The Food and Drug Administration approved a new migraine drug on Thursday. Aimovig, known generically as erenumab, is the first drug in a new class of headache medicines. It’s been shown to stop migraine headaches before they start. The drug would be approved for patients who have tried other drugs and found no relief. In studies, it did not entirely prevent migraines, but reduced their frequency. FDA’s approval means the drug may soon be available under prescription. It should also be paid for by health insurance. The drug’s maker, Amgen, said U.S. list price is for the once monthly self-inject treatment will be $575 per month or $6,900 annually. Erenumab the first in a new class of drugs that block calcitonin gene-related peptide (CGRP), a molecule that transmits migraine pain signals during an attack. It’s a human monoclonal antibody -a targeted immune system protein. It’s formulated as an injection to provide long-lasting protection.