Contribution of formulation and excipients towards enhanced permeation of curcumin.

Curcumin (CRM) (CAS number 458-37-07), a naturally-occurring molecule, has diverse pharmacological actions. Recently our research group demonstrated that poor permeability also contributes to its poor oral bioavailability. A self nano-emulsifying drug delivery system (CRM SNEDDS) consisting of Labrasol, Gelucire 44/14, Vitamin E TPGS and PEG 400 was designed and provided 16 times improvement in oral bioavailability in rats, at a dose of 250 mg/kg body weight. Caco-2 cell transport studies were conducted for CRM SNEDDS and CRM in the presence of individual excipients, to determine the extent of improvement in permeability. Papp values for CRM, CRM SNEDDS and CRM in combination with 4 individual excipients were calculated. Transepithelial electrical resistance value was assessed to evaluate the cell morphology and the cellular tight junctions. Permeation of a transcellular marker, Lucifer Yellow was used as a marker to assess monolayer integrity. The tested excipient concentrations were found to be non-toxic to the cell monolayer in 2 h incubation. Results showed that the Papp increased 6.35 times for curcumin in CRM SNEDDS as compared to CRM. Individual excipients enhanced permeation from 1.97 to 6.35 times, with Labrasol showing the highest enhancement of 6.35 times.