1. Subject has a history of frequent headache or other painful conditions, other than that associated with PHN, within the past 30 days that has required or is expected to require the additional use (beyond stable daily doses) of prescription or over the counter pain relief medication, such as non-steroidal anti-inflammatory agents, including COX-2 inhibitors, systemic opiates or derivatives, or acetaminophen more than 2 times per week during the study. Concurrent medications and stable dose requirements are listed in Table 3.