Open-label single-arm pilot study (NCT03896256; Cephalalgia 2021; PMID 34125442). Participants: n=6 adults (≥18 yr) with class IV refractory chronic migraine who had previously completed a 5-day lidocaine admission. No control arm, no randomisation. Intervention: 5-day continuous IV (R,S)-ketamine infusion starting at 10 mg/h, escalated every 4–6 h by 5–10 mg/h to intolerable adverse effects or 1 mg/kg/h; retrospective comparator data from prior lidocaine admission extracted from EMR. Plasma ketamine and metabolite concentrations (norketamine, DHNK, HNK isoforms) measured at baseline and 24/72/~120 h. EARLY_PHASE1; single centre; IRB-approved. Study start: March 2019.
Retrospectively collected standard treatment data from a prior 5-day lidocaine infusion hospitalization in the same patients.
Prospective 5-day continuous (R,S)-ketamine infusion.
Started at 10 mg/h and increased every 4-6 hours in increments of 5-10 mg/h up to the point of intolerable adverse effects or 1 mg/kg/h, whichever came first.