Formulation and evaluation of rofecoxib tablets in comparison with marketed product

ABSTRACT

Rofecoxib [ROF] is an analgesic anti-inflammatory drug. It is a selective inhibitor of cyclooxygenase enzyme [Cox-2]. The aim of this work was to prepare and evaluate ROF tablets with higher dissolution rates and higher activity and to compare them with the marketed product. Direct compression technique was adopted for preparation of ROF tablets using different excipients namely; Sta-Rx starch 1500 or mixture of anhydrous lactose and microcrystalline cellulose Avicel pH 101 [11 w/w. ratio]. The effect of co-grinding method of ROF with either-polyvinyl pyro-lidone [PVP] 40000 or Avicel pH 101 in a ratio of 15 w/w on the drug release from the prepared tablets was also studied. All the tablet quality control tests and the thermal behavior were studied. The anti-inflammatory activity was also studied in rats using paw-edema method and the results were investigated by statistical analysis using ANOVA test at the level of significance [P = 0.05]. All formulations of ROF tablets showed good mechanical properties and complied with the USP XXV pharmacopeial standard requirements for uniformity of dosage units and friability. Differential scanning calorimetry showed transformation of the drug to the amorphous form. Formulae No. 2, 3 [containing co-ground mixture of the drug with either PVP 40000 or Avicel pH 101 and Sta-Rx starch 1500] gave higher percentage of ROF release [t[50%] = 15, 9 min. respectively,] in comparison with the marketed product [t[50%] = 25 min]. It was found also that the prepared ROF tablets show superior anti-inflammatory activity in comparison with the marketed product upon analysis of data using ANOVA test