Biotransformation and urinary excretion of 4-substituted amphetamines in pregnant mice

Metabolic pathways of 4-bromo-2,5-dimethoxyphenethylamine (2C-B): analysis of phase I metabolism with hepatocytes of six species including human

4-Bromo-2,5-dimethoxyphenethylamine (2C-B) is a psychoactive designer drug of abuse that is sold under the street names "Venus", "Bromo", "Erox", "XTC" or "Nexus". Concern has been raised because only little is known about its toxicity and metabolism in humans. In the present study we incubated 2C-B with human, monkey, dog, rabbit, rat and mouse hepatocytes to identify the metabolites formed and to determine possible toxic effects as evidenced by an ATP assay. Our data allow construction of the main metabolic pathways of 2C-B. Oxidative deamination results in the 2-(4-bromo-2,5-dimethoxyphenyl)-ethanol (BDMPE) and 4-bromo-2,5-dimethoxyphenylacetic acid (BDMPAA) metabolites. Additionally, 4-bromo-2,5-dimethoxybenzoic acid (BDMBA) can be produced also by oxidative deamination. Further metabolism of BDMPE and BDMPAA may occur by demethylation. Alternatively, the later metabolites can be generated by demethylation of 2C-B followed by oxidative deamination. Two remarkable interspecies differences in metabolism of 2C-B were observed (i) a hitherto unknown metabolite, 4-bromo-2,5-dimethoxy-phenol (BDMP), was identified after incubation only with mouse hepatocytes; (ii) 2-(4-bromo-2-hydroxy-5-methoxyphenyl)-ethanol (B-2-HMPE) was produced by hepatocytes from human, monkey and rabbit but not by dog, rat and mouse. Comparing the toxic effects of 2C-B between hepatocytes of the six examined species we observed only minor interspecies differences. However, large inter-individual differences in susceptibility of hepatocytes from three human donors were observed.

Developmental toxicity of 4-substituted amphetamines in mice

Despite overwhelming and tragic evidence of their detrimental and dangerous consequences, amphetamines remain significant drugs of abuse and addiction. The effects of 4-substituted amphetamines: 4-hydroxyamphetamine (4-HA), 4-methoxyamphetamine (4-MEA), 4-ethoxyamphetamine (4-ETA), 4-propoxyamphetamine (4-PPA), and 4-benzyloxyamphetamine (4-BEA) on intrauterine development, pregnancy outcome, postnatal growth, and survival were compared in Swiss-Webster mice. Single daily doses (0, 50, or 100 mg/kg) of an aqueous solution of different amphetamines were administered on pregnancy days 6 through 18. The 50 mg/kg doses of all amphetamines were well tolerated by the mothers and did not produce any overt signs of maternal toxicity or death. However, a few mothers died on different days of gestation after receiving 100 mg/kg of 4-HA, 4-MEA, 4-ETA, and 4-BEA. The mothers that failed to deliver naturally (3 d after the due date) were killed and their uteri were examined for live/dead fetuses and resorption sites. In comparison with respective controls, the incidence of resorptions was markedly higher in the 4-MEA- and 4-ETA-dosed groups. Delivery was prolonged in the 4-PPA- and 4-BEA-treated dams. Apparently well-formed but dead pups were delivered by 4-HA-, 4-PPA-, and 4-BEA-dosed mice. Marked reductions in average litter size and weight occurred after intrauterine exposure to 100 mg/kg 4-BEA. Treatment with 4-ETA, 4-PPA, and 4-BEA not only resulted in a high incidence of cannibalism within 24 h after birth but also caused an increase in cumulative pup mortality during the first 3 weeks of age. Body weight gain was significantly lower in 3-week-old offspring exposed to 4-HA and 4-PPA than in the controls. The findings suggest that 4-substituted amphetamines exhibit a wide variation in their effects on maternal toxicity and pregnancy wastage, and produce adverse effects on parturition, pup survival, and postnatal development.

The influence of pregnancy on the biotransformation and urinary excretion of methoxyphenamine in mice

(i) The urinary elimination of methoxyphenamine (MPA) and its metabolites in underivatized samples was examined after single and multiple oral administration to pregnant and non-pregnant mice by GLC and GLC-MS. (ii) The major metabolite O-desmethylmethoxyphenamine (ODMP), along with lesser amounts of N-desmethylmethoxyphenamine (NDMP) and 2-hydroxyamphetamine (2OH), were the only metabolites detected in urine extracts of pregnant and non-pregnant mice. 5-Hydroxymethoxyphenamine (5HMP) was not detected. Enzyme hydrolysis did not increase the recovery of either substrate or metabolites in either the pregnant or non-pregnant animals. The results show that MPA metabolism in the Swiss-Webster mouse is distinctly different from that seen in man and other laboratory animals. (iii) The mean MPA:ODMP ratio in day-6 urine from pregnant mice after a single dose was 0.31 +/- 0.04. The NDMP:ODMP ratios were less than 0.10 in all samples. Non-pregnant mice urine had equivalent amounts of MPA, NDMP, ODMP, and 2OH after multiple dosing. (iv) While multiple dosing and pregnancy did not alter either the urinary recovery or profile of the metabolites detected, there was a linear decrease in the MPA:ODMP ratio during gestation. (v) MPA was extensively metabolized to ODMP in the male mice, and the MPA:ODMP ratio of 0.41 was slightly higher than that observed in the pregnant and non-pregnant females.