Fluspidine

Fluspidine
Clinical data
Other names	[18F]-Fluspidine
Identifiers
	IUPAC name 1'-benzyl-1-(2-(17F)fluoranylethyl)spiro[1H-2-benzofuran-3,4'-piperidine];
CAS Number	1355357-60-6;
PubChem CID	71719166;
ChemSpider	29397143;
ChEMBL	ChEMBL1939706;
Chemical and physical data
Formula	C21H24FNO
Molar mass	325.427 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES C1CN(CCC12C3=CC=CC=C3C(O2)CC[18F])CC4=CC=CC=C4;
	InChI InChI=InChI=1S/C21H24FNO/c22-13-10-20-18-8-4-5-9-19(18)21(24-20)11-14-23(15-12-21)16-17-6-2-1-3-7-17/h1-9,20H,10-16H2/i22-1; Key:LDFPQKADFLEDQV-KVTPGWOSSA-N;

Fluspidine is a fluorine-18 (¹⁸F) labeled radiotracer used in positron emission tomography (PET) scans to image σ₁ (sigma-1) receptors in the brain and other tissues. Sigma-1 receptors are proteins involved in many neurological and psychiatric processes. They have been linked to pain modulation, psychosis, Alzheimer's disease, and depression.^[1]

Chemical properties

Fluspidine is a small organic compound with a spirocyclic structure. A 2-fluoroethyl group on the molecule carries the fluorine-18. The compound exists as two mirror image enantiomers, called (R)-fluspidine and (S)-fluspidine. These enantiomers have slightly different properties: (R)-fluspidine has about 4-fold higher affinity for the σ₁ receptor than (S)-fluspidine, but (S)-fluspidine is metabolically more stable in the body.^[2]

References

^ Ludwig FA, Laurini E, Schmidt J, Pricl S, Deuther-Conrad W, Wünsch B (January 2024). "[¹⁸F]Fluspidine-A PET Tracer for Imaging of σ₁ Receptors in the Central Nervous System". Pharmaceuticals. 17 (2): 166. doi:10.3390/ph17020166. PMC 10892410. PMID 38399380.
^ Brust P, Deuther-Conrad W, Becker G, Patt M, Donat CK, Stittsworth S, et al. (October 2014). "Distinctive in vivo kinetics of the new σ1 receptor ligands (R)-(+)- and (S)-(-)-18F-fluspidine in porcine brain". Journal of Nuclear Medicine. 55 (10): 1730–1736. doi:10.2967/jnumed.114.137562. PMID 25071097.

[1] Ludwig FA, Laurini E, Schmidt J, Pricl S, Deuther-Conrad W, Wünsch B (January 2024). "[¹⁸F]Fluspidine-A PET Tracer for Imaging of σ₁ Receptors in the Central Nervous System". Pharmaceuticals. 17 (2): 166. doi:10.3390/ph17020166. PMC 10892410. PMID 38399380.

[2] Brust P, Deuther-Conrad W, Becker G, Patt M, Donat CK, Stittsworth S, et al. (October 2014). "Distinctive in vivo kinetics of the new σ1 receptor ligands (R)-(+)- and (S)-(-)-18F-fluspidine in porcine brain". Journal of Nuclear Medicine. 55 (10): 1730–1736. doi:10.2967/jnumed.114.137562. PMID 25071097.

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