Unithiol

Mechanism of 2,3,7,8-TCDD was not established so far means of specific therapy as to this compound poisoning are not available. Experiments with animals have shown that activated carbon, zeolite (subject to introduction of sorbents immediately after poison), unithiol, Liv-52, carsil, festal, guaranteed survival of 20-50% laboratory rats [6],... 

Management of chronic arsenic poisoning consists primarily of termination of exposure and nonspecific supportive care. Although empiric short-term oral chelation with unithiol or succimer for symptomatic individuals with elevated urine arsenic concentrations may be considered, it has no proven benefit beyond removal from exposure alone. Preliminary studies suggest that dietary supplementation of folate—thought to be a cofactor in arsenic methylation—might be of value in arsenic-exposed individuals, particularly men, who are also deficient in folate. 

In addition to intensive supportive care, prompt chelation with oral or intravenous unithiol, intramuscular dimercaprol, or oral succimer may be of value in diminishing nephrotoxicity after acute exposure to inorganic mercury salts. Vigorous hydration may help to maintain urine output, but if acute renal failure ensues, days to weeks of hemodialysis or hemodiafiltration in conjunction with chelation may be necessary. Because the efficacy of chelation declines with time since exposure, treatment should not be delayed until the onset of oliguria or other major systemic effects. 

Unithiol and succimer increase urine mercury excretion following acute or chronic elemental mercury inhalation, but the impact of such treatment on clinical outcome is unknown. Dimercaprol has been shown to redistribute mercury to the central nervous system from other tissue sites, and since the brain is a key target organ, dimercaprol should not be used in treatment of exposure to elemental or organic mercury. Limited data suggest that succimer, unithiol, and N- acetyl-L-cysteine (NAC) may enhance body clearance of methylmercury. 

Chemical structures of several chelators. Ferroxamine (ferrioxamine) without the chelated iron is deferoxamine. It is represented here to show the functional groups the iron is actually held in a caged system. The structures of the in vivo metal-chelator complexes for dimercaprol, succimer, penicillamine, and unithiol (see text) are not known and may involve the formation of mixed disulfides with amino acids. 

When used in therapeutic doses, dimercaprol is associated with a high incidence of adverse effects, including hypertension, tachycardia, nausea, vomiting, lacrimation, salivation, fever (particularly in children), and pain at the injection site. Its use has also been associated with thrombocytopenia and increased prothrombin time—factors that may limit intramuscular injection because of the risk of hematoma formation at the injection site. Despite its protective effects in acutely intoxicated animals, dimercaprol may redistribute arsenic and mercury to the central nervous system, and it is not advocated for treatment of chronic poisoning. Water-soluble analogs of dimercaprol—unithiol and succimer—have higher therapeutic indices and have replaced dimercaprol in many settings. 

Unithiol has been reported to have a low overall incidence of adverse effects (< 4%). Self-limited dermatologic reactions (drug exanthems or urticaria) are the most commonly reported adverse effects, although isolated cases of major allergic reactions, including erythema multiforme and Stevens-Johnson syndrome, have been reported. Because rapid intravenous infusion may cause vasodilation and hypotension, unithiol should be infused slowly over an interval of 15-20 minutes. 

Cd Citrate, tartrate, I-. CN-, SCN-, S2O32-, unithiol, thioglycollic acid, DHG, NTA, EDTA... 

Zn Citrate, tartrate, OH-, glycols, CN-, NH3, tren, penten, SCN-, thioglycollic acid, unithiol, BAL, DHG,... 

Abbreviations DHG = Ar,Ar-di(2-hydroxyethyl)glycine NTA = nitrilotriacetic acid EDTA = ethylenediaminetetraacetic acid tiron = pyrocatechol-3,5-disulfonic acid BAL = 2,3-dimercaptopropanol unithiol = sodium 2,3-dimercaptopropane sulfonate tren — triaminatriethylamine penten = tetrakis(aminoethyl)ethylenediamine bipy = 2,2 -bipyridyl phen = 1,10-phenanthroline. 

Details of masking by potassium cyanide, triethanolamine, thioglycollic acid, mercaptopropionic acid, BAL, unithiol, dimercaptosuccinic acid, NHaF, H202, KOH, K2SC>4, KI, Na2S203, thiourea, thiosemicarbazide, phen, acac and demasking reactions are given by Pribil.87... 

BAL is lipid soluble and it has the ability to remove metal deposits not available to attack by other chelators. More effective and less toxic compounds have since become available these include vicinal dithiols, other dithiols, aminocarboxylic acids, cysteine derivatives, and others. Unithiol (sodium 2,3-dimercaptopropane-l-sulfonate DMPS) forms very stable, water soluble complexes with Hg2+, Pb2+, Cd2+, Zn2+, Bi3+, As3+, Sb2+ and Ni2+. The complexes are nearly all less toxic than... 

Unithiol has no FDA-approved indications, but experimental studies and its pharmacologic and pharmacodynamic profile suggest that intravenous unithiol offers advantages over intramuscular dimercaprol or oral succimer in the initial treatment of severe acute poisoning by inorganic mercury or arsenic. Aqueous preparations of unithiol (usually 50 mg/mL in sterile water) can be administered at a dose of 3-5 mg/kg every 4 hours by slow intravenous infusion over 20 minutes. If a few days of treatment are accompanied by stabilization of the patient s cardiovascular and gastrointestinal status, it may be possible to change to oral administration at a dose of 4-8 mg/kg every 6-8 hours. Oral unithiol may also be considered as an alternative to oral succimer in the treatment of lead intoxication. 

Even if anionic chaotropes are the most popular neoteric IPRs, polarizable cations such as sulfonium and phosphonium reagents showed single selectivity toward polarizable anions their behavior was rationalized on the basis of their chaotropicity. Probe anion retention generally increases in the order of tributylsulfonium < tetrabutylammonium < tetrabutylphosphonium. Interestingly, retention was found to be influenced by the kosmotropic/chaotropic character of both the IPR and the probe anion [93] and this confirms the peculiarities of hydrophobic ion-pairing. Quaternary phosphonium salts provided increased selectivity compared to ammonium in the IPC of heavy metal complexes of unithiol [112]. 

Shapovalova, E.N. et al. Ion-pair chromatography of metal complexes of unithiol in the presence of quaternary phosphonium salts. J. Anal. Chem. 2001, 56, 160-165. 

DMPS was first introduced in the Soviet Union in the 1950s as Unithiol . Its empirical formula is C3H703S3Na and its... 

Unithiol (dimercaptopropanesulphonate, DMPS) effectively chelates lead and mercury it is well tolerated. 

Less toxic and more water-soluble derivatives of BAL have been sought, these include glycoside derivatives, the sulfonate derivative dimercaptopropanesulfonate (DMPS or Unithiol ) and dimercapto-succinic acid (DMSA), which have been used clinically. 

Many other sulphur-organic reagents have found use in the determination of Ru, e.g., rubeanic acid [44] and unithiol [45]. 2-Thiobarbituric acid has been used in a method based on derivative spectrophotometry [46]. Dithizone (at 85 C) forms with Ru a complex extractable into CHCI3 [47]. 

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