The present invention relates a composition for treating rheumatic diseases. The composition comprises a compound having the formulawherein Ra is selected from —OCH3, —OCH2CH3, —CH3, —CH2CH3, —CCCH3, —CHCH—CH3, or CH2—CHCH2; and one or more anti-rheumatic agents. A method of using the composition for treating rheumatic diseases in humans and animals is also disclosed.