COMPARISON OF STANDARDIZED INITIAL DOSES OF 2 ANTITHYROID DRUGS IN THE TREATMENT OF GRAVES-DISEASE

Objectives. To obtain a simple standard regimen, suitable for general practice, and based upon the addition of antithyroid drug plus thyroxi ne for attaining euthyroidism in patients with Graves' disease. Design . Prospective, randomized trial of patients with Graves' disease follo wed for 3 months after the initiation of therapy with an antithyroid d rug and combined with the later addition of triiodothyronine to keep t he patient euthyroid, The patients were randomized, according to birth date, between methimazole and propylthiouracil, Three dose schemes we re tested for each antithyroid drug. Setting. The study was performed at the thyroid outpatient units of two general hospitals, with the pat ients having been referred from primary care. Subjects. Ninety-four pa tients with Graves' disease who were suitable for treatment with antit hyroid drugs. Interventions. The patients were allocated into six grou ps. Three groups received methimazole (10 mg every 6th, 8th or 12th h) and three received propylthiouracil (100 mg every 6th, 8th or 12th h) . Twenty micrograms of triiodothyronine was added when the patients we re euthyroid to avoid hypothyroidism. Main outcome measures. The lowes t serum free thyroxine level within 3 months of the initiation of the antithyroid treatment. Results. Fourteen per cent of the patients on m ethimazole 10 mg every 12th h and 29% on propylthiouracil 100 mg every 12th h did not achieve euthyroidism within the 3-month observation pe riod, All but one patient on methimazole 10 mg every 8th h or propylth iouracil 100 mg every 8th h reduced the free serum thyroxine levels to the normal or hypothyroid range within the observation period. All of the patients on methimazole 10 mg every 6th h and 56% on propylthiour acil 100 mg every 6th h reduced the serum T4 values into the hypothyro id range within the period. Conclusion. A standard regimen, based upon the addition of methimazole 10 mg every 8th or 6th h or propylthioura cil 100 mg every 8th or 6th h and followed by the addition of thyroxin e or triiodothyronine when euthyroid to avoid hypothyroidism, seems to be suitable for attaining euthyroidism within 3 months in patients wi th Graves' disease, A dose scheme based on methimazole 10 mg every 12t h h or propylthiouracil 100 mg every 12th h were found to be unsuitabl e due to an unacceptably high incidence of failure to attain euthyroid ism or hypothyroidism within 3 months.