Inclusion Criteria:

• Must have either completed the Double-Blind Phase of CAPSS-271 or discontinued the Double-Blind Phase of CAPSS-271 due to lack of efficacy after a minimum of 2 weeks of maintenance treatment.
• Must continue to meet the specific inclusion criteria outlined in CAPSS-271.
• Female subjects must be premenarchal, surgically sterile (hysterectomy, tubal ligation or otherwise incapable of pregnancy); or practicing an effective method of birth control (e.g., intrauterine device, double-barrier method, male partner sterilization) at study entry and throughout the study; or hormonal contraceptives for at least a 3-month period prior to the start of the study and throughout the study, or be practicing abstinence and agree to continue abstinence or to use an acceptable method of contraception (as listed above) should sexual activity commence. In addition, female subjects of childbearing potential must have a negative urine pregnancy test at Open-Label Visit 1 (Day 1).
• Must be able to read and comprehend written instructions and be willing to complete all headache records and questionnaires as required by the protocol.
• After full explanation of the study, subjects, or their parent/legally authorized representative(s), must demonstrate their willingness to participate by signing an informed consent form. If applicable, pediatric subjects capable of giving assent must sign the assent form.

Exclusion Criteria:

• Subjects who have developed a more painful condition than their headache pain.
• Subjects taking any of the prohibited concomitant medications (See Concomitant Medications section).
• Subjects who are pregnant.
• Subjects with liver function tests ³ 2 times the upper limit of the normal range.
• In the investigator’s opinion, subjects with poor compliance during the CAPSS-271 study