Q: 42 year old female with no significant past medical history except for hypertension, presented to ER with dizziness and  palpitations. Initial rhythm showed runs of V.Tach. Only significant description given in history is recent episode of UTI (urinary tract infection) for which she was prescribed antibiotics by an urgent care physician. Which drug interaction is suspected?

Answer: Bactrim (Trimethoprim-sulfamethoxazole) and ACE-Inhibitor (ACE-I)

Among patients treated with ACEIs or ARBs, the use of Bactrim is associated with a life threatening hyperkalemia, in comparison to other antibiotics. Alternate antibiotic therapy should be considered in such situation.