Zinc Maintenance Therapy for Wilson Disease: A Comparison Between Zinc Acetate and Alternative Zinc Preparations

Abstract

We evaluate Wilson disease (WD) treatment with zinc acetate (U.S. Food and Drug Administration approved) and alternative zinc salts. Studies examining zinc therapy in WD are few, and data on alternative zinc salts are limited. We describe one of the largest recent studies of zinc therapy in WD. First, we conducted a single-center retrospective review of 59 patients with WD (age 6-88 years, 32 female patients) treated with zinc (50-150 mg) for 0.8 to 52 years (median, 26 years); most were on prior chelation therapy (n = 39). Second, we developed a survey to explore patients' zinc therapy experience. Primary endpoints were alamine aminotransferase (ALT) and urine copper excretion (µg/24 hours). Urine copper was categorized as low <25 μg (possible overtreatment), target 25-100 μg, or elevated >100 μg (possible noncompliance or treatment failure). The target range was reached in 81% of patients on zinc acetate, 73% on zinc gluconate, and 57% on alternative zinc. Low urine copper was not associated with a high ALT. ALT was normal in 77% of patients with target urine copper but only in 16% with urine copper >100 µg. ALT elevations were not significantly different between zinc salts (Kruskal-Wallis, P = 0.26). Our survey demonstrated the mean age of starting zinc was 26.8 years (3.5-65 years); most were treated with zinc acetate (45%) and zinc gluconate (42%). Before zinc treatment, 45% of patients were symptomatic; the majority of patients (80%) were asymptomatic on zinc. Gastrointestinal side effects were the predominant reason for changing zinc salts (38%), but most reported no side effects on current zinc therapy (67%). Conclusion: Effective treatment with zinc is possible in many patients with WD. The potential for treatment failure suggests close monitoring and consideration of alternative treatments are paramount for those without both a normal serum ALT and appropriate urine copper excretion.