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Mansoura Journal of Pharmaceutical Sciences. 2006; 22 (1): 38-55
in English | IMEMR | ID: emr-197709

ABSTRACT

The incorporation of a drug in a carrier by either solvent evaporation or melt embedding may result in either a solid solution or a solid suspension of the active ingredient within the carrier material. Consequently, solid dispersions [SD] of rofecoxib containing varying concentrations of either polyethylene glycol [PEG] 35000 or urea were prepared in an attempt to improve the solubility and dissolution rate of rofecoxib. Moreover, the influence of the PEG chain length on the dissolution characteristics of the drug was also investigated. The physical characteristics of rofecoxib, physical mixtures iPM] and SDs were investigated by a variety of analytical methods including fourier transform infrarrd spectroscopy [FTIR], powder X-ray diffraction [XRD] and differential scanning calorimetry [DSC]. For testing the applicability to formulate in a solid dosage form, 1:9 rofecoxib SD with PEG 3500C was formulated in the form of hard gelatin capsules. The obtained results showed that the dissolution rates of PMs were higher than that of pure drug. However, SDs exhibited higher dissolution rates than those of PMs. compared to urea, PEG 35000 had the most influential effect on enhancing the rate and extent of rofecoxib dissolution from their systems. The drug to carrier ratio in the prepared SDs was one of the main influences on the performance of a SD. In addition, it was found at the fusion method was more efficient than the solvent method in improving the dissolution of the drug from the investigated SDs. Regarding the effect of the pH of the dissolution medium, it was found that the pH change had negligible effect on the release of the drug from its dispersions with PEG 35000. The FTIR spectra revealed an interaction between rofecoxib and PEG 35000. Besides, the amorphous form of rofecoxib found in powdered SDs, as demonstrated by XRD and DSC, may explain the better dissolution rate from SD

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