Radiopharmaceutical Production
QC Testing
Bacterial Endotoxins
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Bacterial Endotoxins
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All the pharmacopeia require that
radiopharmaceuticals intended for intravenous
administration must be tested to ensure that the
pyrogen concentration is within acceptable
limits.
Pyrogens most often originate from gramnegative bacterial cell walls – referred to as
bacterial endotoxin and that are readily detected
by a gel-clot or other techniques based on
Limulus amebocyte lysate (LAL).
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Contents
• Acceptance Criteria
• Discussion
• Example Procedure
Acceptance Criteria
Radiopharmaceutical
Production
QC Testing
Baterial Endotoxin
Contents
Acceptance Criteria
Discussion
Example Procedure
Acceptance Criteria: Not More Than 175 EU in the total
administered dose. The total administered dose is the maximum
administered volume at expiration stated in milliliters. This is
often written as 175EU/V. This test should be completed on
every batch. The batch may be released prior to completion of
the test but should the dose should not be injected into a patient
until the batch has passed this test.
Procedure: There are widely used and acceptable tests for
assessing presence of bacterial endotoxin in a
radiopharmaceutical preparation. One is the gel-clot technique
using Limulus Amebocyte Lysate (LAL). The bacterial endotoxin
test can also be performed with devices that utilize the turbidity
and kinetic measurement of gel formation. It is essential that the
test is validated for potential inhibition (and hence false negative
result) and positive controls.
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Discussion
Radiopharmaceutical
Production
QC Testing
Baterial Endotoxin
Contents
Acceptance Criteria
Discussion
Example Procedure
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Discussion: The gel-clot test entails typical incubation period of
60 minutes, which is much too long to wait for a 110 min half life
18F isotope. Consequently, product may be released for patient
use prior to completion of this 60 minute test. However, it is
possible to perform an ‘in-process’ LAL test with incubation
period of only 20 minute or less, and should be performed. In
addition to the gel-clot method, two other methods: turbidimetric
and kinetic are possible alternate that can be considered. A full
60 minute test may be performed at a specified time postrelease if required. It is recommended that the shorter version
LAL test is validated for its applicability. USP specifies that the
product can be distributed under control after the bacterial
endotoxin test is initiated. However, endotoxin test results
should meet the acceptance criteria before administrating the
product to humans.
The Chromogenic test is demonstrated here. This test is
complete in 20 minutes and gives a quantitative value for the
concentration of the endotoxins in the sample. This is very
useful for trending endotoxin levels.
Bacterial Endotoxins Procedure
Radiopharmaceutical
Production
QC Testing
Baterial Endotoxin
Contents
Acceptance Criteria
Discussion
Example Procedure
The 20 minute Endosafe PTS method
Methodology: The Endosafe PTS method involves a
prepared, pre-calibrated cartridge which is loaded with all
necessary reagents. The cartridge is inserted into the PTS
system, loaded with the radiotracer, and the test is
performed in less than 20 minutes. The tracer may need to
be diluted with buffer or LAL water. In general, for each
tracer, a 1:20 dilution is required.
Performing a Routine Test: Press the MENU key on the PTS
keypad to turn the unit on. The unit will perform a self test
and heat itself to 37 ºC. This will take approximately 5
minutes. The unit will display "SELF TEST OK" then
"INSERT CARTRIDGE.“ Remove a cartridge from its
packaging and insert it into the unit. The unit will heat the
cartridge to 37 ºC. Dispense the sample: With (4) separate
pipette tips, place 25 µL of sample into each of the four
wells. Press ENTER on the keypad to start the test.
Test Results: When the test is complete, the PTS reader
gives an audible signal and displays the results.
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