Here, we reported two cases with hyperthyroidism who complained of myalgia and muscle cramps during treatment with methimazole tablets (or Thyrozol, the brand name). One case experienced muscle cramps after taking Thyrozol for 6 months, and by this time the patient's thyroid function had returned to normal. In the other case, pain caused by muscular cramps began after the patient took Thyrozol for two weeks and the patient's thyroid function had not returned to normal yet at the time. In both cases, pain caused by muscle cramps appeared while the patients were taking Thyrozol. The myalgia persisted in spite of a reduction in the Thyrozol dose, but was significantly relieved with the discontinuation of Thyrozol. Myalgia and muscle cramps did not recur after the patients were switched to methimazole ointment. There was a strong temporal association between oral administration of Thyrozol and pain caused by muscle cramps, which may indicate that myalgia and muscle cramps are adverse reactions of Thyrozol. Looking into the relevant literature on the topic, we explored in this report the possible mechanisms of the onset of muscle cramps associated with Thyrozol, and compared the adverse reactions of two different formulations of methimazole, intending to provide more clinical experience for the treatment of hyperthyroidism and the management of rare adverse reactions related to antithyroid drugs.
本文报道了2例甲状腺功能亢进症患者在口服甲巯咪唑片（商品名：赛治）治疗期间出现痛性肌痉挛症状的病例。1例患者在服用赛治6个月后，甲状腺功能恢复正常，而出现了肌痛及肌肉痉挛症状；1例患者服用赛治半个月后，甲状腺功能尚未恢复正常，即开始出现了肌肉痉挛性疼痛。2例患者均于服用赛治期间出现痛性肌痉挛，将赛治减量后肌痛症状无缓解，停用赛治后症状明显好转，且改用甲巯咪唑软膏治疗后痛性肌痉挛症状也未再发生。2例患者出现痛性肌痉挛症状与口服甲巯咪唑呈明显的时间相关性，推断为口服赛治的不良反应。在本文中，我们结合以往的相关文献探讨了此不良反应发生的机制，同时也比较了2种不同剂型的甲巯咪唑发生不良反应的异同，从而为甲状腺功能亢进症的治疗以及抗甲状腺药物相关罕见不良反应的管理提供更多的临床经验。
Keywords: Adverse reactions; Methimazole ointment; Muscle cramps; Myalgia; Thyrozol.
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