Psychiatric Predisposition to Autonomic and Abnormal Perception Side-Effects of Ziconotide: A Case Series Study

Abstract

Ziconotide is a reversible blocker of the N-type neuronal voltage-sensitive calcium channels with analgesic effects. The main adverse effects of ziconotide are ataxia, dizziness, gait disorder, confusion, hallucinations, and gastrointestinal symptoms. Eighteen chronic pain patients with intrathecal ziconotide treatment were investigated using the Mini International Neuropsychiatric Interview for psychiatric disorders according to the DSM IV. Ten patients showed good pain relief (ΔVAS ≥ 50%) after one year of treatment. Patients without psychiatric comorbidity exhibited better outcomes, without autonomic side-effects. Eight patients with panic disorder (always comorbid with other psychiatric disorders) showed the greatest number of side-effects during treatment with ziconotide. Emotional and cognitive symptoms of panic disorder are associated with autonomic symptoms resulting from parasympathetic activation. Dysfunction of both cholinergic and N-type calcium channel activity was found. A psychiatric disorder with cholinergic-noradrenergic system impairment could increase some side-effects of treatment with N-type calcium channel blockers.