Water-Soluble Iodine Contrast Agents -- Ionics Vs. Nonionics

Ionic compounds disassociate into charged particles in the bloodstream.

Nonionics do not break down into charged particles.

 

Ionic Contrast Media (High Osmolar Contrast Media - HOCM)

Here are some characteristics of ionic contrast agents:

A. They are positive agents

B. Affected anatomy is whiter (decreased density) compared to surrounding structures

C. Aqueous agents

–Water soluble

–Mixes readily with blood and bodily fluids

D. R2 and R3 increase solubility and excretion by kidneys

E. Iodine-based contrast media can cause anaphylaxis

 

 

Structure

1. Triiodinated compounds derived from the benzoic acid ring structure

     A. Benzene-a six carbon cyclic structure in which the double bonds rotate-C6H6

            (1) Carbonyl group - Carbon double bonded to oxygen-CO

          (2)  Carboxylic acid - A carbonyl and a hydroxyl (OH) combined on the same carbon atom - COOH

             (3)  The addition of carboxylic acid (COOH) to benzene forms benzoic acid

(4)  Salt - A compound containing a cation other than H+ and an anion other than -OH

2. The iodine or opacifying portion is located at parts 2, 4 and 6 of the ring

3.  The anion (negatively charged ion) is located at the 3 and 5 positions

     A. The three most commonly employed anions are diatrizoate, iothalomate and metrizoate

    B. Anions are responsible for stabilizing and detoxifying the contrast media

4.  The cation (positively charged ion), or salt, occupies the number 1 position

      A. The salts most commonly used are sodium and methylglucamine (meglumine)

            (1)  Meglumine is less toxic but more viscous than sodium

      B. Salts are responsible for the solubility of the medium

 

Examples:

1. Renocal-76

2. Reno-60

3. Cystografin-Dilute

4. Cystografin

5. Reno-30

6. Reno-Dip

7. Sinografin

8. Multihance

9. Feridex IV

10. Renografin-60

11. Optimark

12. Cholografin Meglumine

 

Concentration

1. The percentage of salts in the solution or the weight, in grams, of salts per 100 ml of solvent

      A. Renografin-60 has 8% sodium and 52% meglumine

      B.  Reno M-60 is 60% meglumine

 

Amount of Iodine

1. Stated in g/ml or mg/ml or as a percentage

A. Conray 400 has a 40% iodine content or 40 g/ml

     B.  Renografin 60 has 288 mg/ml or approximately 28% iodine content