The Effect of Humidity on the Dissolution Kinetics and Tablet Properties of Immediate-Release Tablet Formulation Containing Lamotrigine

This study aims to find the effects of high (75%) and low (30%) humidity conditions and its correlation with formulation composition on dissolution kinetics of lamotrigine (LMT) from prepared immediate-release tablets during one- and four-week periods. Two types of fillers microcrystalline cellulose (MCC) or anhydrous lactose (LAC), disintegrant sodium starch glycolate (NaSG, 0.5% or 4%), and lubricant magnesium stearate (MgST, 0.25% or 5%) were used. A three-factor two-stage complete factorial design (2(3)) was used to assess the influence of the composition of the tested formulations. The tablets were produced by direct compression and characterized using a disintegration test, a resistance to crushing test, and dissolution tests (pH 1.2 and pH 6.8). Using Design Expert software, it was concluded that in addition to the effect of fillers on pH 6.8, NaSG has a significant impact after exposure to high and low humidity, as well as its interaction with LAC and MCC. In the dissolution medium pH 1.2, under conditions of high humidity, the content of MgST and NaSG and their interaction show a significant influence. The release rate of LMT was affected by humidity as well as type of excipients and their interactions.