Peptide Schedule
Ziconotide (Prialt)25 residuesCKGKGAKCSRLMYDCCTGSCRSGKCEach bubble = one amino acid. Size = residue mass. Color = chemical class.Ziconotide (Prialt)
Benefits
About Ziconotide (Prialt)
Ziconotide is a synthetic 25-amino-acid peptide identical to omega-conotoxin MVIIA, a naturally occurring toxin found in the venom of the Pacific marine cone snail Conus magus. First approved by the FDA in December 2004 under the brand name Prialt, it represents the first-in-class selective N-type voltage-gated calcium channel (Cav2.2) blocker approved for clinical use. It is indicated for the management of severe chronic pain in patients for whom intrathecal therapy is warranted and who are intolerant of or refractory to other treatment options, including systemic analgesics, adjunctive therapies, and intrathecal morphine.\n\nThe drug works by selectively and reversibly binding to N-type voltage-gated calcium channels (Cav2.2) located on primary afferent nociceptive nerve terminals in the superficial layers (laminae I and II) of the dorsal horn of the spinal cord. By blocking calcium influx through these channels, ziconotide prevents the release of pro-nociceptive neurotransmitters — including glutamate, calcitonin gene-related peptide (CGRP), and substance P — thereby interrupting pain signal transmission at the spinal level. Unlike opioids, ziconotide does not bind to opioid receptors and does not produce tolerance, physical dependence, or respiratory depression.\n\nThree pivotal randomized, double-blind, placebo-controlled trials established its efficacy. Study 301 (Rauck et al., 2006) demonstrated statistically significant pain reduction in 220 patients with severe chronic pain (14.7% vs 7.2% improvement; P=0.036) with a slow titration protocol. Study 96-002 (Wallace et al., 2006) showed a 31.2% mean reduction in pain scores versus 6.0% for placebo in 255 patients with chronic nonmalignant pain using a rapid titration. A long-term open-label extension (Wallace et al., 2008) with 644 patients demonstrated sustained efficacy over 350 patient-years of exposure.\n\nZiconotide carries a Black Box Warning for severe psychiatric symptoms and neurological impairment, including cognitive impairment, hallucinations, psychosis, and changes in mood or consciousness. It is contraindicated in patients with a preexisting history of psychosis. Depression with risk of suicide has been reported. Despite these serious warnings, ziconotide fills a critical therapeutic niche as a non-opioid option for patients with the most severe, refractory chronic pain — particularly those who have failed or cannot tolerate intrathecal opioids.
Who Should Consider Ziconotide (Prialt)
- Patients with severe chronic pain refractory to systemic analgesics and adjunctive therapies
- Individuals intolerant of or refractory to intrathecal morphine
- Patients with severe neuropathic pain (e.g., from spinal cord injury, failed back surgery syndrome)
- Cancer patients with intractable pain who have failed conventional analgesic ladders
- Patients requiring non-opioid intrathecal analgesia due to opioid tolerance or adverse effects
- Adults with chronic pain who already have or are candidates for implanted intrathecal pump systems
How Ziconotide (Prialt) Works
Ziconotide is a synthetic form of omega-conotoxin MVIIA, a 25-amino-acid peptide stabilized by three disulfide bonds (Cys1-Cys16, Cys8-Cys20, Cys15-Cys25) that confer a rigid three-dimensional structure essential for its pharmacological activity. It acts as a potent and highly selective blocker of N-type voltage-gated calcium channels (Cav2.2), which are densely expressed on primary afferent nociceptive nerve terminals in the superficial laminae (I and II) of the spinal cord dorsal horn.\n\nWhen delivered intrathecally, ziconotide binds to the extracellular surface of the Cav2.2 alpha-1B subunit pore, physically occluding calcium ion flow. This blockade prevents the calcium-dependent vesicular release of excitatory and pro-nociceptive neurotransmitters from presynaptic terminals, including glutamate, calcitonin gene-related peptide (CGRP), and substance P. By interrupting neurotransmitter release at the first central synapse in the pain pathway, ziconotide produces potent analgesia at the spinal level without engaging supraspinal circuits.\n\nCritically, ziconotide has no affinity for opioid receptors (mu, delta, or kappa), adrenergic receptors, serotonin receptors, dopamine receptors, or GABA receptors. This receptor selectivity explains the absence of opioid-like side effects such as respiratory depression, constipation, and tolerance development. Unlike opioids — which modulate pain through inhibitory G-protein signaling and often lose efficacy over time due to receptor desensitization — Cav2.2 channel blockade by ziconotide does not lead to pharmacological tolerance, as there is no receptor downregulation or compensatory upregulation pathway. The narrow therapeutic window is attributed to Cav2.2 channels also being present in supraspinal regions involved in cognition, mood, and motor function, which accounts for the dose-limiting neuropsychiatric side effects.
What to Expect
Intrathecal infusion begins at 2.4 mcg/day (0.1 mcg/hour). Steady-state CSF concentration is approximated within ~24 hours (approximately five half-lives). Some patients may notice early pain relief within hours. Common initial side effects include dizziness, nausea, and somnolence.
Gradual dose escalation in increments of no more than 2.4 mcg/day, no more than 2-3 times per week. Pain relief increases with dose. Cognitive side effects (confusion, memory impairment) and psychiatric symptoms may emerge during this period — careful monitoring is essential.
Most patients reach an effective maintenance dose, typically between 4.8-14.4 mcg/day in clinical practice. In pivotal trials, mean effective doses ranged from 6.9-9.6 mcg/day. CK levels should be monitored every other week.
Sustained analgesia at stable dose. Unlike opioids, tolerance does not develop. Ongoing monitoring for insidious cognitive changes, mood disturbances, and psychiatric symptoms is critical. CK monitoring transitions to monthly.
Long-term maintenance with continued efficacy. Pump refills every 1-3 months depending on concentration and flow rate. Long-term open-label data shows sustained pain relief over 350+ patient-years. Periodic neuropsychological assessment is recommended.
Dosing Protocol
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 2.4mcg | Daily |
| Moderate | 9.6mcg | Daily |
| Aggressive | 19.2mcg | Daily |
Note: Ziconotide is an FDA-approved non-opioid analgesic delivered exclusively via continuous intrathecal infusion using an implanted or external microinfusion pump. It is NOT suitable for subcutaneous, intravenous, or epidural administration. Supplied as a pre-filled solution (25 mcg/mL or 100 mcg/mL) — no reconstitution with bacteriostatic water is needed. Dosing in the calculator reflects total daily intrathecal infusion in mcg/day (delivered continuously over 24 hours, not as a single bolus). The recommended starting dose is 2.4 mcg/day (0.1 mcg/hour), with slow upward titration of no more than 2.4 mcg/day increases, no more frequently than 2-3 times per week, up to a maximum of 19.2 mcg/day (0.8 mcg/hour). BLACK BOX WARNING: Severe psychiatric symptoms and neurological impairment may occur. This is a prescription medication that must be administered under direct medical supervision by a physician experienced with intrathecal drug delivery systems.
How to Inject Ziconotide (Prialt)
Ziconotide must be administered as a continuous intrathecal infusion using either a Medtronic SynchroMed EL or SynchroMed II implantable pump, or an external microinfusion device with catheter. It must NOT be administered by any other route (IV, epidural, SC). The recommended starting dose is 2.4 mcg/day (0.1 mcg/hour). Titrate upward in increments of no more than 2.4 mcg/day (0.1 mcg/hour), no more than 2-3 times per week, based on pain relief and tolerability. Maximum recommended dose is 19.2 mcg/day (0.8 mcg/hour). The 25 mcg/mL concentration may be administered undiluted. The 100 mcg/mL concentration must be diluted with preservative-free normal saline prior to use in external pumps. Pump refills must be performed by qualified healthcare providers under sterile conditions to minimize meningitis risk. Monitor CK levels every other week for the first month, then monthly. Assess cognitive function, psychiatric status, and neurological signs at every visit. Dose reductions or discontinuation should be considered if clinically significant psychiatric symptoms, cognitive impairment, or CK elevation (above 3x ULN) develop.
Cycling Protocol
Ziconotide is used as continuous long-term therapy delivered via intrathecal pump, not cycled. Treatment is maintained indefinitely as long as the patient derives analgesic benefit and tolerates the medication. Dose adjustments are made gradually — no more than 2.4 mcg/day increases, no more frequently than 2-3 times per week. If discontinued, no taper is required as there is no physical dependence or withdrawal syndrome. Treatment may be interrupted or discontinued if psychiatric symptoms, cognitive impairment, or elevated CK levels occur.
Pharmacokinetics
Source: FDA prescribing information; Wermeling D et al. J Clin Pharmacol. 2003;43(6):624-36. PMID: 12817525 (median 4.5 h in CSF, range 2.9-6.5 h)
Loading the interactive decay curve.
Side Effects
BLACK BOX WARNING: Severe psychiatric symptoms and neurological impairment may occur during treatment with ziconotide. The most commonly reported adverse events in clinical trials were dizziness (47%), nausea (30%), confusion (33%), headache (15%), somnolence (22%), nystagmus (8%), memory impairment (7-22%), and abnormal gait (14%). Psychiatric adverse events are a major concern: hallucinations occurred in 12% of patients, paranoid reactions in 3%, hostility in 2%, delirium in 2%, psychosis in 1%, and manic reactions in 0.4%. Depression with risk of suicide has been reported. Cognitive impairment including difficulty with word-finding and memory is common and may be insidious in onset. Other reported effects include asthenia, urinary retention, visual disturbances (amblyopia, abnormal vision), fever, postural hypotension, and elevated creatine kinase (CK) levels. Most adverse events are dose-related and may resolve with dose reduction or drug discontinuation. Meningitis (both chemical and bacterial) has been reported in patients using external microinfusion devices.
Contraindications
- Preexisting history of psychosis (FDA-labeled contraindication)
- Hypersensitivity to ziconotide or any component of the formulation
- Active infection at the microinfusion injection site
- Uncontrolled bleeding diathesis or concurrent anticoagulation with spinal canal risk
- Spinal canal obstruction that impairs CSF circulation
- Active suicidal ideation or severe untreated depression
- Pregnancy (Category C — potential for fetal harm based on animal studies)
- Breastfeeding (unknown excretion in human milk; not recommended)
Drug Interactions
- CNS depressants (benzodiazepines, sedatives, antiepileptics): Additive CNS depression including increased dizziness, confusion, and somnolence; monitor closely and consider dose reduction of concomitant agents
- Intrathecal opioids: Combination not studied in controlled trials and not recommended; potential for additive CNS effects
- Neuroleptics/antipsychotics: Increased risk of psychiatric adverse events and depressed consciousness; use with caution
- Intrathecal clonidine or bupivacaine: May potentiate hypotensive effects of ziconotide
- Drugs that elevate CK (statins, fibrates): May complicate monitoring of CK levels, which is recommended during ziconotide therapy
- Diuretics: Patients taking concomitant diuretics may be at higher risk of depressed levels of consciousness
Storage & Stability
Molecular Profile
Related Peptides
References
- Pharmacokinetics and pharmacodynamics of intrathecal ziconotide in chronic pain patientsPubMed 12817525
- A randomized, double-blind, placebo-controlled study of intrathecal ziconotide in adults with severe chronic painPubMed 16716870
- Intrathecal ziconotide in the treatment of chronic nonmalignant pain: a randomized, double-blind, placebo-controlled clinical trialPubMed 22151630
- Intrathecal ziconotide for severe chronic pain: safety and tolerability results of an open-label, long-term trialPubMed 18227325
- Ziconotide: a review of its pharmacology and use in the treatment of painReview
- PRIALT (ziconotide intrathecal infusion) — FDA Prescribing InformationFDA Label