Dimercaprol toxicity

BAL British Anti-Lewisite. Dimercaprol, a treatment for toxic inhalations. 

Simultaneous administration of gold compounds with other nephrotoxic, hep-atotoxic, or myelosuppressive and penicillamine drugs must be avoided because of associated toxicities. Metal toxicity can be treated with dimercaprol, and drugs must be withdrawn. 

One of the chemical derivatives of dimercaprol (BAL) is DMSA. DMSA is an orally active chelating agent, much less toxic than BAL, and its therapeutic index is about 30 times higher (Angle and Kuntzelman, 1989). The empirical formula of DMSA is C4H6O4S2 and its molecular weight is 182.21. It is a weak acid soluble in water. 

Dimercaprol (British Anti-Lewisite, BAL). Arsenic and other metal ions are toxic in low concentration because they combine with the SH groups of essential enzymes, thus inactivating them. Dimercaprol provides SH groups which combine with the metal ions to form relatively harmless ring compounds which are excreted, mainly in the urine. As dimercaprol, itself, is oxidised in the body and renally excreted, repeated administration is necessary to ensure that an excess is available imtil all the metal has been eliminated. 

The pharmacological tools to detoxify arsenicals are sulphydryl reagents. The classic drug for that purpose is 2,3-dimercapto-l-propanol, dimercaprol (British antilewisite, BAL). Since this compound has side effects and a low safety ratio, new analogs with less adverse effects have been developed, e.g. dimercaptopropanesulphonate, dimercaptosuc-cinic acid and dithioerythritol . The efficiency and toxicity of these agents need to be further evaluated. 

Dimercaptopropane sulfonate (2,3-dimercapto-l-propane-sulfonate) is a water-soluble and possibly less toxic derivative of dimercaprol, used in poisoning with arsenic, bismuth, mercury, and other heavy metals. 

Succimer is the meso isomer of 2,3-dimethylmercapto-succinic acid (DMSA). It is used as a lead chelator for oral administration (1). Nausea, vomiting, diarrhea, and anorexia are common. Rashes, sometimes necessitating withdrawal, have been reported in up to 10% of adults and 5% of children, and mild transient rises in serum transaminase activity in 6-10% (mostly adults) (2,3). Life-threatening hyperthermia occurred on two occasions in one subject, but no details were given. Iron can be safely and effectively given to patients taking succimer, which (unlike dimercaprol) does not appear to deplete iron stores or to form a toxic chelate that would preclude the parenteral administration of iron (3). 

Dimercaprol is a synthetic therapeutic substance developed during World War II as an antidote against the vesicant arsenic war gases (lewisite). The first experiments were based on the fact that arsenic products react with SH radicals. Among all the compounds originally tested, BAL was the most effective and the least toxic. In 1951, BAL was used by a... 

If the BAL-metal complex is oxidized, the metal is released and can exert its toxic effect again therefore, the dosage of dimercaprol must be high enough to ensure the excess of free BAL in body fluids until the metal is completely excreted. 

If toxicity occurs, further exposure to gold or gold salts should be prevented. Dimercaprol may be used... 

British antilewisite (BAL) or dimercaprol was developed as an antidote for lewisite. It is used in medicine as a chelating agent for heavy metals. Although BAL can cause toxicity itself, evidence suggests that BAL in oil administered intramuscularly will reduce the systemic effects of lewisite. BAL skin and ophthalmic ointment decrease the severity of skin and eye lesions when applied immediately after early decontamination, but neither of these ointments is currently manufactured. 

British Anti-Lewisite (BAL), also known as Dimercaprol, is a chelating agent than can reduce systemic effects from Lewisite. BAL works by binding the arsenic group in Lewisite and displacing it from tissue binding sites. If applied topically within minutes, after decontamination, BAL may prevent or reduce the severity of cutaneous and ocular toxicity (8). 

In comparison to the majority of odier heavy metals, tungsten and most of its compounds possess very low toxicity, if at all. Intoxications occur rarely, almost exclusively by occupational exposure. As treatment in acute poisoning, Dimercaprol (British Antilewisite) may be useful. 

The heavy-metal chelating properties of thiols were taken advantage of in the design of dimercaprol ( British Anti-Lewisite, BAL) as counter poison of the arsenical war gas lewisite (Figure 20.43). Today dimercaprol is used to treat poisoning by compounds of gold, mercury, antimony and arsenic. The toxic nature of the heavy metals is masked and chelate is stable enough to be excreted as such in the urine. 

Enhanced excretion of vanadium was achieved with chelation therapy provided by deferoxamine mesylate (DFOA) (Gomez et al. 1988). Humans or animals with vanadium poisoning have not been helped by the chelating agent dimercaprol (BAL), which is often effective in lessening the toxicity of other metals (Lusky et al. 1949). Intraperitoneal injections of ascorbic acid and of ethylene diamine tetraacetate (EDTA) reduced vanadium-induced morbidity in mice and rats (Jones and Basinger 1983 Mitchell and Floyd 1954). 

Dimercaprol (BAL) Arsenic, gold, mercury, lead oral succimer for milder lead and mercury toxicity... 

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