Ortho-Iodohippuric acid

ortho-Iodohippuric acid

Clinical data
Other names	Iodohippuric acid, I Hippuran, I OIH, I-Hippuran, I-OIH, Iodobenzoylglycine, Sodium iodohippurate, Sodium o-iodohippurate, ortho' Iodohippurate, ortho-Iodohippurate, Orthoiodohippurate, Radio Hippuran, Radio-Hippuran, RadioHippuran, Sodium Iodohippurate [1]
Routes of administration	intravenous
Pharmacokinetic data
Excretion	renal
Identifiers
IUPAC name 2-[(2-Iodobenzoyl)amino]acetic acid
CAS Number	147-58-0
PubChem CID	8614
ChemSpider	8295
UNII	3Y68K91A3M
CompTox Dashboard (EPA)	DTXSID8046161
ECHA InfoCard	100.005.176
Chemical and physical data
Formula	C9H8INO3
Molar mass	305.071 g·mol^−1
3D model (JSmol)	Interactive image
SMILES C1=CC=C(C(=C1)C(=O)NCC(=O)O)I
InChI InChI=1S/C9H8INO3/c10-7-4-2-1-3-6(7)9(14)11-5-8(12)13/h1-4H,5H2,(H,11,14)(H,12,13) Key:CORFWQGVBFFZHF-UHFFFAOYSA-N

ortho-Iodohippuric acid (ortho-iodohippurate, OIH) is an analog of p-aminohippuric acid for the determination of effective renal plasma flow. Labelled OIH has a significantly higher clearance than other radiopharmaceutical yet developed and is eminently suitable for renography. It is eliminated mainly by tubular secretion. In patients with normally functioning kidneys, 85% of the OIH may be found in the urine 30 minutes after intravenous injection.

OIH was first labelled with ¹³¹I by Tubis and colleagues (Tubis, Posnick and Nordyke in 1960) and for many years this was the only radiopharmaceutical for renography. ¹³¹I has a half-life of 8 days and emits high-energy γ rays (364 keV) in addition to β particles. These physical characteristics were acceptable for probe studies when quantities of the order 1-2 MBq (25-50 μCi) were administered, but they are far from ideal for γ-camera studies which demand a higher activity and a γ ray emission of lower energy. The introduction of OIH labelled with ¹²³I, with its short physical half-life (13 hours) and its gamma emission of 159 keV has greatly improved the diagnostic potential of renal studies by combining the production of high-quality functional images with the ability to derive a renogram. The only factor limiting its widespread use is restricted availability and the expense involved in its cyclotron production.^[2]

References

1. Pubchem. "Compound Summary for CID 8614: 2-Iodohippuric acid". National Center for Biotechnology Information, U.S. National Library of Medicine.
2. Testa HJ (22 October 2013). "Radiopharmaceuticals". In O'Reilly PH, Shields RA, Testa HJ (eds.). Nuclear Medicine in Urology and Nephrology (2nd ed.). Butterworth-Heinemann. p. 239. ISBN 978-1483162416.