Formulation and evaluation of rofecoxib capsules

ABSTRACT

Rofecoxib [ROF] is an analgesic, antipyretic and anti-inflammatory drug. It is a selective inhibitor of cyclooxygenase enzyme [Cox-2 inhibitor]. The aim of this work was to formulate and evaluate ROF capsules and compare them with a commercial ROF product. The ROF capsules were prepared using different excipients namely Sta-Rx starch 1500, cellactose, anhydrous lactose and tablettose. Compatibility of the drug with the used excipients was studied by differential scanning calorimetry. The effect of cogrinding of ROF with either PVP 40000 or Avicel PH 101 in the ratio of 15 w/w on the drug release from the prepared capsules was also studied. Differential scanning calorimetry and x-ray diffraction studies showed reduction in crystallinity or conversion of the drug to an amorphous form upon grinding with either PVP 40000 or Avicel PH 101 respectively. All formulae of ROF capsules complied with the USP XXV requirements for uniformity of dosage units. Formulae No. 6 and 7 containing ground mixture of the drug with either PVP 4000 or Avicel PH 101 in a ratio of 15 drug to carrier and Sta-Rx starch 1500 as diluent gave a higher dissolution rate of ROF [t[50%] = 5 and 9 min., respectively] in comparison with the commercial ROF product Rhumacure [t[50%] = 25 min.] Moreover; the anti-inflammatory activity was studied in rats using paw-edema method and the results obtained were analyzed using ANOVA test at the level of significance [P capsules show superior anti-inflammatory activity in comparison with the commercial ROF product