芍薬甘草湯により意識消失発作を来した1例

Unconsciousness induced by “Shakuyaku-Kanzou-tou”: a case report

要旨　患者は77歳の女性で，意識消失により救急搬入された．7ヵ月前より整形外科で芍薬甘草湯が投与されていた．血圧58/30mmHg，脈拍80/分・不整，意識レベルはIII-300（JCS）であった．血液検査で筋原性酵素値の上昇や著明な低カリウム血症が認められた．心電図では心室性期外収縮の2段脈および著明なQT延長，胸部X線写真では心不全所見が認められた．キシロカインの静注により意識レベルはIII-100からII-20と改善した．低カリウム血症および荷薬甘草湯の服用歴から偽性アルドステロン症と診断した．芍薬甘草湯を中止し，カリウムを補正した．意識レベルは第2病日に改善し，四肢の脱力とCPKの上昇は第4病日，心不全は第6病日，低カリウム血症は第7病日に正常化した．意識消失の原因として低カリウム血症による不整脈が考えられた．偽性アルドステロン症では甘草成分のグリチルリチンが原因で低カリウム血症が出現する．漢方製剤でも重篤な副作用の合併があり，慎重な投与が必要である．

　A 77-year-old woman was emergently admitted to our hospital in an unconscious condition. She had been receiving “Syakuyaku-kanzoutou”, a Chinese medicine that contains glycyrrhizin, at an orthopedic hospital for one month prior to admission. On examination blood pressure was 58/30mmHg, pulse rate was 80/min irregular and her consciousness level was III-300 (Japan Coma Scale). On laboratory data, the levels of myogenic enzymes were markedly elevated, and the levels of serum potassium and aldosterone were markedly depressed. Electrocardiography showed bigeminy of premature ventricular contraction and marked prolongation of QT interval. Chest radiography showed severe congestive heart failure. We made a diagnosis of pseudoaldosteronism because of the elevation of myogenic enzyme, hypokalemia and prescription of “Syakuyaku-kanzoutou”. We stopped all prescriptionsand corrected the level of serum potassium, and her consciousness level was improved on the second hospital day. Muscle weakness in extremities, CPK elevation, congestive heart failure and hypokalemia were improved on the 2nd, 4th, 6th and 7th hospital days, respectively. Coronary angiography on the 21st hospital day showed no significant stenosis. We considered that the loss of consciousness in this case was caused by arrythmia, heart failure and hypokalemia. In pseudoaldosteronism, hypokalemia is induced by pseudoexcess of mineralcorticoid, which was caused by glycyrrhizin, one of the principal ingredients of “Kanzou”. In prescribing Chinese medicine rare but serious side effects should be taken into consideration.