Effects of penicillamine and dimercaprol on turnover of copper in patients with Wilson's disease

The Role of Zinc in the Treatment of Wilson’s Disease

Wilson’s disease (WD) is a hereditary disorder of copper metabolism, producing abnormally high levels of non-ceruloplasmin-bound copper, the determinant of the pathogenic process causing brain and hepatic damage and dysfunction. Although the disease is invariably fatal without medication, it is treatable and many of its adverse effects are reversible. Diagnosis is difficult due to the large range and severity of symptoms. A high index of suspicion is required as patients may have only a few of the many possible biomarkers. The genetic prevalence of ATP7B variants indicates higher rates in the population than are currently diagnosed. Treatments have evolved from chelators that reduce stored copper to zinc, which reduces the toxic levels of circulating non-ceruloplasmin-bound copper. Zinc induces intestinal metallothionein, which blocks copper absorption and increases excretion in the stools, resulting in an improvement in symptoms. Two meta-analyses and several large retrospective studies indicate that zinc is equally effective as chelators for the treatment of WD, with the advantages of a very low level of toxicity and only the minor side effect of gastric disturbance. Zinc is recommended as a first-line treatment for neurological presentations and is gaining acceptance for hepatic presentations. It is universally recommended for lifelong maintenance therapy and for presymptomatic WD.

Stability of the Hsp90 inhibitor 17AAG hydroquinone and prevention of metal-catalyzed oxidation

17-(allylamino)-17-demethoxygeldanamycin (17AAG) is a benzoquinone ansamycin Hsp90 inhibitor which has promising anticancer activity in vitro, in animal models and in clinical trials. 17AAG has poor water-solubility which is a potential problem for clinical formulation. The hydroquinone derivative of 17AAG, 17AAG hydroquinone (17AAGH(2)), is considerably more water soluble and since we previously demonstrated that 17AAGH(2) was a more potent Hsp90 inhibitor than its parent quinone, it is a good candidate for clinical use and is currently in clinical trials. However, 17AAGH(2) can be oxidized back to 17AAG under aerobic conditions so we tested the relative stability of 17AAGH(2) and the effect of different metal ions and metal chelators on the oxidation of 17AAGH(2). We found that copper could accelerate 17AAGH(2) oxidation while copper chelators such as D-penicillamine could inhibit oxidation. Human serum albumin (HA) has copper-binding ability and we found that HA diminished the rate of 17AAGH(2) oxidation. Although we found that 17AAG could associate with HA, no association was observed between 17AAGH(2) and HA. In summary, our data demonstrates that copper chelators can prevent 17AAGH(2) oxidation and suggests that HA prevents 17AAGH(2) oxidation via a copper chelation mechanism. Agents that prevent oxidation may be useful in clinical formulations of 17AAGH(2.)

The metabolism of 35S-D-penicillamine in man

1. The excretion and metabolism of 35S-D-penicillamine (200 mg orally) was studied in four healthy male volunteers. 2. The major route of excretion was the urine with 82% of the administered dose being voided over three days (73% during the first 24 h); the remainder was excreted in the faeces. 3. Metabolism occurred via the pathways of S-methylation, N-acetylation and disulphide formation. Extensive degradation of the molecule was observed with the production of large amounts of inorganic sulphate.

D-penicillamine therapy of acute arsenic poisoning

Severe poisoning resulting from single ingestions of rodenticides, herbicides, or insecticides containing arsenic have been frequently recognized. We record three cases of solubilized arsenic trioxide poisoning in Navajo Indian children and one case of sodium arsenate ingestion in an infant. One fatality occurred during dimercaprol therapy prior to initiation of therapy with D-penicillamine. Three survivors were treated with 2.3-dimercaprol intramuscularly and with oral D-penicillamine. The use of D-penicillamine in arsenic poisoning has not been generally appreciated. Excretion data from the three children are presented which document the effectiveness of D-penicillamine, administered orally in four daily doses of 25 mg/kg/dose, in the therapy of arsenic intoxication. Excretion data for the trace metals, zinc and copper, during D-penicillamine chelation therapy are also reported.

Wilson's disease

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