Film-coated zinc sulphate tablets and the effect of humidity on tablet properties.

Preparation of film-coated zinc sulphate tablets and the effect of relative humidity and aging on the physical properties of these coated tablets were investigated in this study. Shellac; Eudragit E and L, hydroxypropyl methylcellulose (HPMC) and HPMC-Eudragit E mixture were used as film-forming materials. As zinc sulphate has efflorescent properties, the effect of humidity on the coated tablets was studied and physical stability tests were carried out. Coated tablets were kept in bottles and in open petri-dishes at different relative humidities (30, 55 and 85%) at room temperature over 12 weeks, and the weight loss, hardness, and disintegration times of these tablets were followed. Findings indicated that film-coated zinc sulphate tablets having good tablet quality can be prepared using the formulations (F-VI) HPMC-Eudragit E mixture and (F-III) Eudragit E as coating materials. Thus, the effect of relative humidity on tablet properties can be reduced.