Pentavalent antimony

In 1912, however, (201) it was discovered that espundia (American mucocutaneous leishmaniasis) can be cured by tartar emetic. It was soon learned that kala-a2ar (visceral leishmaniasis) and oriental sore (a cutaneous form of the disease occurring in the Middle East) also respond to antimonial therapy, especially when compounds of pentavalent antimony are employed. Treatment of leishmaniasis with the latter type of antimonials is safe and effective in over 90% of the cases (202). In 1918, it was demonstrated that tartar emetic is of value in the treatment of schistosomiasis (203). Pentavalent antimonials proved to be less effective. The introduction of antimony compounds for the treatment of parasitic diseases is undoubtedly one of the important milestones in the history of therapeutics (see Antiparasitic agents). 

Meglumine [6284-40-8] antimonate [133-51 -7] C H NO HO Sb, (Glucantime) is a pentavalent antimonial used for the treatment of leishmania sis in Latin America (207) and in the French-speaking areas of Europe and Africa (206). It is adrxiinistered by deep intramuscular injection. Although relatively safe and usually well tolerated, numerous side effects have been observed. It is not available in the United States. 

Antimony compounds have been used to treat leishmaniasis ever since tartar emetic (antimony potassium tartrate) was discovered early in the 20th century to have efficacy against the mucocutaneous form of the disease. The cutaneous form has been treated with tartar emetic formulated in an ointment. Many side effects have been seen with this trivalent antimonial, some of which can be ascribed to the difficulty of obtaining pure antimony for its manufacture. These side effects include toxicity to the heart, Hver, and kidneys. Other promising trivalent antimonials have been abandoned in favor of pentavalent antimonials with lower toxicity. 

Pentavalent antimonial drugs have been the cornerstone of antileishmanial therapy for more than 70 years, in spite of their general toxicity causing a wide range of side effects [2]. Pentavalent antimonial drugs have to be administered parenterally, which is a painful procedure. Meanwhile, resistance is widespread. In India,... 

Zhou Y, N Messier, M Ouellette, BP Rosen, R Mukhopadhyay (2004) Leishmania major LmACR2 is a pentavalent antimony reductase that confers sensitivity to the drug Pentostam. J Biol Chem 279 37445-37451. 

Pentavalent antimony compounds, 20 56 Pentavalent plutonium cations, 19 692 Pentavalent tungsten, 25 386 Pentavalent vanadium aqueous, 25 533... 

Amphotericin B, a polyene, is discussed more fully in Chapter 52. It has produced healing of the mucocutaneous lesions of American leishmaniasis, but its potential for nephrotoxicity makes it a drug of second choice. On the other hand, liposomal amphotericin B, approved by the U. S. Food and Drug Administration (FDA) for treatment of visceral leishmaniasis, is considered the drug of choice for that indication and is much less toxic than pentavalent antimonials or amphotericin B. 

Pentamidine is active against Pneumocystis carinii, trypanosomes, and leishmaniasis unresponsive to pentavalent antimonials. It is an alternative agent for the treatment of P. carinii pneumonia. Although it is more toxic than trimethoprim-sulfamethoxazole, it has been widely used in patients with acquired immunodeficiency syndrome (AIDS), in whom P. carinii infection is common. 

Antimonials are irritating to the intestinal mucosa and therefore are administered by intramuscular or slow intravenous injection. Peak blood concentrations occur in 2 hours. These drugs bind to cells, including erythrocytes, and are found in high concentrations in the liver and spleen. As compared with the trivalent antimonials, which are no longer used, the pentavalent antimonials bind to tissue less strongly. This results in higher blood levels, more rapid excretion, and lowered toxicity. Pentavalent antimonials are rapidly excreted in the urine, with up to one-half of the administered dose excreted in 24 hours. 

No pentavalent antimonial is licensed for use, but sodium stibogluconate is available from the Parasitic Disease Drug Service of the Centers for Disease Control (CDC) for treatment of leishmaniasis. While the pentavalent antimony compounds can be given intravenously or intramuscularly, local infiltration of the lesion in cutaneous leishmaniasis is highly effective. Because of the lower toxicity of liposomal amphotericin B, this drug is considered a first-line choice for vis-cerotropic leishmaniasis rather than the antimonials. 

A. Liposomal amphotericin B was approved by the US. Food and Drug Administration to treat visceral leishmaniasis. Pentavalent antimony compounds, pentamidine, amphotericin B, and aminosi-dine (paromomycin) have all been demonstrated efficacious here. The liposomal amphotericin appears to be better taken up by the reticuloendothelial system, where the parasite resides, and partitions less in the kidney, where amphotericin B traditionally manifests its toxicity. In addition to being better tolerated by patients, it has proved to be very effective in India, where resistance to antimony drugs is widespread. This patient appears to have acquired his infection there, where many infected patients develop darkening of the skin, hence the name kala-azar, or black sickness. Albendazole, an anthelmintic, has no role here. Atovaquone, a naphthoquinone, is used to treat malaria, babesiosis, and pneumocystosis. Pyrimethamine-sulfadoxine is used to treat malaria and toxoplasmosis. Proguanil inhibits the dihydrofolate reductase of malaria parasites and is used in combination with atovaquone. 

Trivalent antimonials (8.93) and pentavalent antimonials (8.94) are sometimes used as antiparasitic agents against leishmaniasis and schistosomiasis. Although the mechanism... 

It is pentavalent antimonial. It inhibits -SH dependent enzymes and block glycolytic fatty acid oxidation pathways. It is rapidly absorbed after IM injection and excreted unchanged in urine. Used in cutaneous and visceral leishmaniasis. It is given parenterally (20 mg/kg/day IM/IV) for three weeks in cutaneous leishmaniasis and for four weeks in visceral and mucocutaneous disease. 

SWARTS REACTION. Fluorination of organic polyhalides with antimony trifluoride (or zinc and mercury fluorides) in the presence of a trace of a pentavalent antimony salt. 

The pentavalent antimony ion in an octahedral environment was postulated as necessary for the partial oxidation of propylene, and the uranium ion was indicated to be important in stabilizing the Sb5+ structurally and in aiding its regeneration with gaseous oxygen during the course of catalytic operation. 

From these experiments it is clear that, in the reaction of a poly-chloroparaffin with antimony trifluoride activated by a pentavalent antimony salt ... 

Mild acidification of molybdate-phosphate solutions yielded the colorless [P2Mos023]"6 anion, isolated as the sodium salt48,49 The heteropoly acid containing pentavalent antimony, H3[SbMo12O40] 48 H20, was reported to have been prepared by refluxing M/20 molybdic acid with M/75 potassium pyroantimonates°), however, more work is necessary to elucidate to exact nature of molybdenum heteropoly compounds containing antimony. 

The electrodeposition of antimony [77] and indium-antimony [78] alloys has been reported in a basic EMICI-EMIBF4 ionic liquid. Antimony trichloride, SbCl3, dissolves in the ionic liquid and forms SbQ, the same as in the basic chloro-aluminate ionic liquid. Metallic Sb can be obtained by the cathodic reduction of SbCl4, as shown in Eq. (9.14). The formal potential of Sb(III)/Sb is reported as —0.27 V vs. AI/Al(in) in the ionic liquid containing Cl at 0.11 M. In addition the oxidation of SbCl4 leads to the formation of a pentavalent antimony species, SbClg ... 

Antimony(lll) fluoride, " antiinony(lll) fluoride activated with pentavalent antimony salts [anlimony(V) fluoride, antimony(V) chloride, antimony(V) bromide, or by the addition of bromine or chlorine to form pentavalent antimony salts in situ], SbFjX, and antimony(V) fluoride substitute active halogens. In general, antimony fluorides can substitute halogens in polyhalogenated compounds when more than one possible site of fluori-natioii is present, the following order of reactivity is observed (where X = Br or C ) ... 

This demonstration marked the beginnings of the CFC industry as we know it today. Continuous processes were developed wherein a chlorocar-bon and HF were fed to a reactor containing antimony pentahalide, usually dissolved in the fluorinated reaction intermediates. Under reaction conditions, pentavalent antimony is somewhat unstable, reverting back to the trivalent state and chlorine. Industry practice is to feed chlorine to oxidize trivalent antimony back to the pentavalent state. In its simplest form the exchange reaction with CCI4 can be written as shown in Eqs. (4) and (5). Over the years, several improvements to such processes have been made... 

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