An acute phase reaction from zoledronate mimicking symptoms seen in opioid withdrawal: a case report

Zoledronate, a bisphosphonate, is a potent first-line treatment for osteoporosis. It is also a preferred treatment for hypercalcemia especially when unresponsive to intravenous fluids. Bisphosphonates can cause acute phase reactions that mimic opioid withdrawal symptoms, which can confound provider decision-making. Our case highlights cognitive bias involving a patient with opioid use disorder who received zoledronate for hypercalcemia secondary to immobilization and significant bone infection.

A 41-year-old male is admitted with a past medical history of active intravenous opioid use complicated by group A streptococcal bacteremia with L5-S1 discitis and osteomyelitis, L2-L3 osteomyelitis, and left ankle abscess/septic arthritis status post left ankle washout. His pain was well-controlled by acute pain service with ketamine infusion (discontinued earlier), opioids, acetaminophen, buprenorphine-naloxone, cyclobenzaprine, gabapentin, and naproxen. Intravenous opioids were discontinued, slightly decreasing the opioid regimen. A day later, the patient reported tachycardia, diaphoresis, myalgias, and chills, which the primary team reconsulted acute pain service for opioid withdrawal. However, the patient received a zoledronate infusion for hypercalcemia, on the same day intravenous opioids were discontinued. He had no other medications known to cause withdrawal-like symptoms per chart review. Therefore, it was suspected that an acute phase reaction occurred, commonly seen within a few days of bisphosphonate use.

Zoledronate, well known for causing acute phase reactions, was likely the cause of withdrawal-like symptoms. Acute phase reactions with bisphosphonates mostly occur in the first infusion, and the incidence decreases with subsequent infusions. Symptoms typically occur 24-72 h post-infusion, and last at most for 72 h. Cognitive bias led the primary team to be concerned with opioid withdrawal rather than investigating other causes for the patient's presentation. Therefore, providers should thoroughly investigate potential etiologies and rule them out accordingly to provide the best care. Health care providers should also be aware of the implicit biases that potentially impact the quality of care they provide to patients.