Faculty Bibliography

BACKGROUND: Management of a hyperthyroid patient unable to take oral or rectal medication is a difficult clinical problem. The need for an alternative parenteral route of antithyroid medication administration in thyrotoxic patients occurs in certain rare cases, such as emergent gastrointestinal surgery, bowel ileus or obstruction, or severe vomiting and diarrhea. We report a simple and successful protocol for the preparation and use of intravenous methimazole (MMI) for treatment of hyperthyroidism in patients intolerant of orally and rectally administered thionamides. METHODS: Five hundred milligrams of methimazole USP powder was reconstituted with pH-neutral 0.9% sodium chloride solution to a final volume of 50 mL using aseptic technique, then filtered through a 0.22-microm filter. MMI injection was administered as a slow intravenous push over 2 minutes and followed by a saline flush. CASES: A 76-year-old man, intolerant of oral and rectal medications because of an ileus and intractable diarrhea, who developed worsening thyrotoxicosis after an emergent spinal cord decompression, and a 42-year-old man with chronic liver disease and hyperthyroidism, requiring emergent exploratory laparotomy and maintenance of complete bowel rest because of persistent gastrointestinal bleeding were rendered euthyroid using intravenous MMI. CONCLUSION: Two cases of hyperthyroidism successfully treated with a preparation of intravenous MMI are described.

BACKGROUND: The use of immunosuppressant agents is mandatory in the long-term management of transplant recipients. Herein, we report a case of near fatal cardiac arrhythmia related to the use of intravenous tacrolimus in a 35-year-old woman undergoing renal transplantation. METHODS: The patient had no previous history of cardiac disease, but an initial electrocardiogram demonstrated slightly prolonged QT and QTc intervals and normal sinus rhythm. Postsurgical immunosuppression included intravenous tacrolimus and methylprednisolone. During intravenous tacrolimus infusion, marked QT prolongation occurred. The patient suffered recurrent runs of torsade de pointes, refractory to aggressive medical management and requiring numerous defibrillations. Rapid atrial pacing eventually controlled the arrhythmia. RESULTS: We note not only a temporal association, but also a direct linear relationship, between this arrhythmia and blood tacrolimus levels. CONCLUSION: We believe this case presents a little recognized hazard associated with the use of intravenous tacrolimus and points to the need for careful predrug screening for QT prolongation. Tacrolimus has been shown to effect intracellular calcium and to prolong the action potential duration experimentally. This suggests that an increase in the intracellular calcium may underlie torsades de pointes associated with intravenous tacrolimus.