Dopamine D2–Receptor Imaging With 123I-Iodobenzamide SPECT in Migraine Patients Abusing Ergotamine: Does Ergotamine Cross The Blood Brain Barrier?

Two migraine patients were studied by in vivo SPECT using the dopamine D2–receptor specific radioligand 123I-3–iodo-6–methoxybenzamide (123I-IBZM) during ergotamine abuse and after withdrawal. Results were compared with 15 healthy controls. Striatum/cerebellum and striatum/occipital cortex ratios of count rate density were calculated as a semiquantitative measurement for striatal dopamine D2–receptor binding potential. No differences were found in striatal uptake of 123I-IBZM between healthy controls and the patients when on or off ergotamine. Preliminary evidence suggests that ergotamine may not occupy striatal dopamine D2–receptors to a large extent and thus may not cross the blood brain barrier in large quantities.