lec 5- kit prep & overview of quality control

simplified order of kit prep- steps 1-3

1. elute generator- eluate (mCi/mL)

2. assay Mo-99 in eluate (μCi)

3. assay Tc-99m in eluate (mCi)

allowable limit during kit prep for Mo-99 and Tc-99m

Mo-99- 0.15μCi

Tc-99m- 1.0 mCi

simplified order of kit prep, steps 4-6

4. draw up amount of elution (i.e. Tc-99m) to equal total activity and measure it

5. add Tc-99m to kit

6. reaction time

some kits require ___ before adding Tc-99m to reaction vial

other steps, i.e. removal of gas

some kits require steps ___ preparation

after… i.e. heating, adding buffer

pH

measure of how acidic or aqueous a soln is

the ideal pH of a radiopharmaceutical should be ___

close to blood (which is 7.4). but can vary between 2-9 due to blood high buffer capacity

buffers are used to

adjust pH

some kits, like sulfur colloid, require pH to be adjusted when

preparing, in order to drive rxn to completion

compounding techniques

venting, heating, mixing, acids/buffers, rxn time (incubation), refrigeration

radiopharmaceuticals that use venting

MAG-3; comes w argon in kit, required a filter needle to be inserted to remove argon and add filtered air; air is added to oxidize excess stannous ion

radiopharmaceuticals that use heating

sulfur colloid- 5 min, cooled for 3

sestamibi- 10 min, cooled for 15

MAG-3- 10 min, cooled for 15

radiopharmaceuticals that use mixing

MDP, DTPA, Mebrofenin

radiopharmaceuticals that use acids/buffers

neurolite (req use of buffer soln), ultratag RBC labeling kit (req use of acid citrate dextrose ACD) to sequester residual extracellular stanous ion, allowing it to be available for oxidation

radiopharmaceuticals that use reaction time (incubation)

most kits are 15 min incubation

radiopharmaceuticals that use refrigeration

myoview (before prep), MAA (after prep)

use eluates that have in-growth times of no more than

24 hrs

avoid use of aged Tc-99m eluates; elution expires after

12 hours

avoid use of what type of saline?

bacteriostatic normal saline for prep or dilution of Tc-99m RPs

QC testing of RPs includes

radionuclidic purity, chemical purity, radiochemical purity, RP concerns

radionuclidic purity is

Mo99 to Tc99m ratio of eluate

chemical purity test is

alumina test of eluate

radiochemical purity is

labeled RPs

radiopharmaceutical concerns

particle size, sterility, pyrogenicity

when a Mo-99/Tc-99m generator is eluted, it’s possible to elute ___ along w the Tc-99m

aluminum

the aluminum contamination is derived from the alumina bed of the generator core

USP guidelines allow no more than ___ μg of aluminum ion per mL of ulate

10μg

a ___ test is used for aluminum ion

colorimetric test kit;

if <10μg/mL, will not turn as pink as standard color

what three Tc-99m species may be present after compounding

“Free Tc-99m present as 99mTcO4-,

hydrolyzed-reduced Tc-99m

“bound” Tc-99m

99mTcO4-

has not been reduced by Sn2+ and bound to drug; shows in salivary glands, stomach, thyroid

hydrolyzed-reduced Tc-99m

such as 99mTcO2 that didn’t react w chelating agent (drug)

shows up in liver, spleen

bound Tc-99m

chelate, which is desired compound formed by binding of reduced Tc-99m to the chelating agent

radiochromatography

instant thin layer chromatography (ITLC)- used to separate mixtures of substances into their components

order of radiochemical purity qc

1. place solvent into developing vial

2. spot RPs onto chromatography strip

3. develop strip in solvent

4. count strip using well detector/dose calibrator/radiochromatogram scanner

particle size QC for MAA

uses microscope and hemacytometer to view sizes

for MAA particle size qc, 90% of particles will be between what sizes

10-70μm

MAA particle sizes- none should be larger than

150 μm²