Drug interactions: a contribution to the rational use of synthetic and biological immunosuppressants.

Drug interaction is a clinical event in which the effects of a drug are altered by the presence of another drug, phytochemical drug, food, beverage, or any environmental chemical agent. The incidence of adverse reactions caused by drug interactions is unknown. This lack of information is compounded by not knowing the number of patients who are prescribed combinations of drugs that can potentially interact. Patients who will or will not experience an adverse drug interaction cannot be clearly identified. Those with multiple diseases, with kidney or liver dysfunction, and those on many drugs are likely to be the most susceptible. Patients with autoimmune diseases are at higher risk for drug interactions. In addition to representing a risk for the patient and jeopardizing the health care provided by professionals, drug interactions can increase dramatically health care costs. This review article approached the clinically relevant interactions between the most used drugs in rheumatology (except for non-steroidal anti-inflammatories and corticosteroids) aiming at helping rheumatologists to pharmacologically interfere in the disease processes, in the search for better outcomes for patients and lower costs with the complex therapy of chronic diseases they deal with.