Iopanoic acid is an
iodine-containing
radiocontrast medium used in
cholecystography
Oral cholecystography is a radiological procedure used to visualize the gallbladder and biliary channels, developed in 1924 by American surgeons Evarts Ambrose Graham
Evarts Ambrose Graham (1883–1957) was an American academic, physician, and ...
. Both iopanoic acid and
ipodate sodium
Ipodate sodium (sodium iopodate) is an iodine-containing radiopaque contrast media used for X-rays. The drug is given orally and the resulting contrast allows for easy resolution of the bile duct and gall bladder.
Other uses
Although not FDA ...
are potent inhibitors of
thyroid hormone release from
thyroid gland, as well as of peripheral conversion of
thyroxine
File:Thyroid_system.svg, upright=1.5, The thyroid system of the thyroid hormones T3 and T4
rect 376 268 820 433 Thyroid-stimulating hormone
rect 411 200 849 266 Thyrotropin-releasing hormone
rect 297 168 502 200 Hypothalamus
rect 66 216 386 25 ...
(T
4) to
triiodothyronine
Triiodothyronine, also known as T3, is a thyroid hormone. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate.
Production of T3 and its prohormone thyroxine ...
(T
3). These compounds inhibit 5'deiodinase (5'DID-1 and 5'DID-2) enzymes, which catalyse T
4-T
3 conversion in the thyroid cell, liver, kidney, skeletal muscle, heart, brain, pituitary. This accounts for the dramatic improvement in both subjective and objective symptoms of
hyperthyroidism
Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidis ...
, particularly when they are used as an adjunctive therapy with
thioamide
A thioamide (rarely, thionamide, but also known as thiourylenes) is a functional group with the general structure R–CS–NR′R″, where R, R′, and R″ are organic groups. They are analogous to amides but they exhibit greater multiple bond ch ...
s (
propylthiouracil,
carbimazole
Carbimazole (brand names Neo-Mercazole, Anti-Thyrox, etc.) is used to treat hyperthyroidism. Carbimazole is a pro-drug as after absorption it is converted to the active form, methimazole. Methimazole prevents thyroid peroxidase enzyme from iodin ...
). They can be used in the treatment of patients with severe
thyrotoxicosis
Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. ...
(thyroid storm) and significant morbidity (e.g.,
myocardial infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may ...
, or stroke) for rapid control of elevated plasma triiodothyronine concentrations. The use of iopanoic acid for treatment of thyrotoxicosis has been discontinued in the United States.
In addition to inhibiting deiodinase enzymes, iopanoic acid is also a substrate of type 1 deiodinase. Iopanoic acid underwent monodeiodination in the presence of type 1 deiodinase in a microsomal mouse liver preparation.
References
Radiocontrast agents
Iodoarenes
Carboxylic acids
Anilines
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