The trigemino-cerebrovascular system 1 1 2 4 Fig. 1 TG TNC  The trigemino-cerebrovascular reflex 5 6 7 8 1 9 Calcitonin gene-related peptide CGRP is a neuropeptide consisting of 37 amino acids and is predominantly expressed in the nervous system. It originates from the calcitonin gene encoding calcitonin and CGRP depending upon alternative splicing. 10 11 12 8 13 14 15 16 Triptans 1B/1D 8 1B 17 18 1B/1D 1B/1D 19 20 21 1B/1D 20 1B/1D 22 1B 1B/1D 1B/1D 23 24 25 26 1B 18 27 2A 2A 27 1B 28 29 Sensitization in migraine 30 31 32 31 33 34 36 37 37 CGRP receptors 38 39 40 41 42 43 45 46 47 48 50 47 51 47 CGRP receptor antagonists olcegepant and MK-0974 9 52 53 54 44 55 56 43 54 57 59 60 44 61 62 63 40 54 40 64 65 66 41 2 42 Fig. 2 MK-0974 MK-0974 p p left part 69 p 41 42  3 Fig. 3 MK-0974 MK-0974 p 69 42  42 60 67 68 67 −1 −1 67 69 p 2 p p p 3 p Concerning tolerability and safety, MK-0974 was generally well-tolerated. The reported side effects were mainly nausea, dizziness and somnolence, but the incidence of adverse experiences seemed to be comparable to the placebo group. In addition, there was no increase in adverse events with increasing dose. 69 Conclusion 41 69