類風濕關節炎病人長期服用低劑量Methotrexate於併服Trimethoprim- Sulfamethoxazole後發生泛血球低下症－－病例報告

Rheumatioid Arthritis Patient on Low Dose Methotrexate Develops Pancytopenia Complications After Receiving Trimethoprim-Sulfamethoxazole-- A Case Report

頑固性風濕性關節炎使用低劑量脈衝式methotrexate已被證實為有效且安全之療法；然而當病人若有血清中methotrexate濃度上升或有葉酸缺乏之危險因子出現時，則可能會併發罕見的泛血球低下症。吾人報告一例七十九歲女性病人由於頑固性關節炎，七個多月來，每週服用脈衝式低劑量methotrexate 10毫克，獲得症狀之改善。但是在一次拔牙後併服trimethoprim 160毫克－－sulfamethoxazole 800 毫克，每天2次，每次2錠，2天後，發生口腔潰瘍，胃潰瘍並解黑便，其後更發生嚴重的泛血球低下症與急性膽囊炎。住院後終止服用methotrexate和trimethoprim- sulfamethoxazole，同時輸血，投以抗生素與leucovorin治療後，病人於二十二天後順利出院。本文針對造成泛血球低下症因素加以討論，並且建議使用低劑量methotrexate的病人應定期追蹤血球數目，尤其在具有造成葉酸缺乏之危險因子或其症狀時更應如此。

Low dose pulse methotrexate (MTX) given weekly for refractory rheumatoid arthritis (RA) has been proved to be both effective and safe. Pancytopenia is a rare complication which usually occurs in patients with risk factors predisposed to elevated serum MTX level and folate deficiency. We report a 79-year-old female patient who received low dose pulse MTX therapy weekly for intractable RA for over 7 months with symptomatic improvememt. However, oral ulcers, gastric ulcer with tarry stool, and disproportionally severe pancytopenia developed after receiving two days of trimethoprim 160mg- sulfamethoxazole 800mg (TMP-SMX) for infection prophylaxis following a tooth extraction. After withdrawal of offending medications, blood transfusion, antibiotics, and leucovorin therapy, she was discharged in 3 weeks. We ascribed TMP-SMX as a predisposing factor to her pancytopenia. In patients with RA who are receiving MTX therapy, frequent monitoring of hemogram is necessary and avoidance of factors which may affect MTX level and/or folate deficiency should be instituted.