy, 1999
The effects of powder substrate composition on the in vitro release properties of methyclothiazid... more The effects of powder substrate composition on the in vitro release properties of methyclothiazide liquisolid compacts were evaluated. The dissolution patterns of this water-insoluble drug formulated in liquisolid tablets were also compared to those of commercial products. According to the new liquisolid technique, liquid medications such as solutions or suspensions of water-insoluble drugs in suitable nonvolatile liquid vehicles can be converted into acceptably flowing and readily compressible powders by a simple admixture with certain powder substrates, which are selected powders referred to as the carrier and coating materials. Enhanced release profiles may be exhibited by such systems due to the increased wetting properties and surface of drug available for dissolution. Liquisolid tablets of methyclothiazide containing a 5% w/w drug solution in polyethylene glycol 400 were prepared using powder substrates of different excipient ratios. The release rates of such products were assessed using the USP dissolution test and were compared to those of their commercial counterparts. It was observed that maximum drug dissolution rates can be exhibited by systems that have powder substrates with optimum carrier-to-coating ratios. In addition, liquisolid tablets displayed significantly enhanced dissolution profiles compared to those of marketed products.
Journal of Pharmaceutical and Biomedical Analysis, 1998
A simple spectrophotometric procedure was developed and validated to indirectly assess the quanti... more A simple spectrophotometric procedure was developed and validated to indirectly assess the quantities of propylene glycol (PG) remaining in compressed liquid/powder admixtures. Such simplified quantitation may facilitate several testing procedures related to various aspects of formulation development and material testing of pharmaceutical powder excipients using various nonvolatile liquids as the diluents. In the present study, this new and simple approach for PG quantitation was developed as an integral part of a new method termed the liquisolid compressibility (LSC) test, used to characterize the compaction behavior of powder excipients. According to LSC testing, several admixtures of a nonvolatile liquid (in this case PG) and a powder, differing in their PG/powder weight ratio, are compressed in order to assess their compactabilities. The PG content of such compacts may then be directly quantitated by the USP gas chromatographic method or, indirectly, by this new simple spectrophotometric procedure. The new approach involves the addition of a dye marker to the PG prior to its incorporation into the powder. After compression, the PG amount remaining in the compacts may be determined by simply extracting the dye from the tablets and analyzing the extracts spectrophotometrically. In this manner, the dye content thus obtained may be extrapolated to the respective net amount of PG originally added as a dye/PG solution to the powder. Statistical comparison of the results obtained from both methods revealed almost absolute correlation.