Jelic-Ivanovic, Majkic-Singh, Spasic, Todorovic and 2ivanov-Stakic: Interference by drugs in common laboratory assays 287 J. Clin. Chem. Clin. Biochem. Vol. 23, 1985, pp. 287-292 Summary: Twenty five different analytical procedures, commonly used in clinical laboratories, were investigated for interference by eight analgesic and antirheumatic drugs. Ten of the investigated assays showed no statistically significant interference.