Iodine adverse effects

Discuss the pharmacotherapy of Graves disease, including the advantages and disadvantages of antithyroid drugs versus radioactive iodine, adverse effects, and patient monitoring. 

This hot antibody is linked to radioactive iodine and binds to the CD20 receptor present on B lymphocytes (see Rituximab above). Tositumomab has shown activity in non-Hodgkin s lymphoma. Hematologic toxicity occurs several weeks after administration and may persist for months. Since radioactive iodine may have adverse effects on the thyroid, all patients must receive thyroid-blocking agents. 

Studies of low-dose perchlorate exposure in healthy human subjects A small number of studies have been published investigating the effects of low doses of perchlorate in thyroid function in healthy adults (without thyroid disease). One study was conducted in healthy male volunteers, involving the administration of 10 mg of perchlorate in drinking water for 14 days. A significant decrease in the uptake of iodine by the thyroid was observed at this dose, but there was no evidence of adverse effects on thyroid hormones or TSH concentrations [262]. Another recent study was conducted in healthy adults to determine the highest dose of perchlorate at which there is no effect on the uptake of iodine by the thyroid gland [263]. 

Clinical applications include preoperative suppression of thyroid secretion according to Plummer with Lugol s solution (5% iodine + 10% potassium iodide, 50-100 mg iodine/d for a maximum of 10 d). In thyrotoxic crisis, LugoTs solution is given together with thioamides and p-blockers. Adverse effects allergies contraindications iodine-induced thyrotoxicosis. 

Iodides should not be used alone since the normal gland will escape from iodide blockade in 2-8 weeks. Chronic use in pregnancy is not recommended because it crosses placenta and cause fetal goitre. Iodide treatment results in high intrathyroidal iodide content that can delay the onset of thioamide therapy or delay the use for radioactive iodine therapy for weeks if not months. Adverse effects include Hodism which is rare and reversible. The clinical symptoms are acneiform rash, sialadenitis, mucous membrane ulceration, conjuctivitis, rhinor-rhoea, metallic taste and rarely anaphylactoid reaction. 

Adverse effects include nausea, diarrhoea, abdominal discomfort, headache and goitre (so contraindicated in patients with intolerance to iodine). Prolonged use of iodochlorohydroxyquin causes subacute myelooptic neuropathy (SMON). They are indicated in giardiasis, trichomonas vaginitis, intestinal amoebiasis and amoebic colitis. 

In the USA, amiodarone is approved for oral and intravenous use to treat serious ventricular arrhythmias. However, the drug is also highly effective for the treatment of supraventricular arrhythmias such as atrial fibrillation. As a result of its broad spectrum of antiarrhythmic action, it is very extensively used for a wide variety of arrhythmias. Amiodarone has unusual pharmacokinetics and important extracardiac adverse effects. Dronedarone, an analog that lacks iodine atoms, is under investigation. 

Accidents with nuclear reactors or nuclear bombs can expose large numbers of people to several decay products of uranium, and iodine isotopes are among the most abundant compounds released in such reactions. It is therefore logical to use salts of stable isotopes of iodine to prevent the accumulation of radioiodine in a person or population at risk of such exposure. The accidents in Windscale (UK), Three Mile Island (USA), and particularly Chernobyl (Ukraine) drew attention to such problems. The major question is therefore whether the potential adverse effects of stable iodine when given indiscriminately to large... 

The main adverse effects of stable iodine are shown in Table 1. 

Iodine should be given to the general population if the risk of radioiodine exposure is sufficient (over 15-100 rem), but people with increased susceptibility to the adverse effects of iodine (previous thyroid disease or known serious allergies) should be excluded (11-16). In elderly people the benefit of stable iodine probably does not outweigh its potential adverse effects, while in pregnant women and infants the benefit to harm balance is not established rapid evacuation of such people from fallout zones should be given the highest priority (SEDA-11, 358). 

Because of its adverse effects, it is logical to omit iodine from all pharmaceutical formulations whenever possible, and at least clearly label its presence when it is necessary. The adverse effects of iodine include goiter and hypothyroidism (20,22), hyperthyroidism (SEDA-18,176), neutropenia (23), metabolic acidosis (24), and generalized iododerma (17). 

Table 1 Adverse effects of iodine given for protection against radioiodine...

It has been suggested that potassium perchlorate should be used in the treatment of type 1 hyperthyroidism and glucocorticoids in the treatment of type 2 (SEDA-21, 199). Since hypothyroidism due to amiodarone tends to occur in areas in which there is sufficient iodine in the diet, it has been hypothesized that an iodinated organic inhibitor of hormone synthesis is formed and that the formation of this inhibitor is inhibited by perchlorate to a greater extent than thyroid hormone iodination is inhibited, since the iodinated lipids that are thought to be inhibitors require about 10 times more iodide than the hormone. However, there is a high risk of recurrence after treatment with potassium perchlorate, and it can cause serious adverse effects (SED-13,1281). 

Adverse effects Amiodarone shows a variety of toxic effects. After long-term use, more than one half of the patients receiving the drug show side effects sufficiently severe to prompt its discontinuation. Some of the more common effects include interstitial pulmonary fibrosis, gastrointestinal tract intolerance, tremor, ataxia, dizziness, hyper- or hypothyroidism, liver toxicity, photosensitivity, neuropathy, muscle weakness, and blue skin discoloration caused by iodine accumulation in the skin. As noted earlier (see p. 166) recent clinical trials have shown that amiodarone did not reduce incidence of sudden death or prolong survival in patient with congestive heart failure (CHF). 

The safety of carbon dioxide in vena cavography has been investigated in 119 patients (aged 17-89 years, 65 men). Patients with intracardiac shunts, severe pulmonary compromise, or non-dialysis-dependent renal insufficiency were excluded. Two patients developed mild adverse effects one had nausea that resolved spontaneously and the other vomited several minutes after the administration of carbon dioxide but needed no treatment. The diagnostic quality of the venography was comparable to that with iodinated contrast media. The authors concluded that carbon dioxide cavography is well tolerated and is especially valuable in patients with a history of a reaction to iodinated contrast material or renal insufficiency. 

The radio-opacity of X-ray contrast media depends on the fact that they contain substances that have high atomic numbers, which absorb X-rays. Bismuth, now largely obsolete, has an atomic number of 83, barium 56. Since the soluble salts of barium are poisonous, the insoluble salt, barium sulfate, is used as a suspension. Soluble contrast media are based on iodine, which has an atomic number of 53. This means that in principle they can have the various adverse effects of other iodine-containing compounds. 

The main adverse effect of iodine-containing contrast agents after amniofetography is transient hypothyroidism, which has often been reported (236-246). 

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