Iopanoic acid

Iopanoic acid is an inhibitor of 5'-Deiodinase and also an iodinated contrast medium.

Signaling Pathways >> Others >> Others

Research Areas >> Endocrinology

5'-Deiodinase[1]

The thyrotropin-releasing-hormone (TRH)-induced thyrotropin (TSH) release from the pituitary fragments is inhibited by 3,5,3'-triiodothyronin (T3) (10-7 M), by triiodothyroacetic acid (10-7 to 10-7 M), and by high concentrations of iodide (10-4 or 10-5 M). Iopanoic acid has no significant effect at the concentrations tested[2].

Iopanoic acid (IOP) administration to pregnant rats during days 18 and 19 postconception does not modify litter size (controls: 11.8±0.5 fetusesldam, Iopanoic acid-treated: 11.6±0.6 fetusesldam) or body weight at day 20 (controls: 3.27±0.12 g, Iopanoic acid-treated: 3.42±0.20 g). Iopanoic acid treatment produces a significant blockage of 5'-Deiodinase (5'D) activity in interscapular brown adipose tissue (IBAT) and brain; in contrast, liver 5'D is not modified. 3,5,3'-triiodothyronin (T3) content is similar in IBAT and slightly increased in brain and liver nuclei of Iopanoic acid-treated fetuses when compare with control fetuses at day 20 (p<0.05). However, when administered to adult rats, Iopanoic acid produces a significant reduction in IBAT nuclear T3 content and plasma T3 concentration. Iopanoic acid inhibition of IBAT 5'D activity in fetuses at term is as effective as at day 20[1].

Rat pituitary fragments are superfused by Medium-199. After a 90 min equilibration period, the superfusion is continued for 135 min with or without inclusion into the superfusion medium of 3,5,3'-triiodothyronin (T3) 10-7 M, triiodothyroacetic acid (TRIAC) (stock solution 10-4 M in 20% methanol, final concentrations 10-8 to 10-6 M), Iopanoic acid (stock solution 10-3 M in 0.2 M NaOH, final concentrations 10-7 to 10-5 M), or potassium iodide 10-7 to 10-4 M. The superfusion is followed by a 6-min pulse of thyrotropin-releasing-hormone (TRH)[2].

Wistar rats initially weighing 180 to 200 g are used. The administration of Iopanoic acid (IOP) is started at day 18 of gestation. Pregnant rats are injected subcutaneously with 10 mg of Iopanoic acid every 12 h, from day 18 of gestation to 12 h before they are killed on the morning of day 20 or 22 of gestation. Control animals receive the vehicle solution with identical timing. Iopanoic acid effectiveness in decreasing interscapular brown adipose tissue (IBAT) nuclear 3,5,3'-triiodothyronin (T3) is assessed by Iopanoic acid (IOP) administration to adult male rats (220 to 250 g body weight) following the same dose and time schedule as in pregnant dams during two days. Caesarean sections are performed at 18 (only untreated animals), 20 and 22 days of gestation. Fetuses are killed by decapitation, and IBAT, brain, and liver are removed. Tissue samples are immediately frozen in liquid nitrogen with the exception of brown fat from several 22 day-old fetuses, which is directly homogenized in 0.25 M sucrose for mitochondria isolation[1].

[1]. Tuca A, et al. 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]. Szabolcs I, et al. 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.

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DATA ITEMS CITED :

10

MOLECULAR FORMULA :

C11-H12-I3-N-O2

MOLECULAR WEIGHT :

570.94

WISWESSER LINE NOTATION :

ZR BI DI FI C1Y2&VQ

HEALTH HAZARD DATA

ACUTE TOXICITY DATA

TYPE OF TEST :

TDLo - Lowest published toxic dose

ROUTE OF EXPOSURE :

Oral

SPECIES OBSERVED :

Human - man

DOSE/DURATION :

86 mg/kg/1W-I

TOXIC EFFECTS :

Skin and Appendages - dermatitis, other (after systemic exposure)

REFERENCE :

ARDEAC Archives of Dermatology. (AMA, 535 N. Dearborn St., Chicago, IL 60610) V.82- 1960- Volume(issue)/page/year: 123,387,1987

TYPE OF TEST :

TDLo - Lowest published toxic dose

ROUTE OF EXPOSURE :

Oral

SPECIES OBSERVED :

Human - woman

DOSE/DURATION :

60 mg/kg

TOXIC EFFECTS :

Gastrointestinal - nausea or vomiting Blood - thrombocytopenia Skin and Appendages - dermatitis, other (after systemic exposure)

REFERENCE :

CTOXAO Clinical Toxicology. (New York, NY) V.1-18, 1968-81. For publisher information, see JTCTDW. Volume(issue)/page/year: 18,221,1981

TYPE OF TEST :

LD50 - Lethal dose, 50 percent kill

ROUTE OF EXPOSURE :

Oral

SPECIES OBSERVED :

Rodent - rat

DOSE/DURATION :

1540 mg/kg

TOXIC EFFECTS :

Behavioral - convulsions or effect on seizure threshold

REFERENCE :

TXAPA9 Toxicology and Applied Pharmacology. (Academic Press, Inc., 1 E. First St., Duluth, MN 55802) V.1- 1959- Volume(issue)/page/year: 14,232,1969

TYPE OF TEST :

LD50 - Lethal dose, 50 percent kill

ROUTE OF EXPOSURE :

Intraperitoneal

SPECIES OBSERVED :

Rodent - rat

DOSE/DURATION :

1520 mg/kg

TOXIC EFFECTS :

Details of toxic effects not reported other than lethal dose value

REFERENCE :

NIIRDN Drugs in Japan (Ethical Drugs). (Yakugyo Jiho Co., Ltd., Tokyo, Japan) Volume(issue)/page/year: -,103,1990

TYPE OF TEST :

LD50 - Lethal dose, 50 percent kill

ROUTE OF EXPOSURE :

Intravenous

SPECIES OBSERVED :

Rodent - rat

DOSE/DURATION :

280 mg/kg

TOXIC EFFECTS :

Behavioral - convulsions or effect on seizure threshold

REFERENCE :

TXAPA9 Toxicology and Applied Pharmacology. (Academic Press, Inc., 1 E. First St., Duluth, MN 55802) V.1- 1959- Volume(issue)/page/year: 14,232,1969

TYPE OF TEST :

LD50 - Lethal dose, 50 percent kill

ROUTE OF EXPOSURE :

Oral

SPECIES OBSERVED :

Rodent - mouse

DOSE/DURATION :

6600 mg/kg

TOXIC EFFECTS :

Details of toxic effects not reported other than lethal dose value

REFERENCE :

JMCMAR Journal of Medicinal Chemistry. (American Chemical Soc., Distribution Office Dept. 223, POB POB 57136, West End Stn., Washington, DC 20037) V.6- 1963- Volume(issue)/page/year: 13,997,1970

TYPE OF TEST :

LD50 - Lethal dose, 50 percent kill

ROUTE OF EXPOSURE :

Intraperitoneal

SPECIES OBSERVED :

Rodent - mouse

DOSE/DURATION :

1230 mg/kg

TOXIC EFFECTS :

Details of toxic effects not reported other than lethal dose value

REFERENCE :

NIIRDN Drugs in Japan (Ethical Drugs). (Yakugyo Jiho Co., Ltd., Tokyo, Japan) Volume(issue)/page/year: -,103,1990

TYPE OF TEST :

LD50 - Lethal dose, 50 percent kill

ROUTE OF EXPOSURE :

Intravenous

SPECIES OBSERVED :

Rodent - mouse

DOSE/DURATION :

320 mg/kg

TOXIC EFFECTS :

Details of toxic effects not reported other than lethal dose value

REFERENCE :

JMCMAR Journal of Medicinal Chemistry. (American Chemical Soc., Distribution Office Dept. 223, POB POB 57136, West End Stn., Washington, DC 20037) V.6- 1963- Volume(issue)/page/year: 13,997,1970 ** REPRODUCTIVE DATA **

TYPE OF TEST :

TDLo - Lowest published toxic dose

ROUTE OF EXPOSURE :

Oral

DOSE :

2200 mg/kg

SEX/DURATION :

female 1-22 day(s) after conception

TOXIC EFFECTS :

Reproductive - Effects on Newborn - growth statistics (e.g.%, reduced weight gain)

REFERENCE :

ATSUDG Archives of Toxicology, Supplement. (Springer-Verlag New York, Inc., Service Center, 44 Hartz Way, Secaucus, NJ 07094) No.1- 1978- Volume(issue)/page/year: 7,425,1984