Penicillamine Iron compounds

Other Iron Compounds of Biological Interest.—The valency of iron in a range of ferredoxin extracts has been determined by ESCA. The structure of the Fe—S complex in a bacterial ferredoxin has been determined. The iron and sulphur atoms occupy alternate corners of a cube and four more sulphur atoms project from the iron atoms.Admission of oxygen to a neutral solution of Fe and excess penicillamine gives a red bis-complex, which is relatively stable in aqueous solution at room temperature. Quantitative... 

Iron compounds reduce the systemic availability of penicillamine to about 35% and copper excretion to about 28%, probably as a result of catalysis of the oxidation of penicillamine to its disulfide (2,398,400). Even the iron present in certain multivitamin formulations can be sufficient to cause interference, and when a patient who has regularly taken iron stops taking it, increased absorption of penicillamine and adverse effects can ensue (401,402). 

Penicillamine is well absorbed (40-70%) from the GI tract and therefore has a decided advantage over many other chelating agents. Food, antacids, and iron reduce its absorption. Peak concentrations in blood are obtained 1—3 hours after administration. Unlike cysteine, its nonmethylated parent compound, penicillamine, is somewhat resistant to attack by cysteine desulfhydrase or L-amino acid oxidase and is relatively stable in vivo. Hepatic biotransformation is responsible for most of the degradation of penicillamine, and very little is excreted unchanged. Metabolites are found in both urine and feces. 

Penicillamine Antacids (containing Ap and/or Mg ), iron compounds, food Formation of less soluble penicillamine chelates resulting in reduced absorption of penicillamine... 

The absorption of penicillamine can be reduced as much as two-thirds by oral iron compounds. 

An established and elinieally important interaetion. For maximal absorption give the iron at least 2 hours after the penicillamine. This should reduce their admixture in the gut. Do not withdraw iron suddenly from patients stabilised on penicillamine because the marked increase in absorption that follows may precipitate penicillamine toxicity. The toxic effects of penicillamine seem to be dependent on the size of the dose and possibly also related to the rate at which the dosage is increased. Only ferrous sulfate and fumarate have been studied but other iron compounds would be expected to interact similarly. 

Penicillamine is known to form complexes of varying stability with several metal ions. In neutral solution, penicillamine complexes with mercury, lead, nickel, and copper are relatively more stable than those of zinc, iron, and manganese. The three functional groups of penicillamine may be engaged in the formation of metal complex, and the resultant compounds may be polymeric in structure. 

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