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Ahmed Atwan

on 19 March 2014

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Transcript of C-11-Raclopride


Chemical Properties
Has capability of replacing cold carbon in biological molecules and have typical dynamics and kinetics in vivo
Organic chemistry
Pure β+ emitter
20.38 minutes Half-life (a double-sided sword)
Raclopride is a
selective dopamine receptor antagonist
with high affinity to
Used for imaging striatal dopaminergic receptors for assessing
Neuropsychiatric diseases (Schizophrenia and Parkinson’s disease)
Drug abuse
C-11 cyclotorn production
N(p,α) C
Production of Raclopride precursor
Labelling Step
Radionuclide form: C-11-MeI
Precursor form: Acid bromide
Solvents: DMSO, NaOH
Time and temp.: 3 minutes at 80℃
Yield: 50%
First way to label Raclopride
High Viscosity; inability to be automated
large amount of the precursor (2.3-2.5 mg)

Radionuclide form: C-11-MeI
Precursor form: Acid bromide
Solvents: DMF solution containing NaH trace
Time and temp.: 1-3 minutes at 120℃
25 minutes after EOB
Yield:11-14% S.A.: 33-91 GBq/μmol
Small amount of precursor (0.3-0.5mg) ,thus better HPLC separation
Not automated
Relatively low yield
Needs preheating

Radionuclide form: C-11-MeOTf
Precursor form: Free base
Solvents: Acetone and aqueous NaOH
Time 35 minutes EOB
temp.: Room temp.
Yield: 55-56%
S.A.: 56-74 GBq/μmol
Small amount of precursor (0.05-0.1 mg), thus better HPLC separation
Higher yield and S.A.
Not automated

Small amount of precursor
First automated method
Relatively low yield

Radionuclide form: C11-MeOTf
Precursor form: Desmethyl-raclopride triflate
Yield: 40% Decay corrected
S.A.: 33-91 GBq/μmol
Green Chemistry
Small amount of precursor
Higher yield and S.A.
98.2% radiochemical purity
Safety of operator
Facilitate production and maintenance processes
Further optimazation is needed to improve the yield
Radionuclide form: C-11-MeOTf
Precursor form:Desmethyl-raclopride TBA salt
Solvent: Butanone
Yield: 2.2% Non-decay corrected
S.A.: 308 TBq /μmol (8325 Ci/μmol)
Radionuclide form: C-11-MeOTf
Precursor form:Desmethyl-raclopride TBA salt
Solvent: Ethanol
Yield: 3.7% Non-decay corrected
S.A.: 770 TBq/mmol (20831 Ci/mmol)
The aim is to reach a reproducible method
Most promising
production scheme is the fully automated procedure using ethanolic solvents, due to
higher reaction yields
operator safety
deceased used of toxic solvents
1. Miller PW, Long NJ, Vilar R, Gee AD. Synthesis of C-11, F-18, O-15, and N-13 Radiolabels for Positron Emission Tomography. Angew Chem Int Edit. 2008;47(47):8998-9033.
2. Langer O, Nagren K, Dolle F, et al. Precursor synthesis and radiolabelling of the dopamine D-2 receptor ligand [C-11]raclopride from [C-11]methyl triflate. J Labelled Compd Rad. Dec 15 1999;42(12):1183-1193.
3. Iwata R, Pascali C, Bogni A, Miyake Y, Yanai K, Ido T. A simple loop method for the automated preparation of [C-11]raclopride from [C-11]methyl triflate. Appl Radiat Isotopes. Jul 2001;55(1):17-22.
4. Ishiwata K, Ishii S, Senda M. An alternative synthesis of [C-11]raclopride for routine use. Annals of nuclear medicine. Jun 1999;13(3):195-197.
5. Halldin C, Stoneelander S, Farde L, et al. Synthesis of C-11 Sch 23390, a Dopamine D-1 Receptor Antagonist, for Use in Invivo Receptor-Binding Studies with Pet. J Labelled Compd Rad. Oct-Dec 1986;23(10-12):1405-1406.
6. Link JM, Krohn KA, Clark JC. Production of [C-11]CH3I by single pass reaction of [C-11]CH4 with I-2. Nucl Med Biol. Jan 1997;24(1):93-97.
7. Larsen P, Ulin J, Dahlstrom K, Jensen M. Synthesis of [C-11]iodomethane by iodination of [C-11]methane. Appl Radiat Isotopes. Feb 1997;48(2):153-157.
8. Fei XS, Mock BH, DeGrado TR, et al. An improved synthesis of PET dopamine D-2 receptors radioligand [C-11]raclopride. Synthetic Commun. May 2004;34(10):1897-1907.
9. Wilson AA, Garcia A, Jin L, Houle S. Radiotracer synthesis from [(11)C]-iodomethane: a remarkably simple captive solvent method. Nucl Med Biol. Aug 2000;27(6):529-532.
10. Farde L, Hall H, Pauli S, Halldin C. Variability in D-2-Dopamine Receptor Density and Affinity - a Pet Study with [C-11] Raclopride in Man. Synapse. Jul 1995;20(3):200-208.
11. Kegeles LS, Martinez D, Kochan LD, et al. Mesolimbic and nigrostriatal ketamine-induced dopamine release measured by [C-11]raclopride PET in humans. J Nucl Med. May 2000;41(5):26p-27p.
12. Shao X, Hoareau R, Runkle AC, et al. Highlighting the versatility of the Tracerlab synthesis modules. Part 2: fully automated production of [11C]-labeled radiopharmaceuticals using a Tracerlab FXC-Pro. J Labelled Compd Rad. Dec 2011;54(14):819-838.
13. Gomez-Vallejo V, Llop J. Fully automated and reproducible radiosynthesis of high specific activity [C-11]raclopride and [C-11]Pittsburgh compound-B using the combination of two commercial synthesizers. Nucl Med Commun. Nov 2011;32(11):1011-1017.
14. Shao X, Schnau PL, Fawaz MV, Scott PJ. Enhanced radiosyntheses of [(1)(1)C]raclopride and [(1)(1)C]DASB using ethanolic loop chemistry. Nucl Med Biol. Jan 2013;40(1):109-116.

Thank You
Loop Method
Was first introduced using C-11-MeI then C-11-MeOTf
Full transcript