General Information

Galzin (Zinc Acetate) as the dihydrate is a salt of zinc used to inhibit the absorption of copper in patients with Wilson's disease.

Galzin is specifically indicated for maintenance treatment of patients with Wilson’s disease who have been initially treated with a chelating agent.

Galzin is supplied as a capsule for oral administration. The recommended adult dose is 50 mg as zinc three times daily.

Mechanism of Action

Galzin (Zinc Acetate) as the dihydrate is a salt of zinc used to inhibit the absorption of copper in patients with Wilson's disease. Introduction Wilson's disease (hepatolenticular degeneration) is an autosomal recessive metabolic defect in hepatic excretion of copper in the bile, resulting in accumulation of excess copper in the liver, and subsequently in other organs, including the brain, kidneys, eyes, bone, and muscles. In this disease, hepatocytes store excess copper, but when their capacity is exceeded copper is released into the blood and is taken up in extrahepatic sites, such as the brain, resulting in motor disorders (ataxia, tremors, speech difficulties) and psychiatric manifestations (irritability, depression, deterioration of work performance). Redistribution of excess copper in hepatocytes leads to hepatocellular injury, inflammation, necrosis, and eventual cirrhosis. Patients may present clinically with predominantly hepatic, neurologic, or psychiatric symptoms. The disease has been treated by restricting copper in the diet, and the use of chelating agents to bind free copper to reduce its toxicity and facilitate its excretion. The purpose of initial treatment of symptomatic patients with a chelating agent is to detoxify copper. Once the patient's symptoms have stabilized clinically, maintenance treatment begins.

Clinical Trial Results

In the single center United States trial, 60 patients with Wilson’s disease (31 male, 29 female) who had adequate detoxification of copper after initial chelation therapy were entered into a copper balance study of various dose regimens of zinc acetate. Patients were hospitalized to carefully control food and liquid intake. Food, urine and feces were analyzed for copper content, and copper balance was defi ned as the difference between copper intake and copper elimination/excretion over a 10-day period. A patient was considered in adequate copper balance if the result was less than +0.25 mg copper/day. While all zinc acetate regimens appeared better than no therapy, there was little experience with doses other than 50 mg t.i.d. Once daily dosing did not appear to give satisfactory control in many cases, and would be inadequate in patients with poor compliance. Based on the limited data available 25 mg t.i.d. was also thought to be an adequate dose regimen, and not shown to be inferior to 50 mg t.i.d. Dose related toxicity was not found in this study.

Symptomatic Patients Initially Treated With a Chelating Drug

Clinical parameters such as neuropsychiatric status including evaluation of speech, and liver function tests were followed as the patients continued therapy on an adequate zinc acetate dose regimen. One hundred and thirty-three patients were followed for up to 14 years. There was no deterioration of neuropsychiatric function including speech and biochemical liver function tests, including bilirubin, transaminases, alkaline phosphatase and lactic dehydrogenase. The liver function tests remained either within normal range or slightly above the upper limit of normal for up to 9 years of treatment.

Pre-symptomatic Patients

In this study 30 pre-symptomatic patients were followed for up to 10 years. Diagnosis of the pre-symptomatic Wilson’s disease was made on the basis of a liver copper value greater than 200 μg of copper per gram dry weight of tissue. Non-ceruloplasmin copper levels, 64Cu balance studies, and clinical parameters were assessed. No patient developed symptoms of Wilson’s disease in this cohort. Since the cloning and sequencing of the abnormal genes in Wilson’s disease patients, many mutations have been identified that may affect the rate of disease progression. No matched historical control has been compared to this experience, nor has another center replicated this experience. In a study in the Netherlands, using zinc sulfate, 27 patients were followed up to 29 years by mainly clinical parameters such as tremors, dysarthria, dystonia, ataxia and Kayser-Fleischer rings. No deterioration of the clinical status was observed. In some cases, Kayser-Fleischer rings disappeared and clinical signs and symptoms improved.