Side by side

1. 1.Blocks N-type (Cav2.2) voltage-gated calcium channels on primary pain-sensing neurons.
2. 2.Prevents calcium influx and the release of substance P and glutamate in the dorsal horn.
3. 3.Reduces pain signalling without acting on opioid receptors.
4. 4.Must be delivered into cerebrospinal fluid because it cannot cross the blood-brain barrier.
5. 5.Has a narrow therapeutic window, with psychiatric and neurological effects close to the useful dose.

• Severe chronic pain refractory to other treatment
• Neuropathic and cancer-related pain in intrathecal pump trials
• Opioid-refractory pain in patients already receiving intrathecal therapy

• Clinically meaningful pain reduction in a subset of patients in randomised trials
• No opioid tolerance or respiratory depression
• Neuropsychiatric effects such as confusion, hallucinations and mood change
• Requires slow titration over weeks

• Dizziness and confusion
• Nausea and vomiting
• Nystagmus and abnormal gait
• Memory impairment
• Hallucinations and mood change
• Meningitis with pump complications
• Suicidal ideation reported

Research context only - an implanted intrathecal pump therapy managed by a pain specialist. Titration starts at 2.4 micrograms per day and increases slowly, with a maximum of 19.2 micrograms per day in most patients and no bolus dosing; trials measured pain intensity and adverse events over 3 to 6 weeks of titration.

Research context only