When Does Galcanezumab Start Working for Headache?
Galcanezumab begins reducing migraine frequency within the first day after injection, with statistically significant reductions in migraine headache days evident from day 1 and maintained throughout treatment. 1
Onset of Effect
Galcanezumab demonstrates rapid onset, with a lower percentage of patients experiencing migraine headache on the first day after injection compared to placebo. 1
Using sequential analysis methodology, galcanezumab achieved and subsequently maintained statistical superiority to placebo starting from the earliest measured time point in phase 3 trials. 1
The mean reduction in monthly migraine headache days was 4.1-4.3 days with galcanezumab 120 mg compared to 1.0-2.3 days with placebo, with this difference evident early in treatment. 2, 3
Clinical Significance Timeline
Guidelines recommend assessing efficacy of CGRP monoclonal antibodies like galcanezumab only after 3-6 months of treatment, as full therapeutic effect develops over time. 4
Patients should be discouraged from abandoning treatment in the early stages based on apparent inefficacy, as the response continues to build over several weeks to months. 4
Treatment response should be formally evaluated 2-3 months after initiation, with regular follow-up every 6-12 months thereafter. 4
Maintenance of Response
Galcanezumab provides sustained maintenance of effect throughout the treatment period, with at least 50% response rates maintained at the individual patient level. 1
In long-term studies, mean reductions in monthly migraine headache days over 12 months were 5.6 days (120 mg dose) and 6.5 days (240 mg dose). 5
Both 120 mg and 240 mg doses demonstrated comparable efficacy, with the 120 mg dose associated with lower adverse event rates. 6
Important Clinical Considerations
The rapid onset distinguishes galcanezumab from traditional oral preventive medications (beta-blockers, topiramate, amitriptyline), which typically require 2-3 months to demonstrate efficacy. 4
Upon treatment cessation, galcanezumab effect gradually diminishes over a 4-month post-treatment period without signs of rebound headache. 1
Galcanezumab is positioned as third-line preventive therapy after failure of first-line (beta-blockers, topiramate, candesartan) and second-line (amitriptyline, flunarizine) agents. 4