Absorption of ibuprofen coated by anhydrous silicic acid

We studied the dissolution and absorption of ibuprofen (IB) from a three-layer tablet: the 1st layer (CIB layer) consisted of IB which was coated with anhydrous silicic acid (CIB), the 2nd layer was bromovalerylurea and anhydrous caffeine, and the 3rd layer was bromovalerylurea and ethenzamide. Differential scanning calorimetry and powder X-ray diffraction studies showed that the crystallinity of IB was not influenced by the preparation of CIB. The dissolution and absorption of IB from the CIB layer of the three-layer tablet were compared with those of a commercial tablet. In a test solution at pH 1.2, the dissolution rate of IB from the CIB layer was higher than that from the commercial tablet; moreover, the time for peak concentration (Tmax) after administration of the CIB layer was significantly shorter. The Tmax of the CIB layer tablet was about 52 min, while that of the commercial tablet was about 103 min. The rapid dissolution and absorption of IB in the CIB layer may be due to enhanced permeation, disintegration and disaggregation of CIB.