Using cyclophosphamide in inflammatory rheumatic diseases

Cyclophosphamide (CYC), primarily introduced into clinical practice as an anti-cancer substance, is a potent immunosuppressive drug. Today, it is used in a number of organ- or life -threatening autoimmune diseases such as systemic vasculitides or connective tissue diseases. While being effective, CYC has a small therapeutic index and is associated with significant toxicity. CYC has been used in oncology in a variety of diseases and a lot of data has been derived from this area. This knowledge is often extrapolated to the rheumatologic settings. However, besides some similarities substantial differences between these two specialties considering the underlying diseases as well as the kind of application of the drug exist. The aim of the present review is to describe the general characteristics of the use of CYC from the rheumatologist's point of view, including pharmacologic and pharmacokinetic properties, drug interactions, toxicity and possible preventive and/or therapeutic measures; all of which are important to consider when using this particular drug in the treatment of inflammatory rheumatic diseases.