Alkoxyalkanoic acids

In contrast to the 2,4,6-triiodobenzoic acids, substituted alkanoic and alkoxyalkanoic acids containing a 2,4,6-triiodophenyl or a 2,4,6-triiodophenoxy group with open position 5, such as iopanoic acid, tyropanoate, iogly-camic acid, and iopronic acid, have both lipophilic and hydrophilic properties. These contrast acids have an acidity constant about two units higher than that of the water-soluble, fully substituted 2,4,6-triiodobenzoic acids (263) and are not completely ionized at the physiological pH. In the nonionized form, the contrast molecules can be absorbed and transported across cell membranes after oral administration. 

---