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PubMed1988

Effect of simultaneously administered iopanoic acid and thyrotropin releasing hormone (TRH) on thyroid hormone metabolism in euthyroid subjects.

The cause of serum T4 elevation after iopanoic acid administration was searched in euthyroid subjects. 3 gr iopanoic acid was given per os to 9 healthy volunteers (group I), in other 5 volunteers a TRH test was performed prior to iopanoic acid administration (group II). In group I TSH, T4, FT4I and rT3 levels increased, in group II T3 and FT3I decreased, but no TSH, T4, FT4I increase was seen, obviously, because of the exhaustion of pituitary TSH content by TRH. On the ground of the findings T4 elevation caused by iopanoic acid is predominantly consequence of TSH release and not that of inhibited T4 conversion rate.

Adult↗

PubMed1990

Calorie restriction and iopanoic acid effects on thyroid hormone metabolism.

We measured the effects of iopanoic acid on thyroid hormone metabolism in obese men during severe calorie restriction to study the nutrition regulation of thyroid hormone metabolism. Eight morbidly obese men received a weight-maintenance diet followed by 6 wk of 600 kcal/d. During underfeeding, patients received iopanoic acid or placebo for 2-wk periods in a double-blind crossover fashion. Underfeeding alone (UF) produced a 28.3% decline in the serum triiodothyronine (T3) concentration, and iopanoic acid plus underfeeding (IOP) produced a 49.5% decline in T3 concentration from baseline. Serum reverse T3 concentrations increased 289% during IOP compared with UF alone (p less than 0.001). Serum TSH concentration was unchanged by underfeeding but increased twofold during IOP treatment. Thyroid hormone kinetics demonstrated a decrease in T3 production during IOP compared with UF. These findings suggest that calorie restriction regulates T3 production by modulating only type I 5'-deiodinase activity.

Adult↗

PubMed1992

The plasma pharmacokinetics of iophenoxic and iopanoic acids in goat.

1. The comparative plasma pharmacokinetics of two organic iodine-containing compounds were evaluated in the goat for their suitability as markers in wildlife studies. 2. After oral administration of a single dose, the plasma elimination half-life for iopanoic acid was considerably more rapid (t1/2 of 1-2 days) than that of iophenoxic acid (t1/2 of 81 days). 3. Similar peak plasma concentrations were obtained after administration of iophenoxic acid (1.5 mg/kg) and iopanoic acid (25 mg/kg); however, the AUC0----infinity for iopanoic acid at doses of 25, 50, and 100 mg/kg were 201 +/- 39, 604 +/- 225, and 1292 +/- 721 (micrograms h/ml +/- SD), respectively, which were less than the value of 36,600 +/- 6387 for the oral administration of iophenoxic acid at 1.5 mg/kg. 4. Iophenoxic acid was chosen as a suitable marker because of its persistence at detectable concentrations in the plasma for 5 months.

Animals↗

PubMed1979

Physical characterization of solid iopanoic acid forms.

Three solid forms of iopanoic acid were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, thermal microscopy, IR spectroscopy, and dissolution studies. X-ray analysis demonstrated that two solid forms were crystalline and that the third was amorphous. The amorphous form had been reported previously as crystalline. Enthalpies and entropies of transition were calculated using differential scanning calorimetry. A fourth form, a benzene solvate, also was isolated but proved to be too unstable at room temperature to permit conclusive characterization. The amorphous form demonstrated a 10-fold greater intrinsic dissolution rate than the commercially available form (Form I). Form II's intrinsic dissolution rate was 1.5 times greater than that of Form I. In powder dissolution studies, the peak solubilities of the different forms followed the same rank order as their intrinsic dissolution rates. Form II was relatively stable in aqueous saturated solutions, but the amorphous form was rapidly converted to Form I under similar conditions.

Calorimetry, Differential Scanning↗

PubMed2004

Treatment of hyperthyroidism associated with thyrotropin-secreting pituitary adenomas with iopanoic acid.

TSH-secreting tumors comprise less than 2% of all pituitary adenomas. All patients present with hyperthyroidism with a detectable TSH level, and a majority have macroadenomas. Oral cholecystographic agents (e.g. iopanoic acid) potently inhibit the activation of T(4) to the more potent T(3). They have been used successfully to treat primary thyroidal hyperthyroidism and thyroxine overdose. However, they have not been employed in the treatment of central hyperthyroidism. We report, herein, the first two patients with thyrotropinomas, in whom iopanoic acid (Telepaque) has been used perioperatively to safely and rapidly achieve euthyroidism. In case 1, free T(3) index improved from a value of 634 to 175 (normal range 78-162) after 3 d of therapy with iopanoic acid. In case 2, free T(3) by dialysis improved from 697 pg/dl (10.7 pmol/liter) to 195 pg/dl (3.0 pmol/liter) (normal range 210-440 pg/dl; 3.2-6.7 pmol/liter) after 7 d of therapy with iopanoic acid.

Adenoma↗

PubMed1981

Acute thrombocytopenia following oral cholecystography with iopanoic acid.

We report a case of severe thrombocytopenia following oral cholecystography with iopanoic acid, a widely used contrast medium. A bone marrow aspirate showed increased numbers of megakaryocytes, suggesting a thrombocytopenia due to enhanced peripheral destruction of platelets; this examination was not reported in the previously described two cases. Although hematological reactions due to iopanoic acid are very rare, it would be wise to question patients regarding any preceding drug-induced purpura before proceeding with oral cholecystography.

Administration, Oral↗

PubMed2001

A test of the hypothesis that T3 is the "seasonality" thyroid hormone in American tree sparrows (Spizella arborea): intracerebroventricular infusion of iopanoic acid, an inhibitor of T3 synthesis and degradation.

This study tested the hypothesis that L-3,5,3'-triiodothyronine (T3) is the bioactive "seasonality" thyroid hormone in American tree sparrows (Spizella (arborea). The experimental approach coupled thyroid hormone replacement therapy after radiothyroidectomy with photostimulation and intracerebroventricular infusion of iopanoic acid, an inhibitor of L-3,5,3'-triiodothyronine synthesis and degradation. Endpoints were testis length, molt score, and hypothalamic content of chicken gonadotropin-releasing hormone 1. The hypothesis predicts that thyroidectomized male tree sparrows moved to long days and given thyroxine in combination with iopanoic acid will lack L-3,5,3'-triiodothyronine and so will not express thyroid hormone-dependent photoperiodic testicular growth (a vernal component of seasonality) and photorefractoriness or postnuptial molt (autumnal components of seasonality). It further predicts that iopanoic acid will enhance the efficacy of L-3,5,3'-triiodothyronine and so will facilitate the expression of seasonality in thyroidectomized males given L-3,5,3'-triiodothyronine replacement therapy. Iopanoic acid had no significant effect on any component of seasonality in thyroid-intact males given vehicle, or in thyroidectomized males given thyroxine or L-3,5,3'-triiodothyronine. Thyroid-intact males, as well as thyroidectomized males infused with thyroxine alone, commonly expressed all components of seasonality. Thyroidectomized males given L-3,5,3'-triiodothyronine alone exhibited photoperiodic testicular growth, but did not become photorefractory or initiate molt. While these results confirm that thyroid hormone acts centrally to program American tree sparrows for seasonality, they do not support the hypothesis that L-3,5,3'-triiodothyronine is the bioactive "seasonality" thyroid hormone, and they challenge the view that thyroxine is merely a prohormone.

Animals↗

PubMed1976

The biliary and urinary excretion of iopanoic acid: pharmacokinetics, influence of bile salts, and choleretic effect. An experimental study in bile-fistula dogs.

The biliary and urinary excretion and the choleretic effect of iopanoic acid (Telepaque) were studied in nonanesthetized bile-fistula dogs using a stepwise increase of infusion rates of iopanoic acid and a constant infusion of sodium taurocholate at a rate of either 0.5 or 2.0 mumoles/min./kg. The maximum rate of bile excretion (0.671 mumoles/min./kg) when taurocholate was infused at the lower rate nearly doubled (1.325 mumoles/min./kg) when given at the higher rate. Maximum biliary concentrations of iopanoic acid at both rates of taurocholate infusion (70-77 mumoles/ml) were almost double the maximum concentration previously determined for iodipamide (Cholografin) (42 mumoles/ml).

Animals↗

PubMedDate not supplied

Gallbladder density and iodine concentration in humans during oral cholecystography. A comparison of iopanoic acid and iopronic acid.

A comparison of two oral cholecystopaques, iopanoic acid (Telepaque) and iopronic acid (Oravue), was performed using normal volunteers. Using a double-blind crossover design, comparisons were made between the degree of gallbladder opacification and the amount of iodine recovered from the gallbladder. Bile was collected via a double lumen intestinal tube before, during, and after stimulating gallbladder contraction. There were no differences between the two agents in terms of opacification or iodine concentration. Only 19% of the administered dose of either agent was recovered, and the maximum iodine concentration in bile was 10 mg I/ml. The results suggest that this technique has merit for future comparative studies of agents concentrated in the gallbladder.

Administration, Oral↗

PubMed1980

Fractionated dose cholecystography: a comparison between iopanoic acid and sodium ipodate.

Two randomised groups of 100 subjects each, undergoing oral cholecystography, were given either a 6 g fractionated dose of iopanoic acid (Telepaque) or sodium ipodate (Biloptin) to determine the relative merits of this dose schedule. Exclusions to the study were pregnancy and iodine sensitivity. Calculi or abnormal gallbladder opacification were present in 45% of subjects. Both agents were equally effective in demonstrating abnormalities, although bile duct visualisation was better using iopanoic acid (P less than 0.05). Of 46 subjects with abnormal cholecystograms subsequently undergoing surgery, all had the diagnosis confirmed. Side effects occurred in 63% of all subjects, being twice as common in those taking iopanoic acid (P less than 0.01). Sodium ipodate in a large fractionated dose is favoured because of the lower occurrence of side effects without loss of diagnostic accuracy.

Cholecystography↗

PubMedDate not supplied

Biliary and urinary excretion of iopanoic acid in the dog.

The urinary and biliary excretion of iopanonic acid was studied in anesthetized dogs infused with sodium iopanoate and trace amounts of 125I-iopanoic acid to provide a wide range of plasma concentrations. Samples of kidney and liver were also analyzed for total radioactivity. The sole excretory product in urine and bile was the glucuronide conjugate. The secretory biliary Tm for for iopanoic acid varied between experiments. Biliary concentration far exceeded that of plasma and liver/plasma ratios were all greater than unity. The fractional rate of urinary excretion varied 1-80% and was strongly correlated with hepatic function, e.g. the rate of bile flow. The data are interpreted to indicate that, depending on the rate of bile flow, the glucuronide formed in the liver is partioned between bile and blood, the latter for urinary excretion. This mechanism is discussed in relation to cholecystographic visualization and to the problem of nephrotoxicity.

Animals↗

PubMed1978

The effect of nonfractionated and fractionated administration of iopanoic acid on gallbladder visualization.

Visualization of the gallbladder after nonfractionated and fractionated administration of iopanoic acid was investigated in a blind experiment. The authors studied 168 patients; 73 were given 3 g iopanoic acid over a period of 6 hours (0.5 g/hour), and 95 received the same amount of contrast medium in a single dose. No differences in visualization were found for the two modes in both normal and pathological cases.

Cholecystography↗

PubMedDate not supplied

Physiologic pharmacokinetic model of iopanoic acid metabolism in rats.

The kinetics of iopanoate metabolism have been examined using a physiologic and pharmacokinetic model in rats. The kinetics of iopanoic acid concentration in blood and in eight other major tissue distribution compartments have been determined and fitted to computer-generated concentrations based on a well-established pharmacokinetic model. The results of these studies in nonfasted, conscious rats revealed that after gastric administration of the contrast material tissue concentrations never exceed 30 microgram/g even in the liver. In addition, a clear-cut enterohepatic circulation of the drug was noted in the experimental setting and had to be incorporated into a computer-generated model to account for differences in the predicted model as compared to the experimental data. Such data point out the importance of knowledge of pharmacokinetics of a drug for development of more appropriate dosage regimens of older compounds, theoretical design and testing of new compounds, or to explain clinically observed drug-related phenomenon.

Animals↗

PubMed1987

Iododerma occurring after orally administered iopanoic acid.

A 45-year-old man with multiple myeloma developed iododerma after oral cholecystography with iopanoic acid. The lesions appeared two days after two exposures to iopanoic acid given within one week. To our knowledge, this is the first reported case of iododerma in association with multiple myeloma and orally ingested radiocontrast dye.

Administration, Oral↗

PubMed1987

Long term treatment of Graves' disease with iopanoic acid (Telepaque).

To investigate the long term utility of the cholecystographic contrast agent iopanoic acid (Telepaque) for treatment of Graves' hyperthyroidism, we studied 40 patients treated with 500 mg, orally, daily for 1-12 months. We measured thyroid size; body weight; serum T3, T4, and free T4 concentrations; and antithyroglobulin and antimicrosomal antibody levels at monthly intervals. Based on the effects of the therapy, the patients were divided into 3 groups: 6 patients had excellent responses with return of serum thyroid hormone levels to normal (group A); 12 patients had fair responses, but 1 thyroid hormone test remained elevated (group B); and 22 patients had minimal benefit (group C) with only slight clinical improvement and transient reduction of serum T3 concentration. Mean serum T3 levels decreased significantly after 1 month of therapy in all 3 groups and became normal in groups A and B, but the reduction in group C was not sustained. Mean serum T4 and free T4 levels remained above normal during the course of therapy in groups B and C. Sixty-eight percent of patients in group C had large goiters compared with 33% of group A and 25% of group B, and those in group C tended to have more severe biochemical hyperthyroidism initially. There were no significant changes in antibody titers during therapy. These data indicate that iopanoic acid is not effective therapy for many hyperthyroid patients.

Adolescent↗

PubMed1998

Successful treatment of massive acute thyroid hormone poisoning with iopanoic acid.

We report a toddler with massive thyroid hormone poisoning in whom the addition of iopanoic acid to the treatment regimen (propylthiouracil and propranolol) resulted in a dramatic clinical and biochemical improvement. Iopanoic acid is a safe and effective drug in the treatment of massive thyroid hormone poisoning in children.

Child, Preschool↗

PubMed2006

Combination of minimally invasive thyroid surgery and local anesthesia associated to iopanoic acid for patients with amiodarone-induced thyrotoxicosis and severe cardiac disorders: a pilot study.

BACKGROUND AND AIMS: Amiodarone-induced thyrotoxicosis is a life-threatening condition. A prompt control of thyrotoxicosis is obtained by thyroidectomy. Preparation with iopanoic acid proved to be very effective in reducing cardiovascular complications. Nevertheless, general anesthesia and extensive surgery may affect negatively patients also after adequate preparation. Safety and efficacy of minimally invasive video-assisted thyroidectomy performed under regional anesthesia (bilateral modified deep cervical block) in patients with amiodarone-induced thyrotoxicosis was evaluated. PATIENTS AND METHODS: Eight patients with amiodarone-induced thyrotoxicosis (three with type I and five with type II), mean age 66.2 years, were prepared with iopanoic acid. There were five men and three women. Three patients had dilatative cardiomyopathy, three had heart failure secondary to severe myocardial infarction, and two had refractory unstable rhythm disorders. RESULTS: Minimally invasive video-assisted thyroidectomy was performed under regional anesthesia. Mean operative time was 55.5 min. During surgery, lung and heart function remained well and no surgical complications occurred. After surgery, all patients remained on amiodarone therapy and two patients were subsequently removed from the checklist for heart transplantation. CONCLUSION: Minimally invasive video-assisted thyroidectomy under regional anesthesia can be proposed as resolution of amiodarone-induced thyrotoxicosis in high risk patients with severe cardiac disorders, after preparation with iopanoic acid.

Aged↗

PubMed1985

Iopanoic acid is of minimal benefit in the treatment of severe hyperthyroidism: conclusions from a case study.

Iopanoic acid (1 g/d) was used together with propylthiouracil (1200 mg/d) in the treatment of a patient with very severe hyperthyroidism and associated cardiac failure. Although serum total T3 decreased by 75% within 48 h and reached normal after 72 h, free T3 levels did not fall to normal. Total and free T4 remained markedly elevated and features of hyperthyroidism persisted. Estimations of theoretical in vivo occupancy of nuclear thyroid hormone receptors, based on serum free T4 and free T3, suggest that the marked decrease in total T3 would not result in a corresponding decrease in thyroid hormone action. Hence, estimates of potential benefit from oral cholecystographic contrast agents, based only on measurements of total T3, may be unduly optimistic. When temporary agranulocytosis developed in this patient, the prior use of iopanoic acid, by markedly reducing thyroidal iodine uptake, restricted the therapeutic options. Caution should, therefore, be exercised in the use of iodine-containing contrast media as adjunctive antithyroid agents.

Cell Nucleus↗