Thyroid drug preparations

Interferons are contraindicated in individuals with autoimmune hepatitis or other autoimmune disease, uncontrolled thyroid disease, severe cardiac disease, severe renal or hepatic impairment, seizure disorders, and CNS dysfunction. Immunosuppressed transplant recipients should not receive interferons. Interferons should be used with caution in persons who have myelosuppression or who are taking myelosuppressive drugs. Preparations containing benzyl alcohol are associated with neurotoxicity, organ failure, and death in neonates and infants and therefore are contraindicated in this population. Interferons should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. 

Bartalena L, Bogazzi F, Martino E. Adverse effects of thyroid hormone preparations and antithyroid drugs. Drug Saf 1996 15(l) 53-63. 

Thyroid hormone preparations used clinically are listed in Table 31-3. The primary problems associated with these agents occur with overdosage. Symptoms of excess drug levels are similar to the symptoms of hyperthyroidism (see Table 31-2). Presence of these symptoms is resolved by decreasing the dosage or changing the medication. 

Pharmaceuticals, chiral) Prostaglandins Psycopharmacologicalagents Steroids Thyroid and antithyroid preparations Veterinary drugs and Vitamins. 

When administered with cholestyramine or colestipol there is a decreased absorption of the oral thyroid preparations. These drugs should not be administered within 4 of 6 hours of the thyroid hormones. When administered with the oral anticoagulants there is an increased risk of bleeding. It may be advantageous to decrease the dosage of the anticoagulant when a thyroid preparation is prescribed. There is a decreased effectiveness of the digitalis preparation if taken with a thyroid preparation. 

The preferred thyroid preparation for maintenance replacement therapy is which of the following drugs ... 

Blockers are usually used as adjunctive therapy with antithyroid drugs, RAI, or iodides when treating Graves disease or toxic nodules in preparation for surgery or in thyroid storm. /3-Blockers are primary therapy only for thyroiditis and iodine-induced hyperthyroidism. 

Levothyroxine (L-thyroxine, T4) is the drug of choice for thyroid hormone replacement and suppressive therapy because it is chemically stable, relatively inexpensive, free of antigenicity, and has uniform potency however, any of the commercially available thyroid preparations can be used. Once a particular product is selected, therapeutic interchange is discouraged. 

The main role of the human thyroid gland is production of thyroid hormones (iodinated amino acids), essential for adequate growth, development, and energy metabolism (1-6). Thyroid underfunction is an occurrence that can be treated successfully with thyroid preparations. In addition, the thyroid secretes calcitonin (also known as thyrocalcitonin), a polypeptide that lowers excessively high calcium blood levels. Thyroid hyperfunction, another important clinical entity, can be corrected by treatment with a variety of substances known as antithyroid drugs. 

The silylation procedure has been accepted as a routine method for the trace analysis of preparations of thyroid hormones and drugs containing them. Quantitative evaluation was achieved by using T2 as an internal standard [314], The method has not been applied to the analysis of hormones in serum. Silylation does not seem suitable for this purpose as the derivatives partially decompose if sub-nanogram amounts are injected. 

Alcohol and some drugs can also affect calcium levels in the body, thus producing osteoporosis. Some of these drugs include thyroid medications, steroid preparations, anti-seizure medications, and certain chemotherapy (anti-cancer) agents. 

Quick relief can be obtained with a p-adrenoceptor blocking drug (judge dose by heart rate) though these do not block all the metabolic effects of the hormone, e.g. on the myocardium, and the basal metabolic rate is unchanged. For this reason they should not be used as sole therapy except in mild thyrotoxicosis in preparation for radioiodine treatment, and should be continued in these patients until the radioiodine has taken effect. They do not alter the course of the disease, nor biochemical tests of thyroid function. Any effect on thyroid hormonal action on peripheral tissues is clinically unimportant. It is desirable to choose a drug that is nonselective for pj and p2 receptors and lacks partial agonist effect (e.g. propranolol 20-80 mg 6-8-hourly, or timolol 5 mg once daily). Usual contraindications to P-blockade (see p. 478) should be observed, especially asthma. 

Hyperthyroidism (excessive production of thyroid hormones) asually requires surgery, but before. surgery the patient mu.st be prepared by preliminary abolition of the hyper-thyroidi.sm through the use of antithyroid drugs. Thiourea and related eompounds. show an antithyroid activity, but they arc too toxic for clinical use. The more useful drugs are 2-thiouracil derivatives and a closely related 2-thioimidazolc derivative. All of these appear to have a similar mechanism of action (i.c.. prevention of the iodination of the precursors of thyroxine and triiodothyronine). The main difference in the compounds lies in their relative toxieities. 

J. P. Stroraasli, E. L. Schoeniger, H. K. Hellerstein, H. L. Friedell, Thyroid ablation with I131 in euthyroid cardiac patients with special reference to preparation with antithyroid drugs, Radiology 4, El0-21 (1960). 

Administration of testosterone (C14, J4), thyroid hormones (M19), and ACTH (E5) has been shown to result in elevation of serum copper levels. The latter effect could have been due to contamination of the ACTH preparation with melanotropin (A2). Antithyroid drugs produce a fall in serum copper levels (F7). 

Any of the commercially available thyroid preparations accomplish this goal (Table 73-8) however, levothyroxine (1-thyroxine) is considered to be drug of choice. The thyroid preparations are either natural (i.e., desiccated thyroid and thyroglobulin) or synthetic (levothyroxine, fiothyronine, and fiotrix) in origin. The availability of sensitive and specific assays for total and free hormone levels as well as TSH... 

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