BIOCHEMICAL ANALYSIS OF HIPPURIC ACID AS A MARKER OF SOLVENT EXPOSURE AMONG SUBSTANCE USERS

Dr. Priyamvada Sharma*, Shraddha Hegde, Prof. Pratima Murthy and Prof. Vivek Benegal

ABSTRACT

Background: Inhalant sniffing offers fast and intense sensory experience to abusers which also contribute to its excessive use. Users can be an active user or have frequent exposure to solvents. Objective: A biochemical procedure for detection and quantification of hippuric acid as marker of solvent exposure (toluene, paint, thinner, eraser, inhalers) in urine is described and its effectiveness in clinical samples was also demonstrated. Methods: Simple chemical reaction for hippuric acid detection and quantification was improvised for clinical application, visual detection as well as quantification by wavelength reader was viable. Solvent exposures (intentional /occupational) among alcohol and drugs users were tested. Results: Hippuric acid levels were screened for 194 subjects, among them 46 had history of alcohol use, 33 were opiate users, 74 were cannabis user, 7 had history of poly substance use and 17 were benzodiazepine users. Fourteen subject with solvent use history and ten healthy volunteers also participated. Association between solvent contact and hippuric acid excretion was observed. Validation parameters for recovery ≥100%, accuracy 2.50, coefficient variance (r2), 0.998 were in acceptable range. Conclusion: Hippuric acid, a valid biomarker for solvent exposure has treatment implications also. Current study demonstrates its screening and quantification potential without being affected by diverse abuse patterns of user. This screening procedure for solvent exposure is cost and time effective and hold good sensitivity for further detection of other metabolites of solvent exposure in positive samples can be clubbed with other chromatographic techniques.

Keywords: Hippuric acid, Colorimeter, Enzyme Linked Immuno Sorbent Essay (ELISA), plate reader.