Disclosures: Michael D. Smith, DO: No financial relationships or conflicts of interest
Case Description: Our patient, a 68 year-old-female has a long standing history of depression which has been managed with fluoxetine 80mg daily. She recently underwent and tolerated an intrathecal pump placement with ziconotide infusion for her chronic low back pain. A standard and guideline driven protocol for initial infusion rate and titration schedule was prescribed to reach a therapeutic dose. On the 7th day of her titration schedule, she presented with confusion, generalized weakness, and most notably, nystagmus on exam.
Setting: A community adult hospital.
Patient: A 68 year-old-female with 8-year history of chronic low back pain. Assessment/
Results: The infusion scheduled included an initial ziconotide rate of 2.4mcg/day, with an increase of 1.2mcg/day over a two week period with a max dose of 19.2mcg/day. On the 7th day of her titration schedule she presented to our emergency room and admitted for further work-up. The pump was interrogated which showed no malfunction and the infusion rate was decreased to the minimum with subsequent spontaneously resolved her symptoms.
Discussion: Ziconotide, a non-opioid calcium channel blocker, is a synthetic form of a marine snail conotoxin. It is indicated and approved for the treatment of chronic severe back pain. The drug is characterized by a narrow therapeutic window and must be carefully titrated. Concomitant drugs such as antidepressants and anticonvulsants may accelerate the risk for side effects observed with ziconotide as seen with our patient who was taking fluoxetine for depression.
Conclusion: This case outlines the need for more conservative and slower ziconotide titration schedules than guidelines recommend in individuals taking antidepressants, such as fluoxetine.
Level of Evidence: Level V
To cite this abstract in AMA style:
Smith MD. Accelerated Ziconotide Toxicity with Concomitant SSRI Use in a Chronic Back Pain Patient: A Case Report [abstract]. PM R. 2020; 12(S1)(suppl 1). https://pmrjabstracts.org/abstract/accelerated-ziconotide-toxicity-with-concomitant-ssri-use-in-a-chronic-back-pain-patient-a-case-report/. Accessed May 31, 2025.« Back to AAPM&R Annual Assembly 2020
PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/accelerated-ziconotide-toxicity-with-concomitant-ssri-use-in-a-chronic-back-pain-patient-a-case-report/