Methemoglobin inducers

METHEMOGLOBIN INDUCERS Methemoglobin in blood During or end of shift 1.5% of haemoglobin B, Ns,... 

The frequently cited sources of biomarker reference values include ACGIH (2005), the Deutsche Forschungsgemeinschaft (DFG) (DFG 2004), and Lauwerys and Hoet (2001). In the ACGIH sourcebook on TLVs and BEIs (ACGIH 2005), BEIs were proposed for 42 substances or groups of substances (such as methemoglobin inducers). Because a number of the substances have more than one determinant (biomarker), a total of 71 determinants were reported. 

Methemoglobin inducers Methemogiobin in blood Methyl chloroform... 

Patients who are critical and do not satisfactorily respond to supportive therapy should be administered specific cyanide antidotes as outlined in Table 19.5. Cyanide antidotes have been classified into three main groups based on their mechanism of action (1) methemoglobin inducers, (2) sulfur donors, and (3) cobalt compounds. The definitive treatment of cyanide poisoning differs in various countries due to different medical practices and guidelines. The safety... 

Specific antidotal therapy Amyl nitrite Methemoglobin inducers Converts hemoglobin to... 

After the initial therapy of methemoglobin inducers, the cyanide has to be converted to thiocyanate which is eliminated in urine. This enzymatic detoxification of cyanide is facilitated by a sulfur donor like sodium thiosulfate. The mechanism of this reaction was discussed earlier under elimination of cyanide. High tissue oxygen markedly potentiates the effects of this reaction. In cases where methemoglobin formation is not desirable, sodium thiosulfate together with oxygen alone is sufficient. The utility of... 

The basic aim of rapid detoxification of cyanide is prevention or reversal of inhibition of cytochrome oxidase by cyanide. This is usually facilitated by providing a large pool of ferric iron in the form of methemoglobin to complex cyanide. Cyanide preferentially competes with the Fe + of methemoglobin as compared with that of cytochrome oxidase and eventually binds with the former to form cyanmethemoglobin. Thereby, the activity of inhibited cytochrome oxidase is restored (Baskin et al., 1992). The various methemoglobin inducers used as cyanide antidotes are discussed. 

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