The possibility of replacing the rabbit pyrogen test by the Limulus Amebocyte
lysate (LAL) test, as a final release test for Large Volume Parenterals (LVPs)
was investigated. The sensitivity and specificity of the LAL test and rabbit
pyrogen assay were studied by means of artificially contaminated parenterals.
Various LVPs (mostly containing electrolytes) were spiked with 0.5 and 5 EUlml
of E.coli 01 11 :B4 endotoxin (Lambda =0.5 EUIml). The pH of the formulations
were measured, and if necessary, adjusted to 5.5 - 8.0 by NaOH or HC1. Four of
the products showed significant responses to the LAL test when the endotoxin
concentration was 0.1 nglml. However, the remaining formulations required
some degree of dilution prior to the test to overcome inhibition. The inhibitory
effect caused by cations on the LAL reaction is enhanced by increases in valency.
Therefore, the difference between the products in responding to the LAL test
have resulted from shifts in the electrokinetic potentials between the LAL
and the endotoxin. The rabbit test response was insignificant for all the
solutions. The LAL test was found to be useful for the detection of bacterial
endotoxin in LVPs. It also has the advantage of being more sensitive, rapid and
reproducible than the rabbit pyrogen test