Efficacy of zinc acetate hydrate for hypozincemia in the elderly is influenced by the initial accumulated exposure dose after taking zinc acetate hydrate

This study aimed to determine the efficacy of zinc acetate hydrate (ZAH) for hypozincemia in elderly hospitalized patients with an accumulated exposure of < 1000 mg of ZAH and to explore the factors affecting the therapeutic efficacy of ZAH. Seventy-four patients (mean age, 82 years) were enrolled in this study. All patients (n = 74) had low serum zinc levels (< 80 μg/dL), and the mean serum zinc concentration before ZAH administration was 53.6±10.7 μg/dL. The median serum zinc level (μg/dL) elevated per tablet (25 mg) of ZAH was 1.26 μg/dL, and the patients were divided into two groups, the slightly increased (< 1.26) and significantly increased (≥ 1.26) groups, based on the median cutoff value for the median increase in serum zinc level. A significant difference was found between the slightly increased (0.63±0.35 μg/dL, n = 36) and significantly increased (2.37±0.95 μg/dL, n = 38) groups (p < 0.0001, Wilcoxon rank-sum test). Logistic regression analysis with the accumulated exposure dose of ZAH, sex, and body weight as multivariate variables showed a significant difference in the accumulated exposure dose (total number of tablets per 25 mg: odds ratio, 1.119; 95% confidence interval, 1.052???1.203; p = 0.0009). There was no effect of underlying disease or of diet or zinc-containing intravenous or enteral nutrition on serum zinc levels. These results suggest that at an accumulated exposure of < 1000 mg of ZAH, serum zinc levels tend to increase with smaller accumulated doses. Therefore, serum zinc concentrations should be measured at the accumulated exposure to 500‐1000 mg after ZAH initiation for the treatment of zinc deficiency in elderly hospitalized patients.