727 - A case of rhabdomyolysis: Induced by a statin or trimethoprim-sulfamethoxazole?

Case Diagnosis: Rhabdomyolysis, likely induced by trimethoprim-sulfamethoxazole.

Case Description: A 67-year-old Hispanic American male with a history of alcohol-related liver cirrhosis, dyslipidemia, type 2 diabetes mellitus presented for 3 days of progressive bilateral lower extremity weakness and pain. Symptoms began on his 7th day of taking trimethoprim-sulfamethoxazole, prescribed for spontaneous bacterial peritonitis prophylaxis on recent prior admission. Workup revealed myoglobinuria, elevated creatine kinase >20,000 IU/L, and transaminitis and he was aggressively resuscitated with fluids. Additional workup with HMG-CoA reductase IgG antibody test and serum myositis panel were negative and antibiotic-induced rhabdomyolysis is suspected after other infectious, inflammatory, autoimmune causes were ruled out. Given that his symptoms had progressed to an inability to stand independently, he worked with physical therapy during admission and was discharged to a skilled nursing facility prior to returning home.

Discussions: As is true with many antibiotics, TMP-SMX is associated with a multitude of potential side effects, some rare and potentially life-threatening. While the importance of antibiotics in medical practice is undeniable, in this instance there was no evidence-based indication for initiation of SBP prophylaxis in a patient with no history of prior SBP, ascites, or gastrointestinal hemorrhage, serving as an important reminder for prescribing providers to practice antibiotic stewardship and consider the necessity of each medication.

Conclusions: It is important to remember to keep a wide differential and that the typical offending medication may not be the culprit ultimately. While statins are classically taught to induce rhabdomyolysis, the actual occurrence is infrequent at a < 0.1% risk. Our patient’s clinical course was not consistent with the timeframe for statin-related injury and TMP-SMX was the only new medication initiated prior to symptom onset. Ultimately, in addition to confirmatory laboratory rule out of statin-induced myonecrosis, his home high dose statin was eventually resumed without recurrence of symptoms indicating TMP-SMX as the culprit.