Enantiomer Analysis of A New Street Drug, 3,4-Methylenedioxy-N-methyl-butanamine, in Rat Urine

I A new street drug, 3,4-methylenedioxy-N-methyl-butanamine (MBDB), has been found in Japan recently. The stereoisomer monitoring and the urinary excretion kinetics are not determined in biological fluids even though abused MBDB is a racemic form (enantiomer ratio (-/+) = 1.00). The present studies were done by high-performance liquid chromatography (HPLC) equipped with a chiral activity column at 40~ using urine specimens from five Wistar rats. Urine samples were collected over six time intervals after a single oral administration of racemic MBDB (30 mg/kg). Unchanged MBDB and 3,4-methylenedioxybutanamine (BDB), an N-demethylated metabolite, were found in the rats' urine. Each enantiomer of MBDB and BDB was monitored (peak resolution > 1.00) by HPLC analysis within 30 rain. For both MBDB and BDB, the (+)-isomers were excreted a little more than the (-)-isomers. The stereoselective disposition of BDB was more remarkable than that of MBDB and was observed in the urine throughout the study (p < 0.05). The urinary excretion of MBDB showed significant difference between the two enantiomers from 4 to 20 h (p < 0.05). The amount of MBDB excreted upto 24 h was 34.7 + 2.8% of the administered dose: 17.6  1.4% for (+)-isomer and 17.1  1.5% for (-)-isomer. The amount of BDB was 4.9  1.0%; 2.9 _+ 0.6% for (+)-isomer and 2.0 + 0.4% for (-)-isomer. The enantiomer ratio (-/+) of MBDB and BDB was 1.00 or a little smaller. The ratio (-/+) of MBDB changed from 1.00 r 0.02 to 0.88 r 0.09 by 24 h, and that of BDB from 0.68 r 0.03 to 0.78 r 0.02. The ratio (-/+) for MBDB and BDB accumulated up to 24 h was 0.97r 0.01 and 0.70 r 0.06, respectively, and the total ratio (-/+) of the two substances was 0.93 r 0.02 (p < 0.05). These findings suggested that the stereoselective disposition of racemic MBDB was different from that of 3,4-dimethylenedioxyamphetamine and 3,4- dimethylenedioxymethamphetamine and was similar to that of methamphetamine.