The use of 13C-nmr spectroscopy for the detection and identification of metabolites of carbon-13 labelled amitriptyline.
The antidepressant drug amitriptyline and two of its metabolites, nortriptyline and desmethylnortriptyline, each containing two 13C atoms, have been used to determine the sensitivity and selectivity of 13C-nmr spectroscopy for the detection of unchanged amitriptyline and N-desmethyl metabolites in the urine of animals dosed orally with the labelled drug. The resonance signals from the 13C atoms detected in the 13C-nmr spectrum of entire extract from a control 12 h rat urine sample to which 1 mg of each labelled compound had been added were easily detected, using an instrument accumulation time of 1 h. The 13C-nmr spectrum of an extract of hydrolysed urine from a dog that had received an oral dose of  [13C2]amitriptyline (30mg) exhibited signals that could be assigned to metabolites resulting from N-dealkylation and N-oxidation, as well as those bearing the intact amitriptyline side-chain. These assignments were confirmed by analysis of the same extract by g.c.--ms and h.p.l.c.
D000639:Amitriptyline / Q000378:metabolism*; D000818:Animals; D002247:Carbon Isotopes; D002851:Chromatography, High Pressure Liquid; D003640:Dealkylation; D004285:Dogs; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D013058:Mass Spectrometry; D051381:Rats
D002247:Carbon Isotopes; D000639:Amitriptyline