The possibilities of degradation of nitrazepam and its methyl derivative (nimetazepam) in the presence of human faecal flora were investigated. After combination of nitraze-pam or nimetazepam with sterilized broth (pH 7.10, 7.18), 1% (pH 6.63, 6.72) or 8% (pH 6.20, 6.37) sterilized stool culture without further anaerobic precautions, the drugs did not degrade in an incubation mixture. This indicates that the drugs did not react with the components of broth and stool cultures, and were stable at these pH values. On the other hand, after combination of the drugs with 1% or 8% human faecal contents in a broth , the drugs disappeared rapidly in the incubation mixture in proportion to stool concentrations. The metabolite of nitrazepam was identified to be 7-aminonitrazepam by a high performance liquid chromatography (HPLC) and thin-layer chromatography. The degradation patterns of nitrazepam and nimetazepam were followed by HPLC. Keywords intestinal microflora; faecal flora; intestinal drug metabolism; nitro reduction; bioavailability; nitrazepam; nimetazepam; 7-aminonitrazepam; HPLC; TLC ƒj ƒgƒ‰ƒ[ ƒp ƒ€ ‚AE ƒj ƒgƒ‰ƒ[ ƒp ƒ€ ‚ÌN-1ˆÊ ƒ• ƒ` ƒ‹'Ì ‚Ì ƒj ƒ• ƒ^ƒ[ ƒp ƒ€‚Í ,7-ƒj ƒgƒ•-1,4-ƒxƒ" ƒ] ƒWƒA ƒ[ ƒs ƒ"-Þ ‚Å ‚ ‚è, '¼ ‚Ì1,4-ƒx ƒ" ƒ]ƒW ƒA ƒ[ ƒs ƒ"-Þ ‚AE"¯-l ‚É•Ã-°,•R •s ˆÀ,‹Ø 'o ŠÉ,•R áz ‚ê ‚ñ "™ ‚Ì-ò-• Šˆ•Šˆ•« ‚ðŽ¦ ‚µ,-Õ •° "I ‚É ‚Í •Ã-°-ò ‚AE ‚µ‚Ä-p ‚¢ ‚ç‚ê ‚Ä ‚¢ ‚é.ƒj ƒgƒ‰ƒ[ ƒp ƒ€‚Í •¬ Ž™ ‚Ì ƒ~ƒI ƒN ƒ• ƒj •["-•ì1)‚É 'Î ‚· ‚é•R ‚Ä ‚ñ ‚© ‚ñ-ò ‚AE ‚µ‚Ä ‚àŽg-p ‚³‚ê ‚Ä ‚¢ ‚é. Rieder2)‚Í OE' •N •¬ •l6•l ‚É10mg‚Ì ƒj ƒgƒ‰ƒ[ ƒp ƒ€‚Ì Žs "Ì •» •Ü ‚ðOEo OEû"I ‚AEOEo •Ã-¬ "I ‚É"Š-^ ‚µ‚Ä"ä Šr ‚µ‚½ .‚» ‚Ì OE‹ ‰Ê OEo OEû"Š-^ OEã ‚Ì OEOE ' † "Z "x ‹È•ü ‰º-Ê •Ï ‚Í '• ŽË Žž ‚Ì53-94%(•½ ‹Ï78%)‚Å ‚ ‚Á ‚½ ‚ª,ƒo ƒCƒI ƒA ƒx ƒC ƒ‰ ƒr ƒŠƒe ‰º ‚Ì-•-R ‚AE ‚µ‚Ĉ݉t‚µ‚Ĉ݉t ‚Ì‹-‚¢‰-Ž_ ‚É '· ‚¢ ŠÔ ‚³ ‚ç ‚³‚ê ‚é ‚± ‚AE ‚É ‚ae ‚è2-ƒA ƒ~ƒm-5-ƒj ƒgƒ•ƒx ƒ" ƒ] ƒt ƒF ƒm ƒ"‚ª • ¶ •¬ ‚· ‚é‚© ‚ç‚Å ‚Í ‚È ‚¢ ‚© ‚AE•ñ •• ‚µ‚½. ‚±‚ê ‚AEŠÖ˜A‚AEŠÖ˜A ‚µ‚Ä '˜ ŽÒ ‚ç3)‚Í ‚· ‚Å ‚É ƒj ƒgƒ‰ ƒ[ƒp ƒ€ ‚AE ƒj ƒ• ƒ^ƒ[ ƒp ƒ€‚̈݃€‚ÌˆÝ "àŽ_ •« •ð OE• ‰º ‚É ‚¨‚¯‚¨‚¯ ‚鉻 Šw "I ˆÀ 'è •« ‚É‚Â ‚¢ ‚Ä OEŸ "¢ ‚µ,‚± ‚ê ‚ç‚Ì-ò •¨ ‚Í Ž_ •« •ð OE• ‰º ‚Å ƒA ƒ] ƒ•ƒ` ƒ"OE‹ • ‡ ‚ª •Ø ‚ê ‚Ä ŠJ ŠÂ ‚· ‚邪pH‚Ì •ã •¸ ‚É "º ‚Á‚Ä ƒA ƒ]ƒ• ƒ` ƒ"OE‹ • ‡ ‚ª •Ä ‚Ñ • ¶ •¬ ‚· ‚é •Â ŠÂ "½ ‰ž(ƒj ƒgƒ‰ ƒ[ ƒp ƒ€‚ ‚é‚¢ ‚Í ƒj ƒ•ƒ^ ƒ[ ƒp ƒ€‚Ì • ¶ •¬)‚Ì '¬ "x ‚Í-¼ ŽÒ ‚Å •· ‚ª ‚ ‚é ‚± ‚AE‚ð •ñ •• ‚µ‚½. ƒj ƒgƒ‰ ƒ[ ƒp ƒ€ ‚Ì'ã ŽÓ •¨ ‚AE ‚µ ‚Ä ‚Í ,7-ƒj ƒgƒ•Šî ‚ÌŠÒ OE³ ‚É ‚ae ‚é7-ƒA ƒ~ ƒmƒj ƒgƒ‰ƒ[ ƒp ƒ€,‚» ‚ê ‚É '± ‚-ƒAƒZ ƒ` ƒ‹ ‰» ‚³‚ê ‚½7-ƒA ƒZ ƒ` ƒ‹ ƒA ƒ~ ƒmƒj ƒgƒ‰ƒ[ ƒp ƒ€,‚» ‚Ì'¼ ‚É3ˆÊ ‚Ì •… Ž_ ‰» •¨ ‚È ‚Ç‚ª•ñ •• ‚³‚ê ‚Ä ‚¢ ‚é.4)ƒj ƒ•ƒ^ ƒ[ ƒp ƒ€‚Ì 'ã ŽÓ •¨ ‚AE ‚µ‚Ä ‚Í7-ƒj ƒgƒ•Šî ‚ÌŠÒ OE³ ‚É ‚ae ‚é7-ƒA ƒ~ƒm ƒj ƒ• ƒ^ ƒ[ƒp ƒ€,‚» ‚ê ‚É '± ‚-7-ƒA ƒZ ƒ` ƒ‹ ƒA ƒ~ ƒmƒj ƒ•ƒ^ ƒ[ ƒp ƒ€‚È ‚Ç‚Ì ‚Ù ‚© , • ¶-• Šˆ•Šˆ•« 'ã ŽÓ •¨ ‚AE ‚µ‚Ä1-N-'E ƒ• ƒ` ƒ‹'Ì,‚· ‚È ‚í ‚¿ ƒj ƒgƒ‰ ƒ[ƒp ƒ€ ‚AE‚» ‚Ì'ã ŽÓ •¨ ‚à•ñ •• ‚³‚ê ‚Ä ‚¢ ‚é .5) •Á ‰» ŠÇ "à •× ‹Û ‚ª '½ ‚-‚Ì-L‹@ ‰» • ‡ •¨ ‚̉» Šw •ÏŠ· ‚ð •s ‚¤‚± ‚AE‚Í ‚· ‚Å ‚É 'm ‚ç‚ê ‚Ä ‚¢ ‚é.6)OEo OEû"Š-^ ‚³‚ê ‚½-ò •¨ ‚ª ‚±‚Ì ‚ae ‚¤‚È •Á ‰» ŠÇ "à •× ‹Û ‚É ‚³ ‚ç ‚³‚ê ‚Ä •ª ‰ð ‚· ‚é ‚AEƒo ƒCƒI ƒAƒx ƒC ƒ‰ ƒr...

Effects of amitriptyline and isocarboxazid on brain 5-HT and 5-HIAA were examined in relation to their action on 5-HTP induced head twitches. Amitriptyline reduced 5-HTP induced head twitches but isocarboxazid increased them. Both amitriptyline and isocarboxazid caused a significant increase of brain 5-HT concentration in 5-HTP treated mice. Amitriptyline also caused a significant increase of 5-HIAA concentration, while isocarboxazid reduced 5-HIAA concentration in the brains of 5-HTP treated mice. Probenecid, which significantly increased 5-HIAA concentration without affecting brain 5-HT concentration in 5-HTP treated mice, reduced 5-HTP induced heat twitches. These results suggest that 5-HTP induced head twitches might be induced by an increase of 5-HT concentration, and reduced by an increase of 5-HIAA or a decrease of 5-HT concentration in the brains of mice.

1. Blood levels of nimetazepam after oral administration to dogs were relatively low at early periods after dosage and reached peak levels (7-7-7-9 mug equiv./ml) after 8 h. The time course of blood levels was similar after oral administration of its desmethyl derivative (nitrazepam) to dogs. Blood levels of the latter, however, were low compared with nimetazepam and reached a peak (5-2-6-3 mug equiv./ml) after 4 h. 2. Recoveries of nimetazepam in urine and faeces were 46 and 52% of the dose for 0-24 h, 27 and 34% for 24-48 h and 4 and 6% for 48-72 h, while those of its desmethyl derivative (nitrazepam) were 63 and 71% for 0-24 h, 12 and 21% for 24-48 h and 2 and 3% for 48-72 h. 3. At least four kinds of reaction were involved in the biotransformation of nimetazepam and its desmethyl derivative (nitrazepam): (i) demethylation at N-1 (ii) hydroxylation at C-3, (iii) subsequent glucuronic acid conjugation of 3-hydroxy derivatives and (iv) reduction of the nitro group at C-7 to an amino group. Reaction (i) proceeded very rapidly in dogs, so that the blood metabolites of nimetazepam were closely similar to those of nitrazepam. For both drugs, the major blood metabolite was nitrazepam. Reaction (ii) was rapidly followed by reaction (iii), and glucuronides were predominantly excreted in urine. Reaction (iv) as well as reaction (iii) are important in the excretion of both drugs. The subsequent acetylation of 7-amino group, however, did not occur in dogs as it did in mice and rats.