Phentermine, detection

Disposition in the Body. Readily absorbed after oral or parenteral administration and rapidly metabolised by demethylation and hydroxylation. About 50 to 85% of a dose is excreted in the urine unchanged, together with 15 to 20% as phentermine. Conjugated A -hydroxymephentermine has also been detected in the urine in small quantities. 

In a fatality involving the ingestion of phentermine, the following postmortem tissue concentrations were reported blood 7.6 pg/ml, kidney 16 pg/g, liver 14 pg/g, urine 88 pg/ml amylobarbitone and ethchlorvynol were also detected in blood at concentrations of 10 pg/ml and 12 pg/ml, respectively (B. Levine eta/., J.forens. Sci., 1984,29,1242-1245). 

The retention characteristics of sixteen phenylalkylamine derivatives (e.g., amphetamine, phentermine, 5-methoxy-3,4-methylenedioxyamphetamine, mescaline, methoxamine) were monitored on a 40°C C g column (photodiode array detector, A= 190-300nm) using a complex 22-min 5.5/94.5-> 39/61 (90/10 acetonitrile/water [5mL/L H3PO4 and 0.28 mL/L hexylamine])/water (5mL/L H3PO4 and 0.28 mL/L hexylamine) gradient [1425]. Urine and cactus samples were extracted and detection limits of 25-50 ng/mL and 40ng/g, respectively, were reported. 

The method described herein allows the analysis of the eight most commonly used amphetamines. The order of elution was phenyletylamine, followed by amphetamine, phentermine, fenfluoramine, methamphetamine, MDA, MDMA, and 2C-B. The limit of detection, linearity range, and correlation coefficients of the calibration curves obtained for the different amphetamines are shown in Table 14.2. The intraday and interday coefficients of variation for concentrations of 5 ng/mL, 50 ng/mL, and 500 ng/mL were 1.17%, 2.98% and 12.2%, respectively. 

Kaddoumi, A. Kubota, A. Nakashima, M.N. Takahashi, M. Nakashima, K. High performance liquid chromatography with UV detection for the simultaneous determination of sympathomimetic amines using 4-(4,5-diphenyl-lH-imidazole-2-yl)benzoyl chloride as a label, Biomed.Chromatogr., 2001, 15, 379-388. [human rat plasma derivatization LOD 50-100 nM ephedrine norephedrine 2-phenylethylamine fenfluramine phentermine cyclohexylamine fluoxetine is internal standard pharmacokinetics]... 

Kaddoumi, A. Nakashima, M.N. Nakashima, K. Fluorometric determination of DL-fenfluramine, DL-norfenfluramine and phentermine in plasma by achiral and chiral high-performance liquid chromatography, J.Chromatogr.B, 2001, 763, 79-90. [fluorescence detection derivatization human rat LOD 10 nM ephedrine norephedrine]... 

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