Antineutrophilic Cytoplasmic Antibody Positive Vasculitis Associated with Methimazole Use

Comparison of agranulocytosis and anti-neutrophil cytoplasmic antibody-associated vasculitis caused by two antithyroid drugs: A pharmacovigilance study using the WHO international database

BACKGROUND

Methimazole (MMI) and propylthiouracil (PTU) are commonly used for patients with thyrotoxicosis. Agranulocytosis and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is associated with high morbidity and mortality, requiring appropriate interventions. In this study, we compared adverse drug effects associated with MMI and PTU using a real-world large pharmacovigilance database.

METHODS

We searched all Individual Case Safety Reports reported to be associated with MMI and PTU, from VigiBase between 1967 and June 2, 2021. We conducted disproportionality analysis (case/non-case analysis) to analyze the difference in reported adverse drug reactions (ADRs) between antithyroid drugs (case) and the entire database (non-cases). We further analyzed information for the cases of agranulocytosis and AAV.

RESULTS

Among 11 632 cases of ADRs reported after MMI intake, agranulocytosis occurred in 1633 cases and AAV occurred in 41 cases. For 5055 cases of ADRs reported after PTU intake, agranulocytosis occurred in 459 cases and AAV occurred in 110 cases. Agranulocytosis occurred after a median of 28 days after PTU intake and 33 days after MMI intake. More than 95% of the agranulocytosis cases were classified as serious, but most of them (65.1% for PTU and 70.4% for MMI) were reported to have recovered after dechallenge actions; mostly drug withdrawal. AAV occurred after a median of 668 days after PTU intake, and 1162 days after MMI intake.

CONCLUSIONS

This is a pharmacoepidemiological study investigating agranulocytosis and AAV caused by MMI and PTU. Through this research, we could provide more specific insights into a safe prescription of antithyroid drugs in a real-world setting.

Propylthiouracil-Induced Anti-Neutrophil Cytoplasmic Antibody Vasculitis Presenting with Red Eye Followed by Pulmonary Hemorrhage: Diagnostic and Management Considerations

Patient: Female, 34-year-old

Final Diagnosis: Vascuitis

Symptoms: Hemoptysis

Medication:—

Clinical Procedure: —

Specialty: Rheumatology

Methimazole-Induced Leukocytoclastic Vasculitis: A Case Report

Major identifiable causes of leukocytoclastic vasculitis include certain infections and medications. Amongst antithyroid drugs, methimazole (MMI) is rarely implicated as a culprit drug. We report the first case, in Thailand, of MMI-induced leukocytoclastic vasculitis in a 41-year-old Thai female who had received MMI for relapsed Graves' disease. MMI was discontinued and cholestyramine at a dose of 4 g four times daily was given instead. Her rashes on both legs resolved dramatically at 1-week follow-up. However, thyroid function test revealed unimproved thyrotoxicosis. She subsequently underwent radioiodine ablation as a definitive treatment. There were neither recurrent skin lesions nor other systemic involvements during the 3-month follow-up period. Notably, the most crucial step in the management of drug-induced leukocytoclastic vasculitis is the discontinuation of the offending drug in order to avoid further progression of the disease. The administration of immunosuppressive agents may not be necessary in patients with mild severity and non-vital organ involvement.