Thyroid-stimulating hormone (TSH) release from pituitary segments triggered by thyrotropin-releasing hormone (TRH) can be regulated by 3,5,3'-triiodothyronine (T3) (10-7 M), triiodothyronacetate (10 -7 to 10 -7 M), and high quantities of iodide (10-4 to 10-5 M). Iopanoic acid exhibited no meaningful effect at the concentrations examined [2].

Administration of iopanoic acid (IOP) to pregnant rats during days 18 and 19 after conception did not influence litter size (control: 11.8±0.5 fetusesldam, iopanoic acid-treated: 11.6±0.6 fetusesldam) or day 20 Body weight (control: 3.27±0.12) g, iopanoic acid treatment: 3.42±0.20g). Iopenic acid therapy significantly reduced 5'-deiodinase (5'D) activity in interscapular brown adipose tissue (IBAT) and brain; in contrast, hepatic 5'D was not affected. At day 20, iopanoic acid-treated fetuses showed equivalent 3,5,3'-triiodothyronine (T3) level in IBAT compared with control fetuses, and 3,5,3'-triiodothyronine (T3) in brain and liver cell nuclei. '-Triiodothyronine (T3) content increased somewhat (p<0.05). However, when provided to adult rats, iopanoic acid dramatically lowered IBAT nuclear T3 content and plasma T3 levels. Iopanoic acid suppresses IBAT 5'D activity in term fetuses as effectively as on day 20 [1].

Absorption, Distribution and Excretion
AFTER INGESTION, IT IS ABSORBED PROMPTLY, UNDERGOES CONJUGATION WITH GLUCURONIC ACID IN LIVER, IS CONCENTRATED & STORED IN GALLBLADDER, & IS ELIMINATED IN BILE.
FAILURE OF IOPANOIC ACID TO REACH DIAGNOSTIC CONCN IN BILE AFTER.../ORAL/ DOSES HAS BEEN SHOWN TO BE DUE, IN PART @ LEAST, TO IRREGULAR ABSORPTION. ABSORPTION OF.../ORAL/ DOSED IOPANOIC ACID IN DOGS WAS INCR IN PRESENCE OF BILE SALTS & SODIUM SALT FORM OF THIS AGENT IS ABSORBED MORE UNIFORMLY THAN FREE ACID.
BILIARY EXCRETION RATE OF SODIUM IOPANOATE FITTED BY COMPUTER TO MICHAELIS-MENTEN EQUATION AGAINST ITS UNBOUND PLASMA CONCN AVG MAX VALUE 0.85 MU MOLAR/KG/MIN, & KM VALUE 0.253 MU MOLAR. UNCHANGED IN MONKEY BLOOD & MAINLY NA IOPANOATE ESTER GLUCURONIDE IN BILE.
MAX EXCRETION OF IOPANOIC ACID INTO BILE OF UNANESTHETIZED DOGS WITH BILE FISTULA WAS CLOSELY CORRELATED TO EXCRETION RATE OF BILE SALTS.
For more Absorption, Distribution and Excretion (Complete) data for IOPANOIC ACID (6 total), please visit the HSDB record page.

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Metabolism / Metabolites
...IOPANOIC ACID...& TYROPANOIC ACID...IN DOGS & MAN...IDENTIFIED AS ESTER GLUCURONIDES. ... POORLY ABSORBED IN CATS... IOPANOIC ACID...PREVIOUSLY... FOUND...TRANSFORMED INTO...WATER-SOL CONJUGATE IN CATS & RE-EXAMINATION OF PROBLEM ESTABLISHED LIMITED GLUCURONIC ACID CONJUGATION OF IOPANOIC & TYROPANOIC ACIDS.

Interactions
RESULTS INDICATE THAT HEPATIC METABOLISM OF IOPANOATE TO ITS GLUCURONIDE IS DECREASED BY ETHER & PENTOBARBITAL ANESTHESIA IN COMPARISON TO URETHANE ANESTHESIA OR DECEREBRATION.
A SINGLE CASE HAS BEEN REPORTED OF POOR RADIOGRAPHIC VISUALIZATION OF THE GALL BLADDER DUE APPARENTLY TO AN INTERACTION BETWEEN IOPANOIC ACID AND CHOLESTYRAMINE WITHIN THE GUT.
IOPANOIC ACID ADMIN RESULTS IN INCR SULFOBROMOPHTHALEIN (BSP) RETENTION, PROBABLY BY COMPETING WITH BSP FOR CONCN AND EXCRETION BY THE LIVER.
STUDIES ON THE FACTORS THAT INFLUENCE THE INTESTINAL ABSORPTION OF CHOLECYSTOPAQUES REVEALED THAT CHOLESTYRAMINE DECREASED THE ABSORPTION OF IOPANOIC ACID. IOPANOIC ACID WAS ABSORBED RELATIVELY SLOWLY & EXCRETED AT A CONSTANT RATE.
IN HEALTHY SUBJECTS, TEMPORAL CHANGES IN THE RESPONSES OF SERUM TSH & PROLACTIN (PRL) TO A FIXED DOSE OF TRH (SYNTHETIC TSH-RELEASING HORMONE, 500 MUG, IV) WERE STUDIED & SERUM T4, T3, & RT3 CONCN WERE ASSESSED BEFORE, IMMEDIATELY AFTER, & THEN AT WEEKLY INTERVALS AFTER THE 3 DAILY DOSES OF IOPANOIC ACID. BOTH BASAL & TRH-STIMULTED TSH CONCN WERE INCREASED AT THE END OF THE PERIOD OF IP ADMIN. SERUM T3 CONCN WAS DECREASED.

[1]. Inhibition of iodothyronine 5'-deiodinase by iopanoic acid does not block nuclear T3 accumulation during rat fetal development. Pediatr Res. 1994 Jan;35(1):91-5.

[2]. Effects of triiodothyronine, triiodothyroacetic acid, iopanoic acid and iodide on the thyrotropin-releasing hormone-induced thyrotropin release from superfused rat pituitary fragments. Acta Endocrinol (Copenh). 1991 Oct;125(4):427-34.

Iopanoic acid is a monocarboxylic acid.
Iopanoic acid contains iodine and is useful as a contrast medium in cholecystography.
Radiopaque medium used as diagnostic aid.

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Mechanism of Action
.../IT/ SUPPRESSES THYROID FUNCTION IN EUTHYROID AND HYPERTHYROID INDIVIDUALS.
TSH INDUCED SECRETION OF 3,3'-DIIODOTHYRONINE, 3',5'-T2, & 3,5-T2 BY PERFUSED DOG THYROID WAS DETERMINED. IOPANOATE (10-5 MOLAR) & IPODATE (10-5 MOLAR), BOTH INHIBITORS OF PERIPHERAL IODOTHYRONINE DEIODINATION, INHIBITED 3,3'-DIIODOTHYRONINE SECRETION.
THE ABILITY OF ROENTGENOGRAPHIC CONTRAST AGENTS TO INHIBIT BINDING OF (125)I-LABELED T3 TO NUCLEAR RECEPTORS WAS STUDIED DURING INCUBATION OF RAT LIVER NUCLEI OR NUCLEAR EXTRACTS IN VITRO & AFTER IP ADMIN OF THE AGENTS IN VIVO. IOPANOIC ACID INHIBITED BINDING OF T3-(125)I IN VITRO.
CHANGES IN CONCN OF TSH, THYROXINE, T3, & REVERSE T3 IN SERUM WERE EXAMINED IN 21 MALE EUTHYROID SUBJECTS AFTER ORAL ADMIN OF 3 G/DAY OF IOPANOIC ACID. CONCN OF TSH, THYROXINE, & REVERSE T3 INCREASED, WHEREAS CONCN OF T3 DECREASED AFTER ADMIN OF IOPANOIC ACID.

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Therapeutic Uses
Contrast Media
ORALLY AS A RADIOPAQUE MEDIUM IN CHOLECYSTOGRAPHY. ALTHOUGH NOT THE METHOD OF CHOICE, IT MAY ALSO BE USED FOR ORAL CHOLANGIOGRAPHY.
USUAL REGIMEN IS TO GIVE PT FAT-FREE EVENING MEAL FOLLOWING WHICH IOPANOIC ACID IS ADMIN APPROX 10 HR BEFORE TIME SCHEDULED FOR ROENTGENOGRAPHY. IMMEDIATELY AFTER ROENTGEN EXAM, PT IS GIVEN HIGH-FAT MEAL & ADDITIONAL EXPOSURES ARE MADE...TO EVALUATE CONTRACTION OF GALL BLADDER & TO VISUALIZE PATENCY OF EXTRAHEPATIC DUCTS. WHEN LATTER STRUCTURES ARE OF PARTICULAR INTEREST, DOSE OF IOPANOIC ACID MAY BE INCR TO 5 OR 6 G. DOSE--3 TO 6 G; USUAL, 3 G.
TYROPANOATE 3 G, IOCETAMIC ACID 4.5 G, IOPANOIC ACID 3 G & IOCETAMIC ACID 3 G, WERE EVALUATED IN 800 PT. IOCETAMIC ACID IS AS RELIABLE & EFFECTIVE AS TYROPANOATE OR IOPANOIC ACID IN CHOLECYSTOGRAPHY. 3 G DOSE PRODUCES CHOLECYSTOGRAMS AS SATISFACTORY AS 4.5 G WITH LOWER INCIDENCE OF CRAMPS.

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Drug Warnings
IT IS CONTRAINDICATED IN PT WITH ACUTE NEPHRITIS AND UREMIA, SINCE IT IS ELIMINATED BY THE KIDNEYS. IT SHOULD NOT BE ADMIN WHEN DISORDERS OF THE GI TRACT EXIST WHICH PREVENT ABSORPTION OF THE MEDIUM.
IOPANOIC ACID APPEARS TO COMPETE WITH BILIRUBIN FOR HEPATIC UPTAKE, RESULTING IN TRANSIENT ELEVATIONS OF SERUM BILIRUBIN.
CONTRAST NEPHROPATHY IS AN ADVERSE ALTERATION IN RENAL FUNCTION INDUCED BY INTRAVASCULAR CONTRAST MEDIA. THE INCIDENCE OF CONTRAST NEPHROPATHY IN THE GENERAL HOSPITALIZED POPULATION IS ABOUT 5%, & IS ASSOCIATED WITH PREEXISTING RENAL INSUFFICIENCY & DIABETES MELLITUS. AS MANY AS TWO-THIRDS OF PATIENTS WITH CHRONIC RENAL FAILURE MAY EXPERIENCE AN ACUTE DETERIORATION IN RENAL FUNCTION FOLLOWING EXPOSURE. DIABETIC PATIENTS WITH PREEXISTING RENAL INSUFFICIENCY ARE AT AN EVEN GREATER RISK; ABOUT 75% OF SUCH PATIENTS WILL EXPERIENCE RENAL COMPLICATIONS. IN MULTIPLE MYELOMA THE RISK OF CONTRAST-INDUCED RENAL FAILURE IS LOW, & PROBABLY INVOLVES A DIFFERENT PATHOGENESIS THAN SEEN IN OTHER CASES OF CONTRAST NEPHROPATHY. PERIPHERAL VASCULAR DISEASE, HYPERTENSION, OLD AGE & LARGE & REPEATED DOSES OF CONTRAST MAY INCREASE THE RISK IN SUSCEPTIBLE PATIENTS.

C11H12I3NO2

570.9354

570.8

96-83-3

3735

POWDER

2.426g/cm3

529.1ºC at 760mmHg

153 °C

273.8ºC

1.732

4.317

2

3

4

17

277

0

O=C(C(CC)CC1C(I)=C(N)C(I)=CC=1I)O

OIRFJRBSRORBCM-UHFFFAOYSA-N

InChI=1S/C11H12I3NO2/c1-2-5(11(16)17)3-6-7(12)4-8(13)10(15)9(6)14/h4-5H,2-3,15H2,1H3,(H,16,17)

2-[(3-amino-2,4,6-triiodophenyl)methyl]butanoic acid

BRN 2220381; Telepaque; Iopanoic Acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~100 mg/mL (~175.15 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (4.38 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (4.38 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (4.38 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)