Therapeutic effect of zinc-containing calcium phosphate suspension injection in thermal burn-rats

The aim of this study was to evaluate the efficacy of suspensions of zinc-containing tricalcium phosphate (TCP) in the healing of thermal burns in rats. β-ZnTCP containing 10 mol % zinc, α-ZnTCP containing 0.9 mol % zinc, and ZnSO4 ·(H2O)7 (ZnSO4) were used. The injections were prepared to suspend ZnSO4 , α-ZnTCP, and β-ZnTCP powders in 2 mL of 1% sodium alginate saline solution containing 2 mg of Zn. In vitro Zn release rates were measured in simulated body fluid. The release of Zn from ZnSO4 was very fast, but that from α-ZnTCP and β-ZnTCP was slowed by transformation to hydroxyapatite. The suspensions were injected into group C (control), D1 (ZnSO4), D2 (α-ZnTCP), and D3 (β-ZnTCP) rats after thermal burns treatment for 3 h. The area under the curve for the plasma Zn for group D1 was the highest, and the order was groups D1 > D2 ≥ D3 ≥ C. The wounded area (Aw) of group D1 had almost the same profile as that of group C, and the Aw at 18 days was about 20%. In contrast, the Aw of group D2 and D3 decreased, and on day 15 was 8% and 37%, respectively. The results indicated that the healing process was shorter in the rats given α-ZnTCP and β-ZnTCP than those given ZnSO4 or the control.