High-performance liquid chromatographic determination of chlordiazepoxide and major related impurities in pharmaceuticals

Determination of chlordiazepoxide, its hydrochloride and related impurities in pharmaceutical formulations by reversed-phase high-performance liquid chromatography

A quantitative high-performance liquid chromatographic method using an octadecylsilane column and a methanol-water mobile phase was employed for the determination of chlordiazepoxide, chlordiazepoxide X HCl and related impurities in capsule and tablet preparations. Each component is well separated and directly detected by 254 nm absorption. For chlordiazepoxide and chlordiazepoxide X HCl the coefficient of variation for replicated injections was below 1%. Recovery of authentic samples ranged from 98.4 to 101.6% for both capsule and tablet formulations.

Assay of chlordiazepoxide and demoxepam in chlordiazepoxide formulations by difference spectrophotometry

Rapid difference spectrophotometric methods for chlordiazepoxide and demoxepam in chlordiazepoxide formulations are described which overcome the nonspecificity of the official spectrophotometric assays. The procedures are based on the measurement of the difference absorbance at 269 nm of equimolar solutions of chlordiazepoxide at pH 8 and pH 3 and the difference absorbance at 263 nm of equimolar solutions of demoxepam at pH 13 and pH 8. The methods are specific for chlordiazepoxide and demoxepam in the presence of both compounds, 2-amino-5-chlorobenzophenone, certain coformulated drugs, and formulation excipients. Analyses of commercial dosage forms of chlordiazepoxide have shown the presence of demoxepam at concentrations in excess of the pharmacopoeial specifications in some aged samples.

Routine quality evaluation of benzodiazepine drugs to USP-NF specifications

A GLC procedure was developed for the evaluation of diazepam, chlordiazepoxide, and flurazepam formulations to USP-NF specifications for drug content, content uniformity, impurities, and identity by retention times and peak areas. The polyimide column, instrument zone temperatures, gas flows, internal standard solution, extraction solvent, and auxiliary equipment were the same for each drug. No derivatization of the samples was required. The GLC assay values (mean of 10 individual dosage units) for diazepam and flurazepam products were in good agreement with the results obtained by the pharmacopeial composite assays. With chlordiazepoxide capsules, when the levels of the two pharmacopeial impurities determined by GLC were added to the GLC assay results (mean of 10), athe aggregate values were consistent wit the drug content results found by the nonspecific USP method. The procedure can be made sensitive to impurity levels of approximately 0.01% for 2-amino-5-chlorobenzophenone and to approximately 0.2% for 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one 4-oxide. With the equipment used, the estimated potential outputs in lots per working day for a complete quality profile (drug content, content uniformity, purity, and identity) were seven for chlordiazepoxide if no impurity test was required, five if such a test was required, eight for diazepam, and seven for flurazepam.

Formation of thermally stable derivatives of chlordiazepoxide and its desmethyl metabolite for GLC

A derivatization procedure is described for the GLC determination of subnanogram amounts of chlordiazepoxide and nanogram amounts of N-desmethylchlordiazepoxide. Treatment with acetic anhydride at elevated temperature eliminates the highly polar and unstable nitrone group of these compounds by rearrangement and acetylation. The mass spectrometric fragmentation pattern of the acetyl derivatives is recorded and interpreted.