Study on absorption and accumulation of mercury in rats by repeated administration of Yuhong ointment

Abstract

To study in vivo mercury absorption and accumulation through repeated transdermal administration of Yuhong ointment containing calomel, in order to provide scientific evidences for clinical safe medication. A total of 100 SD rats were randomly classified into five groups: the control group, the Yuhong ointment group, the double-concentration Yuhong Ointment group, the quadruple-concentration Yuhong ointment group and the 1.6% calomel group. The rats were treated with the dosage of 0.04 g . cm-2 by repeated transdermal administration for 2, 4 weeks. After the drug discontinuance for 4 weeks, the levels of mercury in blood, urine, and tissues of heart, liver, brain and kidney were determined, respectively. Compared with the control group, the blood mercury level of the Yuhong ointment group show no obvious change after treatment for 4 weeks. However, the levels of mercury in blood and urine of other experimental groups increased significantly with time and the increase in dosage, and so did the level of mercury in major organ. At 4 weeks, all experimental groups showed increase in the content of mercury, and kidneys displayed the highest level, whereas brain displayed the lowest level After the drug discontinuance for 4 weeks, the mercury level in blood and urine of every dose group recovered to normal, with significant decline in the content of mercury in each organ. After transdermal administration in rats for 4 weeks, there was no obvious absorption of mercury in blood. Mercury was mainly accumulated in kidneys and excreted through urine. The results suggest that the patients' mercury content and kidney function indexes need to be monitored in long-term clinical use of Yuhong ointment.