Decoding Xanthine Derivatives: Advanced Analytical, Extraction, and Quantification Techniques in Pharma and Biofluids...

Xanthine derivatives, such as bamifylline hydrochloride (BMFH), theophylline (THP), aminophylline (AMI), and diprophylline (DPH), are potent adenosine-receptor antagonists widely used in managing respiratory disorders like chronic obstructive pulmonary disease, asthma, and cardiac asthma due to their cardiovascular and diuretic properties. Despite their clinical utility, the complexity of their bioanalysis and limited advancements in analytical methodologies exhibit challenges to their broader application. This review evaluates advanced analytical, extraction, and quantification techniques for selected xanthine derivatives, emphasizing their applicability in pharmaceutical and biofluid matrices. A comprehensive review was conducted using databases like Scopus, PubMed, Web of Science, and ScienceDirect, utilizing keywords UV-visible spectrophotometric, chromatographic (high-performance liquid chromatography [HPLC], high-performance thin-layer chromatography [HPTLC]), and hyphenated (liquid chromatography-mass spectrometry [LC-MS]) techniques. A detailed analysis of extraction methods, including solid-phase extraction (SPE), liquid-liquid extraction (LLE), and protein precipitation (PPE), was included. The findings demonstrate that HPLC, often combined with SPE, offers superior sensitivity and specificity for quantifying xanthine derivatives. BMFH is effectively analyzed using HPLC with methanol (MeOH)-ammonium acetate mobile phases, achieving limits of detection <2 ng/mL. THP exhibits broad applicability in respiratory treatments, with UV-visible spectroscopy being widely used for its quantification. However, limited data for bioanalytical techniques, particularly for AMI and DPH, highlights the need for further development. Hyphenated techniques provide significant advantages in pharmacokinetic studies but remain underutilized for xanthines. This review refines analytical methods for xanthine derivatives to enhance their clinical and research applications. Future directions include developing high-throughput, automated techniques and expanding the bioanalytical profiling of underexplored derivatives like BMFH and AMI.