Compatibility study between ferulic acid and excipients used in cosmetic formulations by TG/DTG, DSC and FTIR

Ferulic acid (4-hydroxy-3-methoxycinnamic acid) is a phytochemical constituent from the polyphenols group commonly found in whole grains, spinach, parsley, grapes and rhubarb. It has been widely applied in skin care formulations as photoprotective agent and delayer of cutaneous photoaging processes. This work aims to establish a protocol to the development of cosmetic formulations using thermoanalytical techniques (TG/DTG and DSC) and Pearson's correlation by FTIR data, in order to evaluate the compatibility between ferulic acid and excipients used in skin care formulations. The results obtained from the thermoanalytical techniques indicated compatibility between ferulic acid and the following excipients: passion fruit seed oil, Carbopol(A (R)) Ultrez 30, EDTA, Crodabase CR2(A (R)), Crodamol (TM) GTCC and Dow Corning(A (R)) RM 2051. Nevertheless, the analysis also demonstrated the possibility of some interaction between ferulic acid and the following excipients: glyceryl stearate, Rapithix(A (R)) A-60 and Optiphen(A (R)). To validate these results, it was demonstrated by Pearson's correlation that passion fruit seed oil, Carbopol(A (R)) Ultrez 30, EDTA, Crodabase CR2(A (R)), Crodamol (TM) GTCC, Dow Corning(A (R)) RM 2051, glyceryl stearate and Rapithix(A (R)) A-60 do not have any incompatibility that may compromise ferulic acid properties. Finally, it was also proved a meaningful incompatibility between ferulic acid and Optiphen(A (R)) using Pearson's correlation. Thus, it is not recommended to use Optiphen(A (R)) in the development of cosmetic formulations to carry ferulic acid.