- Minocycline is an antibiotic belonging to the group of the Tetracyclines. It is applied in treating bacterial infections and skin disorders (acne), but there are studies that prove a good effect on the inflammatory changes with rheumatoid arthritis (O´Dell, 1999; O´Dell et al., 2001; Pillemar et. al., 1997). In a four-years-lasting double-blind-placebo-controlled study it could be demonstrated that Minocycline represents an effective therapy for the seropositive rheumatoid arthritis. Moreover, during the long term therapy only a low side effect rate was observed (O´Dell et al., 1999; Langevitz et al., 2000; Alarcon, 2000).