Extraction of Drugs and Metabolites from Biological Matrices

Extraction of drugs and their metabolites from biological matrices such as blood, plasma, urine, or tissues is a fundamental process in pharmaceutical, biomedical, and toxicological analysis, enabling accurate drug quantification, pharmacokinetic studies, and clinical monitoring. Biological samples contain a variety of interfering substances, including proteins, lipids, and salts, which can impede analytical detection and instrument efficiency. The extraction techniques serve to isolate analytes from these matrix components, thereby improving specificity, sensitivity, and reproducibility of results. Common extraction procedures include protein precipitation (removal of proteins using acids or solvents), liquid-liquid extraction (partitioning between immiscible solvents), and solid-phase extraction (adsorbent-based separation), along with advanced methods like solid-phase micro extraction and membrane-based approaches. These procedures often include concentration steps to enhance detection limits and sample clean-up to reduce damage to analytical instruments. Pre-treatment processes such as hydrolysis or homogenization may be necessary depending on sample type and analyte characteristics. Factors influencing extraction efficiency include pH, solvent polarity, temperature, and the physicochemical properties of the drug and its metabolites.