Iodine anti-thyroid drugs

Interaction of Thioamides, Selenoamides and Amides with Di-iodine A Study of the Mechanism of Action of Anti-thyroid Drugs... 

Keywords Anti-thyroid drugs, amides, iodine interaction, selenoamides, thioamides... 

Interestingly, the value of formation constant Kc of a complex with iodine has been used as a measure for evaluation of anti-thyroid activity of such compounds. The complexes of morpholine with iodine were shown to be of the n-o type with a 1 1 stoichiometry. A strong donor-acceptor interaction was found in this complex (Kc = 1261 12 moP at 20 °C in CCLt). This is considerably higher than analogous characteristics of complexes of aromatic compounds with iodine. The high value of the formation constant for this complex indicates that morpholine could serve as a starting point for the synthesis of novel anti-thyroid drugs [16]. 

A high radioactive iodine neck uptake test (q.v.) is usually indicative of hyperthyroidism, although a high uptake can occur if the patient is iodine deficient or is taking anti-thyroid drugs. The neck uptake test can therefore be repeated after triiodothyronine (T3) administration. This normally suppresses TSH secretion, resulting in a low uptake. However, in hyperthyroidism but not in the other conditions listed above, no such suppression occurs. 

Figure 96.3 Structures of amiodarone, DEA and thyroid hormones. Amiodarone is a type 3 anti-arrhythmio drug that is an iodine-rich benzofuran derivative. It is metabolized through dealkylation to desethylamiodarone (DEA), whioh is the aotive metabolite. Amiodarone and DEA share a structural resemblance with thyroid hormones.

Amiodarone, an anti-arythmic drug containing 37.2 % of organic iodine, may induce hypothyroidism and hyperthyroidism. Dysthyroidism can occur during treatment, but also many months after its discontinuation in patients with underlying thyroid disorders, as well as in subjects with apparently normal glands. We report the case of a patient who developed hypothyroidism followed by hyperthyroidism, related to amiodarone therapy. 

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