Detection of drugs of abuse: evolving analytical strategies and emerging challenges

The detection of drugs of abuse in biological and non-biological matrices remains a cornerstone of forensic, clinical, and public health investigations. Traditional matrices such as urine and blood provide short-term evidence of drug intake, while alternative specimens such as hair offer extended detection windows, and oral fluid provides a reliable indicator of recent drug intake comparable to blood. This review summarizes current knowledge on specimen selection, factors influencing drug absorption, distribution, and elimination, and highlights analytical strategies ranging from chromatographic and mass spectrometric methods to emerging electrochemical, optical, and biosensor platforms. Special emphasis is placed on the challenges posed by new psychoactive substances (NPS) such as synthetic cannabinoids (SCs), cathinones, hallucinogens, and amphetamine type stimulants, which continuously evolve to evade regulation and complicate detection. Advances in sample preparation, miniaturization, and portable analytical devices are critically evaluated in terms of sensitivity, specificity, and applicability to forensic and clinical settings. A central theme of this review is the two-tiered analytical framework that integrates rapid field screening technologies with highly selective chromatographic-mass spectrometric confirmation, providing a practical and scalable approach for addressing both conventional drugs of abuse and emerging NPS challenges.