Isonipecotic acid

Isonipecotic acid, also known as piperidine-4-carboxylic acid (P4C), is a conformationally constrained derivative of γ-aminobutyric acid (GABA) and a moderately potent GABA_A receptor partial agonist.^[1][2][3] It consists of a piperidine ring with a carboxylic acid moiety in the iso position.^[1] The drug showed moderate-efficacy partial agonism of α₁, α₂, α₃, and α₅ subunit-containing GABA_A receptors (E_maxTooltip maximal efficacy = 46–57%), but showed full or near-full agonism of α₄ and α₆ subunit-containing GABA_A receptors (E_max = 83–104%).^[2] Isonipecotic acid is unable to cross the blood–brain barrier.^[4] It was first described in the scientific literature by at least 1944^[5] and was identified as a GABA_A receptor agonist by 1978.^[6]

Isonipecotic acid

Clinical data
Other names	Piperidine-4-carboxylic acid; P4C; 4-Piperidinecarboxylic acid; Hexahydroisonicotinic acid; 4-Carboxypiperidine
Identifiers
IUPAC name piperidine-4-carboxylic acid
CAS Number	498-94-2 Y
PubChem CID	3773
IUPHAR/BPS	4227
ChemSpider	3641 Y
UNII	M5TZP1RWIE
ChEMBL	ChEMBL279998 Y
CompTox Dashboard (EPA)	DTXSID9060100
ECHA InfoCard	100.007.158
Chemical and physical data
Formula	C6H11NO2
Molar mass	129.159 g·mol−1
3D model (JSmol)	Interactive image
SMILES C1CNCCC1C(=O)O
InChI InChI=1S/C6H11NO2/c8-6(9)5-1-3-7-4-2-5/h5,7H,1-4H2,(H,8,9) N Key:SRJOCJYGOFTFLH-UHFFFAOYSA-N N
NY (what is this?)  (verify)

See also

• Piperidine-4-sulfonic acid (P4S)
• Isoguvacine
• Gaboxadol
• Muscimol
• Nipecotic acid