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At least 19 recordsLinked to original sources
PubMed1991

Effects of triiodothyronine, triiodothyroacetic acid, iopanoic acid and iodide on the thyrotropin-releasing hormone-induced thyrotropin release from superfused rat pituitary fragments.

The effects of triiodothyronine, triiodothyroacetic acid, iopanoic acid and potassium iodide were investigated on basal and stimulated thyrotropin release in an in vitro experimental model. Rat pituitary fragments were superfused by Medium-199 with or without T3 (10(-7) mol/l), triiodothyroacetic acid (10(-8)-10(-6) mol/l), iopanoic acid (10(-7)-10(-5) mol/l) or potassium iodide (10(-7)-10(-4) mol/l). This was followed by a 6-min pulse of thyrotropin-releasing hormone (10(-8) mol/l). TSH was measured in 3-min fractions. The TRH-induced TSH release from the pituitary fragments was inhibited by T3 (10(-7) mol/l), by triiodothyroacetic acid (10(-7)-10(-6) mol/l), and by high concentrations of iodide (10(-4) or 10(-5) mol/l). Iopanoic acid had no significant effect at the concentrations tested. It is assumed that in vitro, and at similar concentrations, the inhibitory effect of triiodothyroacetic acid on the TRH-induced TSH secretion is comparable to that of T3, whereas iopanoic acid may have no direct detectable effect. In contrast, a direct inhibitory effect of inorganic iodide, at least in pharmacological concentrations in vivo, cannot be excluded.

Animals↗
PubMed1976

The interactions between iophenoxic acid, iopanoic acid, bilirubin and human serum albumin as studied by fluorescence and Sephadex gel filtration.

Iophenoxic acid increases the fluorescence of bilirubin bound to human serum albumin at drug/albumin molar ratios lower than 1, while iopanoic acid decreases it. The fluorescence enhancement results probably from a change in the fluorescence efficiency due to an iophenoxic acid-induced conformational change in the albumin, which in turn causes displacement of bilirubin from the protein. Iophenoxic acid does not affect the high-affinity bilirubin binding site of albumin. Therefore any enhancement in bilirubin fluorescence caused by the drug indicates that bilirubin is bound to the low-affinity binding sites of albumin. The use of iophenoxic acid in the determination of the extent of saturation of the high-affinity bilirubin binding site of albumin may be of value in the clinical management of infants with neonatal jaundice.

Bilirubin↗
PubMedDate not supplied

Pituitary thyrotroph hypofunction in aged euthyroid subjects as assayed by the administration of iopanoic acid.

Iopanoic acid, an iodine containing contrast medium was administered orally to healthy subjects aged 20-40 years (n = 9) and 70-90 years (n = 10) and also to sick aged persons (aged 70-90 years, n = 10). Thyroid hormones: T4, T3, rT3, T3-uptake and thyrotropin (TSH) serum levels were estimated before and three and seven days after iopanoic acid. No significant TSH increase could be seen in the old-age groups: the T4 increases were similar in all three groups as well as the slight T3 decreases; the serum rT3 increase was significantly greater in the aged healthy and the sick subjects. The data suggests that in aged humans serum T4 elevation after iopanoic acid is a result of delayed thyroxine metabolism and not secondary to TSH release. Iopanoic acid administration is, aside from the TRH test, another model to demonstrate in geriatric patients thyrotroph hypofunction via the altered effect of inhibition of T4 deiodination on TSH release.

Adult↗
PubMed1979

Kinetics of drug-drug interactions: biliary excretion of iodoxamic acid and iopanoic acid in rhesus monkeys.

The dynamic method originally developed for studying the capacity-limited kinetics of the cholecystographic agents iodoxamic acid and iopanoic acid was applied to study the in vivo interactions of these two compounds following coadminstration in the monkey. Results indicate that these interactions are complex. The compounds appear to compete for plasma protein binding sites as well as for binding sites on intrahepatic proteins. The biliary excretion data apparently fit the "ligand exclusion" model in which iopanoic acid acts as an inhibitor and competes with iodoxamic acid for binding to either of two identical sites within the liver. This competition probably is the rate-limiting step in the liver's overall elimination of these radiographic contrast agents.

Animals↗
PubMed1980

Comparison of oral cholecystopaques: iopronic acid vs. iopanoic acid.

A new oral cholecystopaque, iopronic acid, was compared to iopanoic acid. This was a double blind, randomized study of 260 subjects. A 4.5-G dose of iopronic acid produced a similar degree of gallbladder opacification as 3.0 g of iopanoic acid. Adverse reactions to the contrast media were generally mild, but were significantly less with iopronic acid. The present study is criticized because it was not designed to help the radiologist determine the better contrast medium under optimal clinical conditions.

Cholecystography↗
PubMed1979

Effects of three-day oral cholecystography on serum iodothyronines and TSH concentrations: comparison of the effects among some cholecystographic agents and the effects of iopanoic acid on the pituitary-thyroid axis.

The effects of repeated doses of oral cholecystographic agents on serum thyroxine (T4), 3,3',5-triiodothyronine (T3), 3,3',5'-triiodothyronine (rT3) and thyrotrophin (TSH) concentrations were studied in 37 euthyroid male subjects. Iobenzamic acid, tyropanoic acid, iopanoic acid, and ipodate sodium, in a dosage of 3 g for 3 days, respectively, induced a significant decrease in serum T3 and an increase in rT3 within 24 h after the initial dose, followed by an increase in TSH and a slight increase in T4. The extent of the changes in rT3 varied between the agents, ipodate causing the greatest change, but without any relation to the changes in T3 or T4. Responses of serum T4, T3, rT3 and TSH concentrations to exogenous thyrotrophin-releasing hormone (TRH) and bovine TSH were also studied before and after 3-day doses of iopanoic acid. In 11 subjects given iopanoic acid, the response to TSH to TRH (500 micrograms, iv) was increased but the T3 response was unchanged. A dose of TSH (10 U.S.P. units, im) caused a significant increase in serum T3 and a decrease in TSH concentrations in 5 subjects both before and after cholecystography. It is thus suggested that in euthyroid subjects given multiple doses of oral cholecystographic agents, (1) the primary and consistent events are the reciprocal changes of serum T3 and RT3, although the extent of the changes is not coordinately reciprocal; (2) the responsiveness of the pituitary thyrotrophs and thyroid to TRH is preserved; and (3) the high basal and TRH-induced TSH in the serum may be ascribed to the decrease in the serum T3 concentration.

Administration, Oral↗
PubMed1979

A comparative trial of two oral cholecystographic contrast media--iocetamic acid (Cholebrin) and iopanoic acid (Telepaque).

A comparative trial was made between two oral cholecystographic agents, iocetamic acid (Cholebrin) and iopanoic acid (Telepaque), Fifty patients were given Cholebrin and another 50 were given Telepaque by random allocation. The cholecystographic qualities of the two contrast media showed no significant difference. It was noted that contrast medium within the bowel at the time of the investigation tended to be homogeneous rather than granular with Cholebrin, and the significance of this is discussed. Gastrointestinal side-effects were common with both contrast media, but there was a significantly lower incidence of diarrhoea with Cholebrin than with Telepaque. Various biochemical parameters of hepatic and renal function were measrued in 40 random patients and showed no clinically significant alteration following ingestion of the contrast media.

Administration, Oral↗
PubMedDate not supplied

Saturation kinetics of iocetamic acid: Evaluation of indirect pharmacokinetic techniques and comparison with iopanoic acid.

The biliary excretion of two oral cholecystographic contrast agents, iocetamic acid and iopanoic acid, were compared during low and high taurocholate infusion rates. The pharmacokinetics of these compounds after intravenous infusion were studied in bile-fistula dogs using both indirect and direct pharmacokinetic techniques. The indirect multiple infusion technique, corrected for urinary excretion, provides a reliable estimate of the maximum biliary excretion rates of either contrast agent without necessitating the sampling of biliary output. The results indicate that taurocholate facilitates the biliary excretion of both agents. At both taurocholate infusion rates studied, the maximum biliary excretion rate of iocetamic acid is greater than that of iopanoic acid.

Animals↗
PubMed1985

Inhibitory effect of iopanoic acid on the thyrotropin-stimulated release of cyclic adenosine 3',5'-monophosphate and of 3,5,3'-triiodothyronine from perifused rat thyroids.

Using a perifusion system, we studied the effect of iopanoic acid, an iodinated contrast agent used in oral cholecystography, on the release of cAMP, T3, T4, and rT3 from perifused rat thyroid pieces. A 0.1 mg/ml iopanoic acid solution significantly inhibited the TSH-stimulated release of cAMP (without iopanoic acid, 8175 +/- 373; with iopanoic acid, 5169 +/- 355 fmol/mg thyroid X 3 h, mean +/- SE) and T3 (without iopanoic acid, 971 +/- 32; with iopanoic acid, 659 +/- 32 pg/mg thyroid X 3 h) in the presence of 3-isobutyl-1-methylxanthine. T4 and rT3 releases were not significantly affected. Inhibition of TSH-stimulated T3 release by iopanoic acid was also observed at a concentration of 0.01 mg/ml. Propylthiouracil completely abolished the inhibitory effect of iopanoic acid on TSH-stimulated cAMP release but not on TSH-stimulated T3 release. TSH-stimulated cAMP release was augmented by iodide at a concentration of 1 X 10(-3) M in the presence of 3-isobutyl-1-methylxanthine but suppressed by iodide at a concentration of 1 X 10(-5) M. TSH-stimulated T3 release was suppressed slightly at both concentrations of iodide. These results suggest that iopanoic acid may have an inhibitory effect on the TSH-stimulated cAMP and T3 release from perifused rat thyroids. This effect can probably be attributed to the iodide contained in the agent and to the inhibited intrathyroidal conversion of T4 to T3.

1-Methyl-3-isobutylxanthine↗
PubMedDate not supplied

Clinical comparison of two contrast agents for oral cholecystography: radiologic efficacy and drug safety of iopanoic acid and iopronic acid.

Oral doses of either iopronic acid (4.5 g Oravue, Squibb) or iopanoic acid (3 g Telepaque, Winthrop) were given to 98 patients requiring cholecystography. Radiographs were taken 13 to 16 hours after treatment showed good to excellent gallbladder opacification in 44 percent of patients after the first dose of iopronic acid and in an additional 29 percent after a second dose. Similar opacification occurred in 42 percent of patients after the first dose of iopanoic acid and in 34 percent after a second dose. Drug-related abnormalities in blood and urine tests occurred about equally in both groups and one patient in each group exhibited a clinically adverse reaction (diarrhea). Thus, the performance (radiographic efficacy and drug safety) of the new contrast agent, iopronic acid, was similar to a widely used drug, iopanoic acid.

Administration, Oral↗
PubMed1982

Potential tumor- or organ-imaging agents. 23. Sterol esters of iopanoic acid.

A series of sterol esters of iopanoic acid was synthesized and evaluated for their potential to selectively localize in liver and steroid-secreting tissues for possible application in either computed tomography or nuclear medicine imaging. Unlike free iopanoic acid (1), which was rapidly cleared following intravenous administration to rats, cholesteryl iopanoate (2) was found to accumulate in liver, adrenal cortex, and ovary. At 24 h, the ovary was found to contain the highest concentration of 2. The ability of 2 to accumulate in the above tissues was attributed to its resistance to hydrolysis. Pregnenolone iopanoate (3) and dehydroepiandrosterone iopanoate (4), on the other hand, were shown to reach unusually high concentrations in the adrenal cortex within 0.5 h of administration but declined to much lower levels by 24 h. Lipid extraction of tissues showed 3 and 4 to be susceptible to in vivo hydrolysis, which undoubtedly was a major factor in their clearance from adrenal tissue.

Animals↗
PubMed2004

Iopanoic acid in the management of neonatal Graves' disease.

OBJECTIVE: Traditionally, neonatal thyrotoxicosis has been managed with antithyroid drugs and/or iodine as well as sedatives, propranol and digitalis when necessary. The purpose of this study was to evaluate the management of neonatal thyrotoxicosis using the radio-contrast agent iopanoic acid. METHODS: We managed five cases of neonatal thyrotoxicosis. All infants were treated initially with propranolol (1.7 mg/kg/day) and iopanoic acid 250 to 500 mg every third or fourth day. RESULTS: In all cases, clinical signs improved and T(3) and T(4) levels decreased dramatically within 24 to 72 hours. No toxic side effects were noted. CONCLUSION: Neonatal thyrotoxicosis can be managed successfully using iopanoic acid. Iopanoic acid is essentially free of side effects and need only be administered every 3 to 4 days. When administered until (transplacental) maternal TSI has been metabolized by the neonate, iopanoic acid maintains euthyroid status with no risk of hypothyroidism. With conventional therapy, propylthiouracil (PTU) must be administered three times a day. PTU also carries a significant risk of toxic side effects and a week or more of therapy is required to correct the hyperthyroid state and may induce hypothyroidism.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Recirculation of iopanoic acid after conjugation in the liver.

The purpose of the investigation was to determine if an enterohepatic recirculation occurred for the metabolite of iopanoic acid. The major metabolite of iopanoic acid (Telepaque) in dog bile is the glucuronide conjugate. The identification and quantitation of glucuronide conjugate was accomplished by elemental analysis, paper chromatography, thin layer chromatography, fluorescent excitation analysis, and high pressure liquid chromatography. The stability of iopanoic acid glucuronide in refrigerated dog bile was confirmed. Known amounts of the glucuronide conjugate were instilled into the duodenum of 8 awake adult dogs, and bile collected for 8 hours. Between 19% and 53% (average 31%) of the administered dose was recovered in bile, thereby documenting the presence of an enterohepatic recirculation of conjugated iopanoic acid. The slow rise and plateau of the excretion curve suggests that either the compound is absorbed slowly, or that absorption depends upon deconjugation in the gut. The implications are discussed.

Animals↗
PubMedDate not supplied

Pharmacokinetics of iopanoic acid in the rhesus monkey: biliary excretion, plasma protein binding and biotransformation.

A dynamic infusion method, originally developed for the pharmacokinetic studies of Iodoxamic acid, was applied to the kinetic studies of the biliary excretion of another cholecystographic agent, iopanoic acid. This dynamic method has an important advantage in that the pharmacokinetic parameters involved in the hepatic uptake or biliary excretion can be evaluated from a single infusion experiment. Using the equilibrium dialysis technique, iopanoic acid was found to be highly bound to the plasma proteins. A linear relationship was found when the logarithm of unbound plasma concentration of iopanoic acid was plotted vs. the logarithm of its blood concentration. When the biliary excretion rates of iopanoic acid were fitted by a computer to the Michaelis-Menten equation against its unbound plasma concentration, the average Vm value was found to be 0.85 micron/kg/min and the average Km value was found to be 0.253 micron. Iopanoic acid was found to exist in monkey blood as unchanged species and in the bile mainly as the ester glucuronide.

Animals↗
PubMedDate not supplied

Iopanoic acid as an adjunct to carbimazole in the management of hyperthyroidism.

BACKGROUND: The thiourea drugs take a few weeks to control the symptoms of hyperthyroidism whilst iodine containing radiographic contrast agents (iopanoic acid and sodium ipodate) have a more rapid effect. There is no report on the use of iopanoic acid administered in conjunction with carbimazole, so we evaluated the efficacy of this combination in the early medical management of patients with hyperthyroidism. METHODS: Thirty hyperthyroid patients diagnosed by clinical and biochemical criteria were randomized into two treatment groups. Group A (n = 16) received iopanoic acid (500 mg orally twice a day for the first 3 weeks) and carbimazole (30 mg orally in three divided doses) while group B (n = 14) received carbimazole alone. Clinical examination and estimation of serum total T3, total T4 and TSH were done by radioimmunoassay at the start of therapy, weekly for 4 weeks and then at 6, 8 and 12 weeks. RESULTS: In the initial 3 weeks, iopanoic acid induced a significantly greater fall in mean serum total T3 levels (Z = 2.298, p < 0.02) and a slower fall in mean serum total T4 (Z = 2.396, p < 0.05) in group A patients compared to those in group B. This was accompanied by earlier clinical improvement in group A patients. The mean serum total T3 and T4 values rose to higher levels in group A at 4 weeks, one week after discontinuation of iopanoic acid. At the end of 12 weeks, however, there was no significant difference in the mean serum total T3 and T4 levels between the two groups (p > 0.05). Biochemical euthyroidism (i.e. total T3 < 3 nmol/L and total T4 < 170 nmol/L) was achieved later in group A patients than in group B (10.4 +/- 5.0 weeks v. 3.6 +/- 1.2 weeks, p < 0.0001). CONCLUSIONS: Iopanoic acid given together with carbimazole induces rapid clinical improvement in hyperthyroid patients than carbimazole alone. However, the delayed achievement of euthyroidism may preclude its routine use in the management of patients with hyperthyroidism except in those with thyrotoxic emergencies.

Adult↗