 The screening visit can be performed either before an active cluster period or once the cluster period has already started. If the subject agrees to participate, the study doctor will determine if they are eligible for this study. The subject will be asked about their headache history, and medical history including all medications they are currently taking. A brief physical examination and neurologic examination will be performed and vital signs pulse and blood pressure will be measured. If the subject is a woman who is capable of bearing children, they will be asked to provide a urine sample for a routine pregnancy test. A blood sample approximately 2 teaspoons will also be obtained. Blood samples will be taken for a liver function test LFT, complete blood count CBC with differential, chemistry profile, prothrombin time PT and partial thromboplastin time PTT.If the screening visit is the same day as the first treatment visit, this blood work will be sent for immediate analysis. The results must be reviewed and approved by the study physician prior to the subject being administered study medication. 