Background: Apranax Plus® is a new bilayer tablet dosage form, which combines two active
pharmaceutical ingredients: naproxen sodium and codeine phosphate.
Objective: The purpose of this work was to develop an Ultra-High-Performance Liquid Chromatography
(UHPLC) method for the separation and determination of codeine phosphate hemihydrate impurities
in a bilayer tablet dosage form.
Methods: The separation and determination of codeine phosphate hemihydrate and its impurities,
methylcodeine, morphine, codeine dimer, 10-hydroxycodeine, 14-hydroxycodeine, thebaine and codeinone
were achieved by using reversed-phase liquid chromatography with TUV (Tunable UV Detector)
and PDA (Photodiode Array Detector) detection by UHPLC. The new proposed method utilized by
the Waters Acquity UHPLC® TUV and PDA systems using a UHPLC column Waters Acquity, BEH,
C18, 2.1x100 mm, 1.7 μm particle size with a mixture of component A and acetonitrile in a gradient
mode at a flow rate of 0.3 mL/min, at 25°C with a load of 5μL. The detection for all eluted compounds
was carried out at 245 nm.
Results: The codeine phosphate hemihydrate and peaks of its impurities were adequately obtained, thus
proving the stability-indicating power of the method. The developed method was validated as per the
ICH guidelines with respect to parameters such as precision, accuracy, linearity, Limit of Detection
(LOD), Limit of Quantification (LOQ) and robustness.
Conclusion: It was verified as being adequate for all the mentioned impurities of codeine phosphate
hemihydrate. The described method was found to be useful for routine purity testing and was also found
suitable for the analysis of the stability samples of the drug product.