Papers by Brijesh Vishwakarma
Biochemistry, 2010
Melittin is a good model antimicrobial peptide to understand the basis of its lytic activities ag... more Melittin is a good model antimicrobial peptide to understand the basis of its lytic activities against bacteria and mammalian cells. Novel analogues of melittin were designed by substituting the leucine residue(s) at the "d" and "a" positions of its previously identified leucine zipper motif. A scrambled peptide having the same composition of melittin with altered leucine zipper sequence was also designed. The analogues of melittin including the scrambled peptide showed a drastic reduction in cytotoxicity though they exhibited comparable bactericidal activities. Only melittin but not its analogues localized strongly onto hRBCs and formed pores of ∼2.2-3.4 nm. However, melittin and its analogues localized similarly onto Escherichia coli and formed pores of varying sizes as tested onto Bacillus megaterium. The data showed that the substitution of hydrophobic leucine residue(s) by lesser hydrophobic alanine residue(s) in the leucine zipper sequence of melittin disturbed its pore-forming activity and mechanism only in hRBCs but not in the tested bacteria.
Asian Journal of Pharmaceutical Sciences, 2013
Cefuroxime axetil (CA) is an ester prodrug of cefuroxime with an unpleasant taste when administra... more Cefuroxime axetil (CA) is an ester prodrug of cefuroxime with an unpleasant taste when administrated orally. This work was to mask the bitter taste of CA and enhance its oral bioavailability. Dry suspensions were prepared by means of wet granulation method and solid dispersion method. Binders, suspending agents and other compositions involved in the formulation were optimized. The differential scanning calorimetry (DSC) analysis indicated that CA was amorphous in the solid dispersion with stearic acid as the carrier, which contributed to an improvement of the dissolution rate. Taste evaluation was performed by three volunteers and taste masking was successfully achieved by the methods mentioned above. A pH 7.0 phosphate buffer was adopted to study the in vitro dissolution performance of the three formulations, i.e., two self-made dry suspensions and the commercial one. With a better release characteristic and a satisfying taste masking ability, the solid dispersion suspension was selected as the optimal formulation for the further pharmacokinetic study in beagle dogs. The values of C max and AUC 0e12 for the solid dispersion suspension were about 1.78-fold and 2.17-fold higher than these of reference suspension, respectively. The obtained results demonstrated that the solid dispersion can efficiently mask the bitter taste of CA and significantly enhance its oral bioavailability.
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Papers by Brijesh Vishwakarma