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[The adverse effects of thioureylene antithyroid drugs (author's transl)]
Abstract:
The aims of the present study were to investigate the incidence of adverse effects of thioureylene antithyroid drugs and to see if there were any factors related to the development of the adverse effects. Methimazole or propylthiouracil was administered to 151 patients with Graves disease; 76 untreated cases and 75 treated cases. The overall incidence was 22.4% among the 76 untreated cases. The incidences were 26.7% (13/45 cases) for methimazole and 16.1% (5/31 cases) for propylthiouracil, respectively, which were significantly higher than those previously reported. Fourteen out of 17 cases with the adverse effects were given the other thioureylene. The successive incidence of the adverse effects was 28.6% (4 cases), which was not significantly different from that under the drug of first choice. The result suggests that methimazole and propylthiouracil may not have cross-reaction each other. On the other hand, antinuclear antibody and anti-DNA antibody became positive in 2 out of the 4 cases. It would be a significant phenomenon, since antinuclear antibody was positive in only 3% of cases before the drug treatment. Thus, an immunological mechanism seemed to be involved in the problems, although there was no correlation between antithyroid autoantibodies and the development of the adverse effects. The adverse effects were observed within 2 months of administration of less than 250 tablets in total in most of the cases. The results imply that allergic mechanism rather than accumulating or toxic effect may concern the development of adverse effects of the thioureylenes.
Insights
Adverse effects from antithyroid drugs like methimazole and propylthiouracil occurred more frequently than previously reported. An allergic mechanism, not drug accumulation, is likely responsible for these side effects.
Area of Science:
- Endocrinology
- Pharmacology
- Immunology
Context:
- Graves disease treatment involves thioureylene antithyroid drugs.
- Adverse effects of these drugs can impact patient outcomes.
- Understanding the incidence and mechanisms of adverse effects is crucial for safe treatment.
Purpose:
- To investigate the incidence of adverse effects associated with methimazole and propylthiouracil.
- To identify factors contributing to the development of these adverse effects.
- To explore potential immunological mechanisms underlying drug-induced adverse events.
Summary:
- The study found higher incidences of adverse effects for methimazole (26.7%) and propylthiouracil (16.1%) than previously reported.
- Cross-reactivity between methimazole and propylthiouracil appears unlikely, as switching drugs did not significantly increase adverse event rates.
- An immunological mechanism, indicated by the emergence of antinuclear and anti-DNA antibodies, is suggested, though not correlated with existing autoantibodies.
- Adverse effects typically manifested early in treatment, within two months and with less than 250 tablets, suggesting an allergic rather than cumulative or toxic etiology.
Impact:
- Findings suggest an allergic mechanism for thioureylene antithyroid drug adverse effects.
- The low cross-reactivity indicates distinct safety profiles for methimazole and propylthiouracil.
- Early onset of adverse effects highlights the need for vigilant monitoring during initial treatment phases.
- The potential role of immunological factors warrants further investigation in managing antithyroid drug therapy.