Can a FT-IR Spectroscopy Method Offer Solvent-Free Testing for Common Blood Pressure Drug Combinations?

Researchers at Adichunchanagiri University in India have developed and validated a solvent-free analytical method for simultaneously measuring two widely prescribed cardiovascular drugs, amlodipine besylate (AML) and telmisartan (TEL), in pharmaceutical tablet formulations, according to a study published in Scientific Reports.¹

What are amlodipine besylate (AML) and telmisartan (TEL)?

Amlodipine (AML) and telmisartan (TEL) are commonly co-formulated to treat hypertension, making reliable simultaneous quantification a routine need for manufacturers and quality control laboratories.^1,2 AML is a calcium channel blocker, which means that it impacts how calcium moves through the body into the cells of the heart.² TEL works by blocking substances that tighten blood vessels to improve blood flow.²

What did the researchers do in their study?

In their study, the researchers used Fourier transform infrared (FT-IR) spectrophotometry and a pressed potassium bromide pellet technique to eliminate the need for organic solvents in routine quality control testing.¹ The approach represents a practical shift toward green analytical chemistry in pharmaceutical manufacturing and quality assurance workflows. The FT-IR method used in their study helped exploit distinct infrared (IR) absorption peaks for each compound (1,206 cm⁻¹ for AML and 863 cm⁻¹ for TEL) that do not overlap with each other or with the tablet matrix, enabling clean simultaneous analysis from a single scan.¹

How was method validation conducted in the study?

To validate their method, the researchers adhered to International Conference on Harmonization (ICH) guidelines. Using these guidelines, the researchers were able to show that their method demonstrated strong linearity across a concentration range of 0.20–1.20% w/w, with correlation coefficients above 0.998 for both compounds.¹ Recovery rates fell between 98.92% and 100.28%, meeting standard pharmaceutical acceptance criteria of 98–102%. Intra-day precision showed relative standard deviation below 2%.¹ The detection limits were 0.009 and 0.008% w/w for AML and TEL, respectively.¹

As part of their study, the researchers also compared their method against traditional green analytical chemistry assessment tools. Doing so allowed them to confirm its environmental profile, while statistical comparison showed no significant difference in performance versus HPLC.¹

According to the researchers, their method is suitable for routine analysis of both bulk drug substances and finished tablet dosage forms.¹

References

1. Prashant K, N.; Yenduri, S. Green Vibrational Spectroscopic Approach for Simultaneous Quantification of Antihypertensive Drugs in Bulk and Tablet Formulations. Sci. Rep. 2025, 15, 13097. DOI: 10.1038/s41598-025-97485-3
2. Mayo Clinic, Telmisartan and Amlodipine (Oral Route). Mayo Clinic. Available at: https://www.mayoclinic.org/drugs-supplements/telmisartan-and-amlodipine-oral-route/description/drg-20073274 (accessed 2026-05-20).