**2.2.6 Micromeritic properties**

The size of agglomerates was determined by microscopic method using stage and eyepiece micrometers. The shape of the agglomerates was observed under an optical microscope (×60 magnification) attached to a computer. Flowability of untreated carvedilol and agglomerates was assessed by determination of angle of repose, Carr's index (CI) and Hausner's ratio (HR) (Wells, 2002). Angle of repose was determined by fixed funnel method (Martin et al., 2002). The mean of three determinations was reported. The CI and HR were calculated from the loose and tapped densities. Tapped density was determined by tapping the samples into a 10 ml measuring cylinder. The CI and HR were calculated according to the following equation 1 and 2.

$$\text{C.I.} = \frac{\text{Tapped density - Bulk density}}{\text{Tapped density}} \times 100\tag{1}$$

$$\text{H.R.} = \frac{\text{Tappped density}}{\text{Bulk density}} \tag{2}$$

#### **2.2.7 Solubility studies**

A quantity of crystals (about 100 mg) was shaken with 10 mL distilled water in stoppered conical flask at incubator shaker for 24 h at room temperature. The solution was then passed through a whatmann filter paper (No. 42) and amount of drug dissolved was analyzed spectrophotometrically.
