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Galcanezumab (Emgality) is one of the three injectable monoclonal antibodies approved for the prevention of migraines. Pharmacological studies show that it takes up to a week for these drugs to reach their highest concentration. However, it does not mean that it takes a week for them to start helping. Many of my patients report feeling better within a day. A new study of galcanezumab indicates that such a rapid onset of action is not just due to the placebo effect.
The authors analyzed the results of two large studies of patients with episodic migraines that were submitted to the FDA to gain its approval. The first study enrolled 858 patients and the second, 915. Patients were given monthly injections of galcanezumab 120 mg (with 240 mg loading dose) or 240 mg or placebo for up to 6 months. In both studies, the onset of effect was present the day after the injection.
I do tell my patients that they might start feeling better the day after they receive their first injection (the initial dose of two 120 mg injections), but it is more likely that they will begin to improve within a week or even later. Some patients notice only minimal relief even at the end of the first month and require 2 or 3 monthly shots before any significant improvement occurs. This is true for all three injectable CGRP monoclonal antibodies.
Vyepti, the fourth drug in this family, which was just approved and will be available in a month, is given intravenously. This may result in an even faster onset of action.
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