[Physicochemical properties and drug release rate of calcium phosphate cement containing Danshen composite injection]

To investigate the physicochemical properties of the calcium phosphate cement (CPC) containing Danshen composite injection and its drug release rate.

This experiment included 4 groups and each group contained 6 specimens. CPC (2 g) was mixed with the setting solution that served as the control group; 0.1, 0.5 and 1.0 ml of Danshen composites injection (concentration, 1 000 mg/ml; pH, 7.35) were respectively added to CPC (2 g), which were used as the experimental groups 1, 2 and 3. The resulting specimens were investigated by the X-ray diffraction (XRD), the fourier transformed infrared spectroscopy (FTIR), and the scanning electron microscope (SEM).

The XRD analysis showed that the control group had a typical diffraction pattern of the hydroxypatite (HAP), which was consistent with the standard pattern of HAP. When more Danshen was added in the experimental groups, the diffraction peaks of HAP gradually decreased; when the diffraction angle 2theta was about 25.92 degrees, the HAP peaks disappeared. Based on the FTIR analysis, with an increase of the drug concentration, the absorption peak of the hydroxy groups decreased. The SEM showed that the size of the CPC particle was related to the drug concentration; with an increase of the drug concentration, the CPC particle increased in number, resulting in an increasing trend of coacervation. The elution test showed that the drug-release rate and capacity varied with the different concentrations of Danshen. The initial release rate was relatively great, but after 96 hours the rate slowed down, lasting for a long time.

The physicochemical properties of CPC do not change when a proper dose (0.1 ml/2 g) of Danshen is added to CPC. The Danshen composite can be effectively released from CPC, and so CPC can be used as an ideal drug-delivery carrier for Danshen composite.