2,3 Dimercaptopropanol (BAL, British Anti-Lewisite) is now recognized as a specific drug in the treatment of arsenical poisoning. Many reports in the past two years have attested its value in the treatment of exfoliative dermatitis, blood dyscrasias and "hemorrhagic encephalitis" following the use of the trivalent arsenicals in the treatment of syphilis.1 A search of the recent literature reveals no reports of tryparsamide optic neuritis treated with BAL. This is a report of the first case of tryparsamide optic neuritis treated successfully with BAL.
The pharmacologic rationale for the use of BAL in arsenical (or mercury) poisoning is based on the theory that arsenicals are toxic because they block the functioning of physiologically essential chain groups within the cell by combining with them. The sulfhydryl grouping (-SH) is most vulnerable. BAL, a dithiol, competes successfully for the arsenic with the sulfhydryl bond, forms a stable compound with the arsenic
FRIEDENBERG S. TRYPARSAMIDE OPTIC NEURITIS TREATED BY 2,3 DIMERCAPTOPROPANOL (BAL). JAMA. 1947;135(16):1072. doi:10.1001/jama.1947.62890160012007