ANALYTICAL TECHNIQUES FOR HYDROCHLOROTHIAZIDE AND TRIAMTERENE: DEVELOPMENT, GREENNESS-BY-DESIGN, AND FUTURE PROSPECTS

ABSTRACT
Background: Among several others, TRM and HCTZ stand as two of the most commonly
prescribed antihypertensive medicines. However, the quantitative determination of the same duo in
drug formulations remains challenging due to the common overlap in UV spectra in the region 200-
400 nm for both substances; hence, spectral analysis becomes difficult to achieve without some kind
of spectral separation process. Traditional techniques mostly revolved around the reversed-phase
HPLC technique, which was accurate but produced a high amount of organic solvent waste, which
became increasingly problematic with time due to stricter environmental regulations in the
pharmaceutical industry.
Objective: The current study attempts to explore the entire body of literature regarding analytical
techniques utilized for the quantitative determination of the TRM-HCTZ drug couple between 1989
and 2025 based on the following parameters: sensitivity in terms of LOD and LOQ, ICH Q2(R1)
validation requirement compliance, and environmental sustainability via AGREE, GAPI, BAGI, and
RGB Whiteness scales.
Methods: A comprehensive search strategy was employed for articles in PubMed, Scopus, Web of
Science, ScienceDirect, and Google Scholar using controlled terms alongside free text searches. Two
independent reviewers performed screening for all identified records. Data obtained from selected
studies were grouped into five categories based on the method used: derivative spectrophotometry,

HPLC/LC-MS/MS, multivariate calibration, continuous wavelet transform (CWT), and Greenness-
by-Design (GbD) methods that make use of MD and DFT simulations to determine analyte solvent

computationally.
Results: A total of 66 papers met all eligibility criteria. Derivative spectrophotometry showed LODs
of 0.17-1.02 μg/mL and recovery between 97%-103%. HPLC and LC-MS/MS provided much
higher sensitivity, with LOD values of 0.15 ng/mL, however, with significantly higher consumption
of organic solvents (50-200 mL of solvent per sample). Multivariate calibration and CWT methods
were able to overcome the problem of spectral overlapping by eliminating any need for the
separation step, yielding LODs of 0.09-0.32 μg/mL and correlation coefficients above 0.999. The
Greenness by Design (GbD) method that made use of MD simulations to select ethanol as the most
suitable solvent attained AGREE 0.81, BAGI 82.5, and RGB Whiteness 78, while decreasing the
solvent consumption by 80-90% compared to HPLC.
Conclusions: In the context of the pharmaceutical QC analysis, at the moment, the GbD-based
spectroscopy techniques are the most promising with respect to sensitivity, ICH compliance, and
minimized environmental impact. Further interlaboratory validation and inclusion in pharmacopoeia
represent the only two unresolved issues that need to be addressed.