INTRODUCTION: ANALYTICAL CHEMISTRY: Analytical chemistry1 is the branch of chemistry involved in separating, identifying
and determining the relative amounts of the components making up a sample of
matter. It is mainly involved in the qualitative identification or detection of
compounds and the quantitative measurement of the substances present in bulk and
pharmaceutical preparation.
The newer methods for separating and determining chemical species are known
collectively as instrumental methods of analysis. Most of the instrumental methods fit
into one of the three following categories viz., spectroscopy, electrochemistry and
chromatography. CHROMOGENIC REAGENTS USED IN THE PRESENT INVESTIGATION: Functional groups present in organic drugs determine the way of analyzing
them because they are responsible for the properties of substances and determine the
identification reaction and the methods of quantitative determination of drugs.
Knowing the reactions for detecting functional groups, one can easily analyze any
organic drug with a complicated structure. In the present investigation, few visible
spectrophotometric methods have been developed for LMV and STV by developing
colour in each case with, appropriate reagent. The analytically useful functional
groups in the drug have not been exploited completely in developing the new visible spectrophotometric method and so, the drugs have been selected in the present
investigation.
Different type of reagents like Gibbs reagent, MBTH reagent and BPB reagent
were used in the present investigation for developing visible spectrophotometric
methods. SUMMARY: Several drugs are available in the form of pharmaceutical formulations to
control diseases. Methods of assay for controlling the concentration of these
chemicals in the medicine and in the living body are necessary. Pharmaceutical
analysis occupies a pivotal role in statutory certification of drugs and their
formulations either by the industry or by the regulatory authorities. The complexity of
the problem encountered in pharmaceutical analysis coupled with importance of
achieving the selectivity, speed, cost, simplicity, precision and accuracy results in new
methods of analysis being quickly adopted by pharmaceutical industry.
Formulations containing combinations of drugs for potentiating or
complementing another in therapy are on the increase. In some cases, no precise
analytical methods are reported and quite often the reported procedures need
improvements or changes keeping in the view of the advances.
Among several instrumental techniques (HPLC, GC, Fluorimetry, NMR, mass
spectroscopy covering IR, UV and visible regions) available for assay of drugs,
visible spectrophotometric methods depend only on the nature of chemical reaction
utilized for colour development and not on sophistication of the equipment. GC
method is highly selective and sensitive compared to spectroscopic or other
chromatographic methods. GC method is also cost effective as expensive solvents are
not required and it is a versatile tool for qualitative and quantitative analysis of drugs
and pharmaceuticals.
Due to the importance of analysis, present analytical method has been
developed for some of the widely used antiretroviral drugs such as lamivudine, zidovudine, stavudine, nevirapine and efavirenz. Hence we planned o develop HPLC,
GC and spectrophotometric methods. CONCLUSION: Antiretroviral drugs are medications for the treatment of infection by retroviruses,
primarily HIV. When several such drugs, typically three or four, are taken in
combination, the approach is known as highly active antiretroviral therapy,
or HAART. The American National Institutes of Health and other organizations
recommend offering antiretroviral treatment to all patients with AIDS.
Although various UV-visible methods have been reported for the estimation of
LMV, ZDV and STV it was found that the reagents used in the present study were not
used and the methods developed are much sensitive and less time consuming
compared to the methods previously develop. The simultaneous estimation of LMV,
ZDV and EFZ with UV spectrophotometer using triple point method was not
investigated.
The work deals with four UV-Visible spectrophotometric methods i.e.
oxidation reaction with Cerium (IV) ammonium sulphate, visible spectrophotometric
method with BPB, GIBBS reagent and coupling reaction with MBTH reagent.
The methods are validated in terms of sensitivity, accuracy and precision.
A. Comparative Sensitivity
1> 2 > 3 > 4
B. Comparative accuracy:
3> 4 >2 > 1
C. Comparative precision:
3 > 4 > 1 > 2 Simultaneous estimation of LMV, ZVD and NVP by RP-HPLC was also
developed. The retention times of the drugs were less when compared to other
methods developed. In terms of sensitivity, accuracy and precision the present
developed method has shown good results when compared to the existing method.
Lamivudine was quantified by Gas Chromatographic method using Ethyl
Chloroformate as a Derivatizing reagent. There were no GC methods reported for
lamivudine. LMV analysis was performed after derivatization and the internal
standard technique was used for computation. The method development for the assay
of LMV was based on its chemical properties. The method developed is very sensitive
as the limit of detection is very less. Results of analysis of the pharmaceutical formulations revealed that the
proposed methods are suitable for their analysis with no interference from the usual
additives.
All the methods were found to be linear, precise, accurate, specific and all
proved to be sensitive, convenient and effective for the determination of LMV, ZVD,
STV, NVP and EFZ in bulk and pharmaceutical dosage forms