Ziconotide (Prialt)

Ziconotide is a synthetic version of omega-conotoxin MVIIA from Conus magus venom. Developed as SNX-111 and marketed as Prialt, it received US approval in 2004 for severe chronic pain requiring intrathecal treatment.

It selectively blocks N-type voltage-gated calcium channels on pain-sensing terminals in the spinal dorsal horn. Reduced neurotransmitter release interrupts upward pain transmission. This differs from opioid receptor signaling and does not produce the same respiratory-depression or tolerance pattern.

Because bloodstream delivery does not readily provide the required central access, an implanted or external microinfusion pump delivers it directly into cerebrospinal fluid. It must never be administered intravenously. A controlled refractory cancer/AIDS-pain trial found substantially greater pain-score reduction than placebo. The therapeutic window is narrow, requiring cautious slow dose adjustment.

Prialt is FDA-approved for severe chronic pain when intrathecal treatment is warranted and other therapies are ineffective or intolerable, including intrathecal morphine. Pain specialists manage the pump and treatment.

A boxed warning addresses severe psychiatric symptoms and neurological impairment. A history of psychosis is a contraindication; approval is not a general wellness-pain or self-injection indication.

Common effects include dizziness, nausea, confusion, memory difficulty, gait disturbance, drowsiness and involuntary eye movements. Severe depression/suicidal thoughts, hallucinations and neurological impairment require close monitoring and cessation when serious signs develop.

Contaminated pumps or catheters can cause meningitis or other infections. These device, psychiatric and neurological risks are material parts of the product’s specialist-use context.