Molecular Mechanisms of Renal Cellular Nephrotoxicity due to Radiocontrast Media

Table 1

Iodinated contrast media commonly used in clinical practice.

Name	Type	Iodine content	Osmolality	Osmolality type
		(mg/mL)	(mOsm/kg)
Ionic
Diatrizoate (Hypaque 76)	Monomer	370	2,016	HOCM
Metrizoate (Isopaque 370)	Monomer	370	2,100	HOCM
Iothalamate (Conray 400)	Monomer	400	2,300	HOCM
Ioxaglate (Hexabrix)	Dimer	320	580	LOCM
Nonionic
Iopamidol (Isovue 370)	Monomer	370	796	LOCM
Iohexol (Omnipaque 350)	Monomer	350	884	LOCM
Iopromide (Ultravist 370)	Monomer	370	774	LOCM
Ioversol (Optiray 350)	Monomer	350	792	LOCM
Iomeprol (Iomeron 400)	Monomer	400	720	LOCM
Iobitridol (Xenetix 350)	Monomer	350	915	LOCM
Iodixanol (Visipaque 320)	Dimer	320	290	IOCM
Iotrolan (Isovist 300)	Dimer	300	320	IOCM

Ionic and nonionic contrast media may be monomeric or dimeric; 3 iodine atoms are present on each benzene ring of the contrast medium: if a contrast molecule contains only 1 benzene ring, it is called a monomer, if it contains 2 benzene rings, it is called a dimer. In solution, ionic contrast media break up into their anion and cation components, thereby increasing osmolality, while nonionic contrast media do not break up in solution. Nonionic dimers are the ideal contrast media as they deliver the most iodine with the least effect on osmolality.
The osmolality of contrast media is compared with the osmolality of plasma. HOCM (high-osmolar contrast media) have the highest osmolality, that is, 5–8 times the osmolality of plasma. LOCM (low-osmolar contrast media) have an osmolality still higher than plasma, which is, 2-3 times the osmolality of plasma. IOCM (iso-osmolar contrast media) have the same osmolality as plasma.