Purpose: This study aimed to develop a synchronized and sustained-release silymarin dropping
pill, and to evaluate its pharmacokinetic characteristics.
Method: Polyoxyethylene stearate, glyceryl monostearate, and stearic acid were used to prepare the
dropping pills. X-ray powder diffraction, differential scanning calorimetry, and release were used to
evaluate its physicochemical properties. The plasma concentration of silybin in beagle dogs after oral
administration of silymarin dropping pills and silymarin capsule was determined by RP-HPLC.
Results: Synchronized release was achieved with high similarity factor f2 values between every set of
two of the five components. Mean plasma concentration-time curves of silymarin after oral administration
of dropping pills in beagle dogs were in accordance with first-order absorption and open twocompartment
model. The Tmax, Cmax, and AUC0-∞ of dropping pills in beagle dogs were 0.8750±0.13 h,
0.8183±0.07 μg·ml-1, and 2.274±0.90 μg·h·ml-1, respectively. Silymarin dropping pills prolonged
in vivo exposure and reduced maximum in vivo concentration, achieving a stable level in the serum.
Conclusion: The combination of solid dispersion technique and dropping pill formulation allowed synchronized
release of multiple components in herbal medicine, and has potential application in the
development of sustained release in herbal medicine.