Iopanoate

Gall bladder Various oral cystographic agents, e.g., iopanoic acid Telepaque etc. Anion transport Urich K, Speck U (1991) Biliary excretion of contrast media. Progr Pharmacol Clin Pharmacol 8 307-322... 

Pancreas Oral cholecysto-graphic agent iopanoate ( ) experimental Unknown excretion into pancreatic duct Schmiedl U etal (1994) Imaging of exocrine pancreatic function investigation of the bioavailability of weak organic acids as potential pancreatic contrast agents for computed tomography. Invest Radiol 29 689-694... 

The use of LDL and other lipoproteins in drug targeting has been reviewed [170,172], Damle et al. [173] have shown that radiopharmaceuticals, such as iopanoic acid, a cholecystographic agent, could be incorporated in chylomicron remnants by esterification with cholesterol and used for liver imaging. About 87% of the chylomicron remnant-loaded iopanoic acid accumulated in the liver within 0.5 hour after administration, compared with 31% accumulated using a... 

Iopanoic acid 0.25 g Tetrabromo-phenolphthalein ethyl ester Each ml of 0.05 N AgN03 = 9.516 mg ofCuH12I3N02... 

Some of these triiodinated compounds are orally active, i.e. they are absorbed from the gastrointestinal tract after oral administration and imaging of the biliary system is possible following this route of administration. Examples are iopanoic acid, iophenoxic acid and sodium ipodate. A prerequisite for oral absorption is a balance of relatively hydrophilic and lipophilic moieties in the molecule. Numerous investigations have been performed to establish structure-activity relationships for this class of compounds, e.g. by Archer and Hoppe [70, 71]. Sodium salts are better absorbed than the free acids [72]. 

Weichert also synthesized sterol esters of triiodinated biliary contrast agents [83], such as cholesteryl, pregnenolone and dehydroepandrosterone iopanoate (Fig. 13). Only the first compound accumulated in the liver. The reason probably was its resistance to hydrolysis. 

Fig. 13. Chemical structures of cholesteryl iopanoate and glyceryl l,2,3-tris[3-(3-amino-2,4,6-triiodophenyl)]propionate [71]...

III.b.1.4. lodinated contrast media. When iodides or thioamides are contraindicated, the contrast media ipodate and iopanoic acid may be used to treat hyperthyroidism. These drugs rapidly inhibit conversion of T4 to T3 in the liver, kidney, brain and pituitary gland, and the effects are so rapid that they are sometimes helpful in the treatment of thyroid storm (see below). The drugs are non toxic and have prolonged effect. Precautions are similar to iodide,... 

Inhibition of 5 -deiodinase with decreased T3, increased rT3 Iopanoic acid, ipodate, amiodarone, blockers, corticosteroids, propylthiouracil, flavonoids... 

Many radiocontrast media contain iodine. These include iodixonal, iohexol, iomeprole, iopamidole, iopanoic acid, iopitridole, iopromide, iothalamate, iotrolan, ioversol, and ioxaglate. 

When five patients with type 2 amiodarone-induced hyperthyroidism were treated with a combination of an oral cholecystographic agent (sodium ipodate or sodium iopanoate, which are rich in iodine and potent inhibitors of 5 -deiodinase) plus a thionamide (propylthiouracil or methimazole) after amiodarone withdrawal, all improved substantially within a few days and became euthyroid or... 

In another study, three patients with type 1 disease, two of whom had not responded to methimazole plus perchlorate, were successfully treated with a short course of iopanoic acid 1 g/day, resulting in a marked reduction in the peripheral conversion of T4 to T3 (59). Euthyroidism was restored in 7-12 days, allowing uneventful thyroidectomy. The patients were then treated with levothyroxine for hypothyroidism and amiodarone was safely restarted. The authors suggested that iopanoic acid is the drug of choice for rapid restoration of normal thyroid function before thyroidectomy in patients with drug-resistant type... 

Iopanoic acid is as potent a uricosuric agent as probenecid and this effect might explain some renal complications aspirin reduces the uricosuric effect but can also impair X-ray visualization because of competition at plasma protein-binding sites. Fluctuations of serum urate after oral cholecystography can interfere with diagnostic tests and even precipitate an attack of gout (578). 

The effect of various surfactants, the cationics-eetyl trimethyl ammonium bromide (CTAB), and cetyl pyridinium chloride (CPC), the anionic-sodium lauryl sulfate (SLS), and the nonionic-polysorbate 80 (Tween 80), on the solubility and ionization constants of some sparingly soluble weak acids of pharmaceutical interest was studied (Gerakis et al., 1993). Benzoic acid (and its 3-methyl-, 3-nitro-, and 4-tert-butyl-derivatives), acetylsalicylic acid, naproxen, and iopanoic acid were chosen as model drugs. The cationics, CTAB and CPC, were found to considerably increase th< ionization constant of the weak acidS Ka ranged from-0.21 to-3.57), while the anionic, SLS, showed a negligible effect and the nonionic, Tween 80, generally decreased the ionization constants Solubility of the acids increased in aqueous micellar and in acidiLed micellar solutions. 

FIGURE 19.2 IDRs for form I (a), form II ( ), and amorphous ) iopanoic acid in pH 6.5 phosphate buffer at 37C. (Reproducedfrom Stagner, W.C. and Guillory, J.K. (I S. harm. Sci., 68 1005-1009. With permission from American Pharmaceutical Association.)... 

Stagner, WC. and Guillory, J.K. (1979). Physical characterization of solid iopanoic acid fbifttegrm. Sci., 68 1005-1009. 

Oral available as capsules and solution Iopanoic acid (Telepaque)... 

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