Received for publication September 22, 2006.
Revised November 7, 2006.
Accepted for publication November 8, 2006.

Triethylenetetramine (TETA) and metabolites: levels in relation to copper and zinc excretion in urine of healthy volunteers and type-2 diabetic patients

Abstract

Triethylenetetramine (TETA), a selective Cu^II-chelator used in the treatment of Wilson's disease, is now undergoing clinical trials for the treatment of heart failure in diabetes. Despite decades of clinical use, knowledge of its pharmacology in human subjects remains incomplete. Here, we first used liquid chromatography- mass spectrometry (LC-MS) to detect and identify major metabolites of TETA in human plasma and urine, and then used this method to measure concentrations of TETA and its metabolites in the urine of healthy and diabetic subjects. Healthy and diabetic subjects were administered various doses (300, 600, 1200 and 2400 mg) of TETA orally. Twenty-four-hour urine collections were performed before and after dosing participants. Two major metabolites of TETA were detected in human urine, N₁-acetyltriethylenetetramine (MAT) and N_1,N₁₀- diacetyltriethylenetetramine, the latter being novel. Both metabolites were verified by synthetic standards on LC-MS. The proportion of unchanged TETA excreted as a fraction of total urinary drug-derived molecules, was significantly higher in healthy than in matched diabetic subjects, consistent with a higher rate of TETA metabolism in the latter. TETA-evoked increases in urinary Cu excretion in non-diabetic subjects were more closely correlated with parent drug concentrations than in diabetic subjects whereas, by contrast, urinary Cu was more closely associated with the sum of TETA and MAT. These findings are consistent with the hypothesis that MAT could play a significant role in the molecular mechanism by which TETA extracts Cu^II from the systemic compartment in diabetic subjects.

Key words: acetylation, drug analysis, excretion, HPLC, mass spectrometry, metabolite identification, phase II drug metabolism