Nomogram for Computing the Value of Similarity Factor

The objective of present work was to construct nomogram for obtaining a value of similarity factor (f(2)) by employing the values of number of observations (n) and sum of squared difference of percentage drug dissolved between reference (R) and test (T) products [Image: see text]. The steps for rearrangement of equation of similarity factor are presented. The values of f(2) were selected in the range of 45 to 100 for 4 to 12 observations (n) for computing the values [Image: see text] of Linear regression analysis was performed between number of observations and [Image: see text]. Perfect correlation was observed in each case. Nomogram was constructed and later it was validated by using drug dissolution data from literature and our laboratory. The use of nomogram is recommended during research and development work to investigate effect of formulation or process variables. The nomogram can also be used during change in manufacturing site or change in equipment. It is concluded that the steps for calculation of f(2) can be truncated in the middle (i.e. at the step of calculation of factor [Image: see text] and a decision of similarity/dissimilarity can be taken employing the nomogram.