Ziconotide Injection

(I) Clear Target Population and High Specificity

The product is indicated for patients with refractory cancer pain whose pain is not adequately controlled (Visual Analogue Scale, VAS ≥ 5) despite standardized opioid therapy, or who cannot tolerate opioid‑related adverse reactions (e.g., severe respiratory depression, intractable constipation, severe nausea and vomiting). It is particularly suitable for patients with concomitant neuropathic cancer pain, which accounts for more than 50% of refractory cancer pain cases.Neuropathic cancer pain has a complex pathogenesis, mainly caused by tumor invasion of nerves, chemotherapy‑ or radiotherapy‑induced nerve injury, and manifests as burning, stabbing, or electric‑shock‑like pain with low sensitivity to traditional opioids.

The product provides marked analgesia for this type of pain.Clinical studies show that intrathecal infusion of it effectively reduces pain scores and improves sleep and quality of life in patients with refractory cancer pain who are opioid‑tolerant or non‑responsive to opioids.A case series of 8 patients with refractory cancer pain (5 with concomitant neuropathic pain) reported that all patients achieved significant pain reduction within 3–5 days after intrathecal administration of ziconotide combined with morphine. One patient who failed to respond to fentanyl still achieved satisfactory pain control after resuming ziconotide therapy, confirming its value in patients unresponsive to opioids.

(II) Significant Analgesic Efficacy and Non‑Addictive Properties

The analgesic potency of it is comparable to that of morphine and even superior in some patients, with a dose‑dependent analgesic effect; optimal analgesia can be achieved through slow dose titration. Multiple clinical studies confirm that intrathecal infusion of it reduces pain scores by more than 30% in patients with refractory cancer pain, with pain relief rates exceeding 70% in some individuals. In a randomized, double‑blind, placebo‑controlled clinical trial involving 169 patients with severe chronic pain (including those with refractory cancer pain), ziconotide treatment reduced the mean VAS score by 31.2%, compared with only 6.0% in the placebo group, representing a statistically significant difference (P ≤ 0.001).

Compared with opioids, the most prominent advantage of ziconotide injection is its lack of addiction potential. It does not act on opioid receptors, does not induce physical or psychological dependence, and does not cause withdrawal symptoms, allowing safe long‑term use. This feature is especially critical for advanced cancer patients requiring prolonged analgesia, as it avoids additional suffering and treatment burden associated with drug addiction. Furthermore, the drug does not cause respiratory depression, providing a higher safety profile for patients with refractory cancer pain and concurrent respiratory insufficiency, with no risk of drug‑induced respiratory failure.

(III) Synergistic Combination with Other Analgesics to Enhance Therapeutic Outcomes

In clinical management of refractory cancer pain, monotherapy often fails to achieve ideal analgesia, making combination therapy a common strategy. The product can be used in combination with opioids, local anesthetics (e.g., bupivacaine), and other analgesics to produce synergistic analgesia, reduce individual drug dosages, and lower the incidence of adverse reactions.

Clinical studies demonstrate that low‑dose ziconotide combined with intrathecal morphine rapidly controls opioid‑refractory cancer pain while reducing morphine dosage and its associated adverse reactions such as constipation and respiratory depression. A case series of 8 patients with refractory cancer pain reported that all patients had failed prior intrathecal morphine plus bupivacaine therapy, but achieved effective pain control after add‑on ziconotide therapy initiated at 0.5–1.0 μg/day and titrated upward by 0.5 μg every 4–7 days (maximum dose ≤ 10 μg/day). Morphine dosages were also reduced, confirming the efficacy and safety of combination therapy.

(I) Clinical Research Progress

In recent years, numerous domestic and international clinical studies have investigated ziconotide injection for refractory cancer pain, further validating its analgesic efficacy and safety. A multicenter, randomized, double‑blind, placebo‑controlled study enrolled 457 patients with severe chronic pain (including refractory cancer pain), randomized to ziconotide (268 patients) or placebo (189 patients) with slow dose titration for 21 days.

The ziconotide group showed a mean pain score reduction of 12%, compared with 5% in the placebo group (statistically significant), with a markedly lower incidence of adverse reactions than with rapid titration.Real‑world evidence also supports its clinical use. An 18‑month prospective, multicenter observational study (PRIZM Registry) included 93 patients with severe chronic pain treated with intrathecal ziconotide. Assessment via the Numeric Pain Rating Scale (NPRS) revealed significant pain reduction at 12 weeks and favorable long‑term safety, confirming its value in prolonged analgesia.

Additionally, studies on neuropathic cancer pain show ziconotide provides superior relief compared with traditional opioids, offering a more effective option for this patient population.

Ongoing clinical research is exploring optimized dosing regimens, including combination strategies and individualized dose titration, to further improve analgesia and minimize adverse reactions. Studies in special populations (e.g., elderly patients, those with hepatic or renal impairment) are also underway to support personalized clinical therapy.

(II) Application Prospects

With rising demand for refractory cancer pain management, the product, as a novel non‑opioid analgesic, has broad clinical prospects. On the one hand, its unique mechanism makes it a vital therapeutic option for patients with opioid tolerance or non‑response, filling a clinical gap and improving quality of life. On the other hand, its non‑addictive and non‑respiratory‑depressant properties reduce adverse events and treatment risks, especially for patients with respiratory insufficiency or high addiction risk.As clinical research advances, it will likely be further validated for specific subtypes of refractory cancer pain, with optimized regimens and expanded indications.

Meanwhile, wider adoption and standardization of intrathecal drug delivery will increase its clinical utilization, benefiting more patients. Development of long‑acting formulations will also be a future research direction, aiming to reduce dosing frequency and improve patient convenience and adherence.

Notably, it has current clinical limitations, including a relatively complex administration route (requiring intrathecal infusion), a high incidence of adverse reactions, and high cost, which restrict its widespread use. Future innovations in technology and cost control will address these barriers, improve clinical accessibility, and benefit more patients with refractory cancer pain.