Purpose:
A simple, reliable and
rapid
chemical identification system (RCIS)
consisting of three colour reactions based on the
functional groups in the molecule and two TLC methods
was developed for preliminary detection of the 5–nitroimidazole
drugs.
Methods:
Three members of this group of drugs
(tablet form) available in the Nigerian market and
labelled MA and MB for
metronidazole, T A and TB for
tinidazole and S for secnidazole, were used. The
extraction of the active ingredient from the solid
dosage form was performed using acetone. The reaction of
the extracted drug with zinc and 1M hydrochloric acid at
100 oC converted the nitroimidazole group to
a characteristic primary aromatic amine. TLC methods A
and B were carried out on GF254 plates (5cm x
10cm) to further identify the individual members of the
group. TLC method A with mobile phase consisting of
acetone, ethyl acetate and ammonia (100:5:1) and method
B with mobile phase consisting of acetone, chloroform
and ammonia (100:15:1) were developed for the
identification.
Results: The aromatic character of 5-nitroimidazole was highlighted
in nitric acid when combined with sulphuric acid
resulting in an orange colour. 40% sodium hydroxide gave
the alkali-induced characteristic orange colour of
aromatic amino compounds. All the samples of the various
brands gave characteristic colours that distinguished
the compounds of the 5-nitroimidazole group as primary
or secondary nitroimidazole compounds.
Conclusion: Using the developed method, fraudulently labelled product
5-nitroimidazole antiprotozoal and antibacterial agents
can now be detected in approx. 40 min with limited
reagents and a simple TLC technique. The method is
rugged, simple, and should be particularly handy for use
in detecting substandard products of the drug in the
drug distribution chain where sophisticated equipment
are often not available.
Keywords:
5–nitroimidazole; Fraudulently labeled;
Chemical identification system; Antiprotozoal;
Antibacterial.
