Aqueous N,N-diethylnicotinamide (DENA) solution as a medium for accelerated release study of paclitaxel

N,N-Diethylnicotinamide (DENA) was identified as an excellent hydrotropic agent for paclitaxel (PTX) in our previous studies. The aqueous solubility of PTX was increased by several orders of magnitude in the presence of DENA. Because of such a high hydrotropic property, DENA was used as a release medium providing a sink condition for the release of PTX from poly(lactic-co-glycolic acid) (PLGA) matrices. The release profiles of PTX from PLGA matrices into DENA, serum and phosphate-buffered saline (PBS) were compared. The stability of PTX in DENA and the degradation of PLGA molecules in DENA were examined. The degradation rate constant of PTX in 2 M DENA was similar to those in other aqueous solutions. The use of 2 M DENA as a release medium allowed differentiation of the release profiles of PTX from PLGA matrices made of different PLGA compositions. The PTX release from PLGA matrices was much faster in DENA solution than in serum or PBS, and the concentration of DENA affected the PTX release rate. The presence of DENA in the release medium increased the hydrolysis rate of PLGA polymers. The faster release of PTX from PLGA matrices in DENA solution may be due to the high PTX solubility and faster degradation of PLGA polymers in the presence of DENA. Our study suggests that the aqueous DENA solution can be used for the accelerated release study of PTX from PLGA matrices.