A 69-year-old man was transferred to our hospital because of severe general
fatigue and progressive systemic
muscle weakness. He had taken 300 mg/day of
cibenzoline for his sustained
ventricular tachycardia (VT) for years. At the end of June 2001 he began to feel general
fatigue, which slowly progressed to systemic
muscle weakness and walking disturbance. On 2nd July 2001, he finally could not stand up by himself. He also felt
dyspnea. He was transferred to our emergency room, where he developed severe
respiratory depression. Acute
myocardial infarction was ruled out based on his ECG and blood chemistry data. Serum BUN and
creatinine were elevated to 32 and 2.2 mg/dl, respectively, which returned to normal range 2 weeks later. What we did in our ICU were basically a replacement of
cibenzoline with
mexiletine and mechanical support of ventilation. As his renal function gradually improved, his spontaneous respiration and muscle power were slowly restored. He was discharged on foot after 1 month of hospitalization. His blood
cibenzoline content taken 2 days after the cessation of
cibenzoline was 959.6 mg/ml that was abnormally elevated. Considering metabolism and excretion for the 2 days between the
cibenzoline cessation and the blood sample drawing, his
cibenzoline level on the day of admission must have been extraordinary high. We should be aware of the possibility of abrupt overdosage of
cibenzoline even in patients with normal kidney function in the event of a transient or an acute renal dysfunction.