Experimental Studies of Methemoglobinemia Due to Percutaneous Absorption of Sodium Nitrite

Abstract Objective: Methemoglobin formation caused by a liniment solution containing sodium nitrite (30 g/L and 140 g/L) was studied in rats with normal or abraded skin, by measuring the methemoglobin concentration before and after application of liniment solutions with differing nitrite concentration. Methods: Each liniment solution (120 μL) was applied. Methemoglobin was measured for 180 minutes using a hemoximeter. Simul-taneously, arterial blood pressure and cutaneous blood flow was measured by laser Doppler flowmetry and a pressure transducer. Results: After the application of each liniment solution to normal skin, the methemoglobin concentration was not significantly modified depending on the time after application. Application of liniment solution to abraded skin (140 g/L) resulted in a marked increase in methemoglobin concentration. A remarkable decrease in arterial blood pressure and subcutaneous blood flow were observed after application of liniment solution to abraded skin (140 g/L). Conclusions: Each of these findings are characteristic of nitrite and they imply the percutaneous absorption of nitrite. Regardless of the nitrite concentration, the methemoglobin concentration was consistently higher in abraded skin than in normal skin