NRFPRESENTATIONNEWSAIP1finallypresentation13july

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Synthesis and Labeling of DISIDA (N-2,6-diisopropyl-phenylcarbamoylmethyliminodiacetic acid)

Musa Lonwabo Kwetana and Otto KnoesenNTP Radioisotopes (Pty) Ltd

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INTRODUCTION

•Radiopharmaceuticals are compounds labelled with a radioactive isotope that are used for studying different organs in the human body. Technetium-99m (99mTc) labelled iminodiacetic acid (IDA) derivatives are commonly used as hepatobiliary imaging agents; •Radiopharmaceuticals used for hepatobiliary imaging are divided into two groups based on thephysiologic function of the liver they are designed to evaluate;

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•One group is used to evaluate the functional status of the hepatocytes and patency of the biliary duct using cholescintigraphy, and the other group the phagocytic function of the Kupffer cell;

•Lipophilic compounds labelled with radionuclides evaluate the first, and labelled colloids evaluate the latter;

•The first iminodiacetic acid (IDA) derivative employed in nuclear medicine was 2,6-dimethylphenylcarbamoylmethyl iminodiacetic acid (HIDA). Of all IDA compounds, DISIDA and membrofenin are claimed to be the hepatobiliary agents of choice. The IDA agent of choice for NTP is DISIDA;

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•A cold kit is a pre-prepared vial containing DISIDA and stannous chloride dihydrate as the reducing agent. DISIDA kits are commercially available from NTP;

•The radioactive isotope of choice for IDA labelling is 99mTc;

•Labelling is accomplished by adding 99mTcO4- to the kit and mixing well.

Review of DISIDA Scan:

• A DISIDA scan is a test that looks at the flow of bile through your liver and gallbladder.

• This scan is done to check the function of your liver and gallbladder. This helps determined the location of possible gallstones, or if you have a blockage in the bile ducts that drain your liver.

• The material that allows us to see your liver and gallbladder contains a very small amount of radioactivity. This test will result in very low radiation.

• This test involves small amount of radioactivity into a vein in your arm. Your liver takes up the material and empties it into the bile ducts and then into the gallbladder.

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EXPERIMENTAL

Synthesis of DISIDA

Step 1: Synthesis of the 2,6-Diisopropyl-chloroacetanilide

2,6-Diisopropyl-chloroacetanilide is prepared by reacting 2,6-Diisopropylanaline with chloroacetylchloride in acetone according to scheme 1. The compound is isolated by addition of water;

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• Step 2: Synthesis of DISIDA

• 2,6-Diisopropyl-chloroacetanilide and disodium iminodiacetate is reacted in ethanol: water (3:1) according scheme 2. DISIDA is isolated by the adjustment of the pH to 2.

• Characterisation

• DISIDA is analysed by• • NMR• • Melting Point• • CHN analysis

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•Labelling and Quality Control of DISIDA

•Labelling is accomplished by adding 99mTcO4- to the kit and mixing well;

•Quality control is performed with Silicic acid impregnated instant thin layer chromatography paper (ITLC-SA and ITLC-SG) with 20% NaCl solution and 85 % methanol as mobile phase. The activity distribution is measured and recorded by a radiochromatogram scanner; The Rf values are given in Table 1

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Table 1. Rf values of 99mTc labelled DISIDA kits

Stationary phase

Mobile phase

Rf (99mTcO4-)

Rf(99mTc-DISIDA)

Rf(Hydrolyzed 99mTc)

ITLC-SA 20 % NaCl

1.0 0.0 0.0

ITLC-SG 85 % Methanol

0.0 1.0 0.0

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Biodistrubution of 99mTc-DISIDA

•The biodistribution DISIDA was confirmed by performing a biodistribution study on a Chacma baboon. Results are given in Figure 1.

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Scheme 1. Synthesis of 2, 6-Diisopropylanaline with chloroacetylchloride

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Scheme 2. Synthesis of DISIDA (N-2, 6-diisopropyl-phenylcarbamoylmethyliminodicetic acid).

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GOALS FOR THE PROJECT

•Study the synthesis of DISIDA;

•Improve the overall synthesis yield;

•Study the labelling and quality control of DISIDA with 99mTc.

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RESULTS

•The yield of the DISIDA synthesized was 66 - 76 gram (46 - 53%);

•The radiochemical purity of the labelled kits was > 95%;

•The experimental baboon study results are given in Figure 1 and conform to the standard biodistribution profile of DISIDA.

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CONCLUSION

•The yield of the DISIDA synthesis was improved from 26 – 34 g (18 – 24 %) to 66 - 76 g (46 - 53%);

•The labelling with 99mTc gave > 95% radiochemical purity;

•The improved synthesis resulted in increased cost effectiveness of the commercial DISIDA kits.

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Figure 1. Structural formula of the IDA-type and its coordinate to Tc (III).

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Figure 2. Biodistribution of DISIDA in a Baboon model. Images are at 1 minute intervals.

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Acknowledgement

•NRF/DST Internship 2009/2010 and registration for SAIP conference.

•Dr Otto Knoesen {NECSA(NTP)}

•WSU

•UP physics department even to give chance to study further whereas they did not want to pay for SAIP conference.

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REFERENCES

•Meitner L, Frisch OR (1939) Disintegration of uranium by neutrons: a new type of nuclear reaction Nature 143:239-240 [2]

•J.H. Burns, "Solvent-extraction complexes of the uranyl ion. 2. Crystal and molecular structures of catena-bis(.mu.-di-n-butyl phosphato-O,O')dioxouranium(VI) and bis(.mu.-di-n-butyl phosphato-O,O')bis[(nitrato)(tri-n-butylphosphine oxide)dioxouranium(VI)]", Inorganic Chemistry, 1983, 22, 1174-1178

•Decontamination of surfaces, George H. Goodalland Barry.E. Gillespie, United States Patent 4839100

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•For other work on the iodine chemistry which would occur during a bad accident, see [1][2][3]

•Glänneskog H (2004) Interactions of I2 and CH3I with reactive metals under BWR severe-accident conditions Nuclear Engineering and Design 227:323-9

•Glänneskog H (2005) Iodine chemistry under severe accident conditions in a nuclear power reactor, PhD thesis, Chalmers University of Technology, Sweden

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