False-positive results of the determination of bacterial endotoxins in drugs: the use of a β-glucan blocker

Introduction. Assessment of the quality of drugs in terms of the indicator «Bacterial Endotoxins» has shown that along with the latter, β-glucans undergo enzymatic reaction with amebocyte lysate. This leads to false positive results in the (Limulus amebocyte lysate) LAL test, which poses a serious problem in the determination of pyrogenic impurities. There are 2 main sources of β-glucans in drugs: 1) excipients in the composition of a drug (for example, carmellose sodium, cross-linked sodium carboxymethylcellulose) and 2) technological impurities of the active ingredient at the drug production stage. Objective: to investigate the potentiating (reinforcing) effect of β-glucans in tests for bacterial endotoxins, to search and select a method for its elimination. Material and methods. The investigation objects were agents: Betamethasone, injectable suspension (7 mg/ml), and Inosine, injectable solution (20 mg/ml). Endotoxin-specific buffer (β-glucan blocker) was used to carry out the LAL test in gel-clot and chromogenic kinetic modifications. Results. The investigators considered the main causes of false results: potentiation (reinforcement) of a reaction of the LAL reagent with bacterial endotoxins due to the presence of β-glucans in the agents. Procedures were developed to eliminate the factors interfering with the LAL test in order to avoid false-positive results. Conclusion. Methodological approaches were elaborated to prevent the influence of a potentiating (reinforcing) interfering factor on the results of the LAL test