Quantitative determination of diazepam, nitrazepam and flunitrazepam in tablets using thin-layer...

Area of Science:

• Analytical Chemistry
• Pharmaceutical Analysis

Background:

• Accurate quantification of active pharmaceutical ingredients (APIs) in tablets is crucial for quality control.
• Benzodiazepines like diazepam, nitrazepam, and flunitrazepam are widely prescribed, necessitating reliable analytical methods.

Purpose of the Study:

• To develop and validate a simple and reliable assay for determining diazepam, nitrazepam, and flunitrazepam content in tablet formulations.
• To compare the efficacy and practicality of high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC)-densitometry for this analysis.

Main Methods:

• Tablets were ground, and the active ingredients were extracted using methanol.
• Analysis was performed using both HPLC with a C18 reversed-phase column and TLC-densitometry on silica gel plates.
• Both methods utilized a variable UV detector set at 254 nm.

Main Results:

• Both HPLC and TLC-densitometry provided reliable quantification of the benzodiazepines.
• One brand of diazepam tablets was found to contain 23% less active ingredient than the minimum prescribed amount.
• TLC-densitometry yielded slightly higher results than HPLC but is considered superior due to its simplicity and lower cost.

Conclusions:

• A simple and reliable HPLC and TLC-densitometry assay is effective for quantifying diazepam, nitrazepam, and flunitrazepam in tablets.
• TLC-densitometry is the preferred method for routine tablet analysis due to its simplicity, ease of use, and cost-effectiveness.
• The assay identified a potential quality control issue in one brand of diazepam tablets.