Trivalent arsenic is metabolized, primarily in the liver, to the non toxic compounds. The major form of arsenic in urine after ingestion of arsenic trioxide is dimethylarsinic acid (50%) indicating in vivo methylation reaction. Other compounds excreted in urine are methylarsonic acid (14%), pentavalent arsenic (8%) and trivalent arsenic (8%). Excretion is by the kidney; it is nearly complete within 6 days and accounts for over 90% of a dose, mainly via urine. Only a trace amount is excreted in the feces [31,32].
