Journal of Clinical & Experimental Pharmacology

Abstract

O-Toluidine in Breath-Non-Invasive Prilocaine Monitoring

Brock B, Kamysek S, Trefz P, Fuchs P, Timm U, Miekisch W and Schubert JK

The generation of methaemoglobin is a rare but potential life-threatening side effect in the use of the local anaesthetic prilocaine. It is currently only possible to ensure the diagnosis by means of blood tests. Rapid noninvasive diagnosis is desirable, especially for risk patients.

Using a pig model, we induced methaemoglobinemia via application of dimethyl aminophenol and prilocaine (setup I) or natrium nitrite and prilocaine (setup II). Continuous real time breath gas monitoring was performed by proton transfer reaction-time-of-flight-mass spectrometry (PTR-TOF-MS) for non-invasive determination of volatile organic compounds (VOCs).

O-Toluidine, the main metabolite of prilocaine, could be detected in alveolar breath gas by means of PTR-TOFMS and was confirmed by NTME-GC-MS (needle trap micro-extraction gas chromatography-mass spectrometry). The administration of prilocaine intravenously was clearly reflected with a time lag of a few min by the detection of O-Toluidine in the respiratory gas.

If reliable correlations between prilocaine and methaemoglobin concentrations in blood and O-Toluidine levels in breath can be established, detection of prilocaine induced methaemoglobinemia and prevention of prilocaine poisoning with potentially life threatening hypoxia might be possible by means of non-invasive O-Toluidine analysis in breath.