Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Optical Properties of Meloxicam in the Far-Infrared Spectral Region



Yusuf S. Aytekin, Mustafa Koturk, Adam Zaczek, Timothy M. Korter, Edwin J. Heilweil, Okan Esenturk


One of the most commonly used nonsteroidal anti-inflammatory active pharmaceutical ingredient called Meloxicam has been characterized spectroscopically both by Terahertz (THz) time domain spectroscopy (THz-TDS) and by Fourier Transform Infrared (FTIR) spectroscopy in far-IR regions of electromagnetic spectrum; 0.2 THz to 20 THz. While many relatively sharp features are observed in the far-IR range between 2 THz to 20 THz as expected for being an organic substance, very distinct and relatively strong absorption bands are also observed at 1.00, 1.66, 2.07 and 2.57 THz in the THz range. These well separated, defined, and fairly strong spectral features can be used for discrimination and quantification of Meloxicam in drug analysis. Frequency dependent refractive index of the drug was determined in a range of 0.2 THz and 2.7 THz, where an almost constant index was observed with an average index of 1.75. Powder XRD, and solid state Density Function Theory (SS-DFT) calculations were utilized to determine the crystalline form of the Meloxicam sample in its enolic crystalline form. Single molecule DFT calculations were also performed in all four possible structures of Meloxicam. In addition, the capability of THz waves transmission through common packaging materials is demonstrated for possibility of future on-site analysis. The results suggest that drug analysis will be possible to perform not only at every stage of manufacturing without destruction but also directly at the shelf of a market after development of portable THz technologies.
Chemical Physics


THz-TDS, far infrared spectroscopy, active pharmaceutical ingredients (API), API characterization


Aytekin, Y. , Koturk, M. , Zaczek, A. , Korter, T. , Heilweil, E. and Esenturk, O. (2018), Optical Properties of Meloxicam in the Far-Infrared Spectral Region, Chemical Physics, [online], (Accessed April 15, 2024)
Created August 16, 2018, Updated October 12, 2021