Elucidation of Degradation Behavior of Nitrazepam, a Benzodiazepine Drug, under Basic Conditions: Study on Degradability of Drugs in Stomach (IV)

This study investigates the stability of nitrazepam (NZP), a benzodiazepine drug, under basic conditions, since alkaline putrefactive amines and ammonia are produced once bodies are left to decompose for a long period postmortem after a murder involving NZP or an accidental overdose of NZP. The degradation of NZP in an aqueous alkaline solution was investigated by LC/photodiode array detector (PDA) where the NZP degradation product was isolated and purified by solid-phase extraction using Oasis® MCX, and its chemical structure was determined by LC/time-of-flight (TOF)-MS, NMR spectroscopy, and single-crystal X-ray crystallography. The results revealed that NZP was immediately degraded under basic conditions with 2-amino-5-nitrobenzophenone being an intermediate which further degraded to provide 2-hydroxy-5-nitrobenzophenone as the final degradation product. These results are expected to be useful in clinical chemistry and forensic science, such as the detection of drugs during postmortem examination and suspected addiction.

[Cross-reactivity of Instant-View M-1 for detection of benzodiazepine-related drugs and their metabolites in urine]

Immunoassays are useful methods for the determination of regulated drugs in clinical and forensic laboratories. Although the Instant-View M-1 (IV M-1) immunoassay kit is frequently used to screen drugs in laboratories in Japan, basic information about the IV M-1 such as its specificity and reactivity is not available. In this study, we determined the specificity and cross-reactivity of IV M-1 for the detection of benzodiazepine-related drugs and their metabolites in urine. The IV M-1 could detect triazolobenzodiazepines such as triazolam in urine at concentrations > or = 300 ng/mL. However, thienodiazepines such as etizolam could not be detected because of lack of cross reactivity. A correlation was observed between the structure of the metabolites and the reactivity of the kit; 4-hydroxy metabolites of alprazolam and triazolam were detectable, whereas a-hydroxy metabolites were not. Furthermore, 7-amino metabolites such as nitrazepam could not be detected at any concentration, including high concentrations. The specificity and reactivity of various kits used for detection of drugs in urine are different. Therefore, it is necessary to consider the basic features of the kit used while assessing the results obtained.

Quantitative assessment of the effect of some excipients on nitrazepam stability in binary powder mixtures

The decomposition rate constants, normalized for dilution and relative specific surface effects. Of nitrazepam in simple binary powder mixtures with talcum, lactose-H2O, microcrystalline cellulose, corn starch, mannitol, and saccharose are shown to be linearly related to the nitrogen adsorption energy of the excipients.

1H-NMR investigations on the hydrogen bond formation between the tranquilizers diazepam and nitrazepam and some nucleobases

The formation of hydrogen bonds between the minor tranquilizers diazepam and nitrazepam and a few nucleobases was studied in deuterochloroform solution by means of proton magnetic resonance spectroscopy. The thermodynamic and spectroscopic data of the associations were evaluated on the basis of a dimer model, using the concentration dependent shifts of the protons involved in hydrogen bonds. The interactions of nitrazepam (deltaH0=-10 to -21 kJ/mol; deltaG025 -0.2 to -7.4 kJ/mol) were found to be stronger than those of diazepam (deltaH0=-10 to -13 kJ/mol; deltaG025=6.0 to 6.4 kJ/mol). The various binding sites of the benzodiazepines for hydrogen bonds are discussed.

The polarographic and spectral behaviour of some 1,4-benzodiazepine metabolites: application to differentiation of mixtures

Changes of ultraviolet absorption spectra with pH in solution were used to determine pKa values for four 1,4-benzodiazepine metabolites. 7-Acetamido-nitrazepam, desmethyl-diazepam and the chlordiazepoxide lactam all gave two pKa values, corresponding to protonation in acid and deprotonation of the neutral molecule in alkaline media. 7-Amino-nitrazepam gave three pKa values, the third one being due to an additional protonation in acid media. The spectra are explained by considering them to be superimposed spectra of the two benzene rings, one mono-substituted (band I) and one trisubstituted (band II), within the molecule. Sites of protonation and deprotonation are predicted and the differences in the observed pKa values explained. Differences in the pKa values or the polarographic behaviour between the parent compounds and some of their metabolites are then used to effect novel separations after solvent extractions from aqueous buffered solutions.

An examination of acid-base equilibria of 1,4-benzodiazepines by spectrophotometry

Changes of ultraviolet absorption spectra with pH in solution were used to determine pKa values for six 1,4-benzodiazepines. Diazepam, chlordiazepoxide and medazepam as a result of protonation of the molecule in acidic solutions, were found to each have one pKa, while two pKa values were observed for oxazepam, nitrazepam and lorazepam, because of protonation in acid and deprotonation of the neutral molecule in alkaline media. The spectra are explained by considering them to be superimposed spectra of the two benzene rings, one mono-substituted and one tri-substituted, within the molecule. Sites of protonation (principally at nitrogen atoms in position 4 in the diazepine ring) and deprotonation (for oxazepam, nitrazepam and lorazepam) are predicted and the differences in the observed pKa values explained.