Abstract: 
Curcumin (CU), a yellow pigment obtained from Curcuma longa shows profound biological activities. Literature reveals that CU is insoluble in water and susceptible to higher pH. This work is focused firstly to study the susceptibility of curcumin in water, various pH conditions in presence and absence of ascorbic acid (AA), tartaric acid (TA) and citric acid (CA) by a simple UV absorption method and secondly to prepare and evaluate curcumin solid dispersions (CSD) by physical mixtures, hot melt method and solvent evaporation method using PEG-4000, PEG-6000 and PVP K-30 as carriers. Drug, carrier ratio for physical mixtures and hot melt method was 1:1, 1:4 and 1:8; drug, carrier and adsorbent (micro crystalline cellulose) ratio in solvent evaporation method was 1:1:2. Selected formulations with better solubility were studied for TLC, FTIR, SEM, X-ray diffraction studies, in vitro release and in vitro absorption studies using everted rat gut technique. Results indicated that the CU and CSD were unstable in solution; the stability was more in acidic pH and decrease as the pH increases. Presence of AA, TA and CA in solution enhanced the CU aqueous stability relatively by 3 folds in pH 7.4 however more degradation was observed in CSD solutions in pH 7.4 even in presence of these acids. Hot melts of drug with PEG 6000 in 1:8 ratio showed maximum solubility of 1mg/ml than that of other CSDs. Maximum in vitro release was observed by hot melts than that of other CSDs. Hot melts showed burst release in 10 min followed by the degradation of curcumin in aqueous solution indicating occurrence of rapid hydrolytic reaction. In vitro absorption of hot melts and pure curcumin in rat gut was insignificant as the permeability of both were negligible.

Keywords: Curcumin, Solution, Stability, Solid Dispersions, In-vitro Release.