Multi-center, randomized, double-blind, placebo-controlled, phase-3 Trial. Patients with a history of recurrent pericarditis who are being treated with an IL-1 blocker for at least 12 months, scheduled to be discontinued, will be approached for potential trial participation. Double-blind treatment will be initiated 10 - 16 days prior to the last scheduled dose of the IL-1 blocker and continued for 24 weeks. The objective is to assess whether patients remain free of pericarditis recurrence while receiving CardiolRx.