Assiut university researches
Analytical Study Using Spectrometric and
Chromatographic Methods for Some
Angiotensin II Receptor Antagonists
‫درا سة ت ح ل ي ل ية ب ا س تخدام طرق ط ي ف ية‬
.‫وك رومات وجراف يا ل ب عض م ضادات االن ج يوت ن س ين‬
Ahmed Abd-El Hameed Khorshed
‫أحمد ع بدال حم يد خور شد‬
Samiha Abd-El Rahman Hussein, Hanaa Mohamed Abd-El Wadood,
Mohamed Abdel Galil Abou-Elwafa.
‫ محمد ع بدال ج ل يل أب وال وف ا‬،‫ ه ناء محمد ع بدال ودود‬،‫سم يحة ع بدال رحمن ح س ين‬
Abstract:
The present thesis concerned with spectrometric and HPTLC
analysis of some ARBs compounds namely: losartan,
irbesartan, valsartan and olmesartan in pure, tablets and
spiked human plasma. The thesis comprises an introduction
and 3 main chapters Introduction It is an introductory part
which includes general introduction about ARBs, their
medicinal importance, the chemical structure, and physical
properties of the target drugs. The introduction also included
a literature review of the official and reported analytical
methods used for the drugs determination. It also included
the scope of the research. Chapter I: Chapter I includes five
simple spectrophotometric methods for determination of
irbesartan and olmesartan and one method for losartan. They
were developed for the determination of the studied drugs
through charge transfer reaction between the prepared salts
of the studied drugs as electron donors and p-CA, bromanil,
DDQ, picric acid and TCNQ as electron acceptors.
Preparation of the drug salts was used for the first time to
increase electron density on the tetrazole ring which is the
site of the reaction and as a result increase the sensitivity of
the proposed methods. The reaction accompanied by shift of
the maxima of the drug from 205 nm to 517, 507, 460, 380
and 842 nm for p-CA, bromanil, DDQ, picric acid and TCNQ
respectively away from the co-formulated HCZ spectrum
which completely overlapped with the spectra of the studied
drugs. A study for all variables was carried out to optimize the
reaction conditions. A validation study was performed for the
proposed procedure according to USP XXXI (2008) and ICH
validation guideline (2005). Under the optimal reaction
conditions, linear relationships with good correlation
coefficients (0.9984 – 0.9999) were found between
absorbance and concentration of the investigated drugs in the
range of 1 – 250 μg/ ml. The detection limits ranged from 0.15
to 9.90 μg/ ml, while the quantification limits ranged from 0.46
to 30 μg/ ml. The methods were successfully applied for the
analysis of the studied drugs in pure form and tablets. Results
were compared with those obtained by reported methods.
The t- and F values were calculated and compared with the
theoretical values, which indicated high accuracy and
precision of the proposed methods. Summary 157 Chapter II:
Chapter II included a simple and sensitive spectrofluorimetric
method for the quantification of olmesartan, valsartan and
irbesartan in bulk, tablets and spiked human plasma. The
method based on measuring the native fluorescence using
very simple procedure. Under the optimal reaction conditions,
linear relationships with good correlation coefficients (0.9989
–0.9998) were found between absorbance and concentration
of the investigated drugs in the range of 1 – 25 ng/ ml. The
detection limits were in the range of 0.10 – 0.40 ng/ ml, while
the quantification limits were in the range of 0.32 – 1.22 ng/
ml. the method was applied successfully for drugs
determination in tablets. The high sensitivity obtained by the
proposed methods allowed the determination of the studied
drugs in spiked human plasma, without interference from the
constituents of the plasma. Chapter III: This chapter consists
of two parts, the first part deals with simultaneous
determination of the studied drugs by two HPTLC methods
using reflectance/ absorbance and reflectance/ fluorescence
modes. The separation was based on using HPTLC plates
pre-coated with silica gel 60 on aluminum sheets as
stationary phase. The mobile phase used composed of
(chloroform: glacial acetic acid 7.5: 2.5 v/v) which allowed
complete resolution between the studied ARBs and this gave
the method a great selectivity due to its ability to distinguish
each member. The possibility of simultaneous quantification
and identification of the active ingredient in the finished
product is therefore very attractive from the analytical
viewpoint. Under the optimal conditions, linear relationships
with good correlation coefficients (0.9988 – 0.9999) were
found between peak area and concentration of the
investigated drugs in the ranges of 90 – 750 ng per band and
2- 120 ng per band for reflectance/absorbance and
reflectance/fluorescence methods respectively. The detection
limits were in the range of 14.85 – 30.42 ng per band and
0.55 – 0.81 ng per band, while the quantification limits were in
the range of 45.00 – 92.18 ng per band and 1.67 – 2.44 ng
per band for the reflectance/absorbance and Summary 158
reflectance/fluorescence methods respectively. The two
methods were applied successfully for the determination of
the studied drugs in tablets and plasma with a good accuracy
and precision. The second part, involved a stability indicating
assay of irbesartan by reflectance/ absorbance and
reflectance/ fluorescence modes in pure, tablets and spiked
human plasma by the reflectance/ fluorescence mode without
any interference from acidic, alkaline, oxidative and UV
degradations. The degradation pathways under all the
studied conditions were suggested and confirmed by IR and
GC Mass spectrometric techniques. Under the optimal
conditions, linear relationships with good correlation
coefficients 0.9998 and 0.9974 were found between peak
area and concentration of the investigated drugs in the range
of 210 – 900 ng per band and 7- 90 ng per band. The
detection limits were 14.23 ng per band and 1.98 ng per
band, while the quantification limits were 43.12 ng per band
and 6.02 ng per band for the reflectance