Biological Testing and Particle Sizing Flashcards
Particle sizing S.C
0.1-1um
Particle sizing filtered S.C
<0.1 - 0.22um
Particle sizing MAA
<150um
90% within 10-90um
How many particles recommended per dose
200k-600k/111-148 MBq dose
Particles per vial
5-8 million
When should particle # be decreased
- pediatrics
- Pulmonary hypertension
- R/L shunts
- pneumonectomy
QEII Dilute MAA instructions
- To cold MAA vial (A), add 2ml of saline. Avoid excess foaming.
- Withdraw 1.0 ml cold MAA from (A) using 21g needle and dispense in a sterile 10 ml vial (B).
- Add 4.2 GBq Tc99m eluate to 10 ml vial (B). Dilute so there is a total of 8ml with saline.
- Perform routine QC on vial (B).
- Particle count should be 10-20 particles / 200um square.
- Withdraw patient dose 148 MBq in 0.30 ml.
What are biological tests performed
○ Sterility
○ Apyrogenicity
○ Toxicity
Retrospective sterility
○ Conducted on randomly selected batches
○ Check the adequacy of aseptic technique
○ Conducted at regular intervals
■ Depending on historical results and trends
■ Complete more frequently when new personnel are added
Sterility definition
the absence of any viable bacteria or microorganismin the RP preparation
Autoclaving for sterilization
■ RP is heated with steam
■ 1210C @ 18 psi for 15 to 20 minutes
■ Good for thermostable aqueous solutions:
● 99m-Tc-pertechnetate
● 111-In-DTPA
● 67-Ga-Citrate
● 111-In-Chloride
■ Not good
● Short-lived RP
● 113m-In
● 18-F
● 99m-Tc-RP
Describe membrane filtration for sterilization
● Membrane Filtration
○ Filter RP through a membrane filter that removes various
organisms
○ Filter made of cellulose esters and available in various pore sizes
■ Common sizes:
● 0.45 microns
● 0.22 microns
● Method of choice for:
● Short-lived RP’s
● Heat-sensitive RP’s
the 2 methods for sterility testing
○ 1. Incubate RP in fluid thioglycollate medium (bacteria)
○ 2. Incubate RP in soybean-casein digest medium (fungi))
- 14 day incubation period
Pyrogens and symptoms of pyrogen administration
○ Polysaccharides or proteins, the
metabolic products of microorganisms
○ 0.05 – 1 um in size
○ Usually heat stable and soluble
Symptoms:
○ Fever, chills, flush, sweating
○ Leukopenia
○ Pain in joints, headache & dilation of
pupils
- symptoms appear within 45-90 minutes
- rarely fatal
- subside 10-12 hrs after onset
Pyrogen limits
● All injectable products should be pyrogen free or at least below the endotoxin limit
(EU)
○ For RP not given intrathecally: < 175 EU/V
○ Intrathecal injection: <14EU/V
■ V = per recommended dose in m
Apyrogenicity
● Sterilization does not guarantee apyrogenicity
○ Endotoxins not removed by sterilizing membrane filtration methods
THEREFORE a solution may be sterile but pyrogenic
○ Autoclaving does not destroy pyrogens completely
Common causes or sources of pyrogens
- impure solvents used in product prep
- impure glassware
what are the 2 pyrogen tests
- USP rabbit test
- LAL test
USP rabbit test
- give dose 3-10 x more than human dose
- inject into ear vein of rabbits
- temp taken 1, 2, and 3 hrs postinjection
- compare to baseline
- sterile saline is injected pre baseline as rabbits are subject to temp changes due to behavior
LAL test
○ From blood of the horseshoe crab
● The LAL gel test is simple to use.
○ Easier, rapid and more sophisticated (15-60 minutes)
○ Radiopharmaceutical is added to 0.1 ml of LAL and incubates at 37oC for 45 min
○ Invert the test tube and observe the reaction.
LAL test results
- If sample remains liquid: no endotoxins present
- if a sample forms a gel:endotoxins are present
Bacterial endotoxin testing
● BET for pyrogen is preferred over the rabbit test for RP preparations:
○ Simplicity
○ Sensitivity
○ Rapidity
○ Cost effectiveness
RP toxic effects
- alterations in histologial function of an organ or system
- alterations in a physiological function of an organ or system
- death
What causes toxicity
- Not usually due to the radionuclide
- the pharmaceutical usually is the issue, administered in portions too large
acute and chronic toxicity tests
● Tests for acute & chronic toxicity can be carried out on various animals
○ Mice, rabbits, dogs
○ Given RP for 2 to 6 weeks and sacrificed at various intervals
■ Autopsies performed to note any pathologic changes
LD 50/60
● Describes toxic effect of a RP
● Dose required to produce 50% mortality in 60 days
● Must be carried out in at least 2 species of animals
● Give doses to a large group and keep increasing dose until 50% are deceased
● In most RP’s toxicity is due to the pharmaceutical part not the radionuclide
● Since RP dose is so small most toxicity are carried on computer models and cell
cultures
NSHA sterility and pyrogen testing
▪ Performs retroactive sterility and pyrogen testing on 3 randomly selected
radiopharmaceuticals each month,
▪ Performs sterility testing (membrane filter) on 99m Tc SC (for reducing particle # in sentinel node imaging), and 99mTc ceretec prior to administration of
radiopharmaceutical
▪ Performs pyrogen testing on 99mTc DTPA for shunt imaging prior to
administration (typically takes 2 hrs for results)
▪ Nuclear medicine technologists dispense the samples and send them to the microbiology lab for testing
