Zinc is now one of the recommended therapies for the long-term management of Wilson's disease. Zinc has shown clinical efficacy at doses of 50 mg three times daily in the stimulation of metallothionein synthesis and reduction of copper absorption. The mean plasma elimination half-lives of most highly water soluble drugs, like zinc sulphate, are relatively short (2-4.5 h), which necessitates several applications a day. Long-acting sustained and controlled release preparations make a once-a-day dose treatment possible, thus improving the patients' compliance. The rate and extent of drug release...