Quantitation of polymorphic impurity in entecavir polymorphic mixtures using powder X-ray diffractometry and Raman...

Area of Science:

• Pharmaceutical Sciences
• Analytical Chemistry
• Materials Science

Background:

• Entecavir is crucial for treating chronic hepatitis B by inhibiting the hepatitis B virus.
• Anhydrous entecavir (ENT-A) can appear as an impurity polymorph during entecavir monohydrate (ENT-H) manufacturing.
• Controlling ENT-A content is vital as different crystal forms impact drug bioavailability and efficacy.

Purpose of the Study:

• To develop and validate quantitative methods for assessing ENT-A weight percentage in ENT-H.
• To establish reliable analytical techniques for impurity profiling in pharmaceutical manufacturing.
• To ensure the quality and therapeutic effectiveness of entecavir drug products.

Main Methods:

• Utilized Powder X-ray diffractometry (PXRD) and Raman spectroscopy to analyze binary mixtures of ENT-H and ENT-A.
• Constructed calibration curves using peak heights and areas versus weight percentage.
• Applied univariate and multivariate (Partial Least Squares - PLS) analyses to spectral data.

Main Results:

• Both PXRD and Raman methods demonstrated high linearity (R² > 0.9923) for ENT-A quantification within the 2.1-20.2% w/w range.
• Achieved low limits of detection (LOD) and quantitation (LOQ) for both methods (e.g., PXRD LOD: 0.38%, LOQ: 1.15%).
• PLS analysis showed excellent performance (R² = 0.9958, RMSEC = 0.44%, RMSEP = 0.65%), with Raman offering advantages in precision, accuracy, and time efficiency for industrial application.

Conclusions:

• Developed precise and accurate PXRD and Raman methods suitable for quantifying ENT-A in ENT-H.
• Raman spectroscopy is a promising method for industrial quality control of ENT-H due to its superior precision, accuracy, and speed.
• These validated methods support robust quality control for entecavir drug products, ensuring patient safety and therapeutic outcomes.