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Sirolimus is an immunosuppressant drug that is prescribed for someone who receives a donor organ in an organ transplant procedure. Also known as rapamycin, this drug is a derivative of a bacterial species called Streptomyces hygroscopicus. Sirolimus is most often used to prevent organ rejection in people who undergo a kidney transplant. It is often used in preference to other immunosuppressant drugs because it has a lower risk of kidney toxicity after long-term use.
An immunosuppressant is a drug that suppresses the immune system. These drugs are prescribed for a person who receives a donor organ to ensure that his or her immune system does not mount an attack that might destroy the organ. The immune system attacks donor organs because of differences in cells from the donor organ compared to cells of the recipient.
Sirolimus works by preventing the immune response to a cytokine called interleukin-2. Cytokines are molecules that act as chemical signals, providing instructions to the cells of the immune system. Interleukin-2 is a vital cytokine that is essential in activating T and B lymphocytes, both of which can contribute to an organ-destroying immune response.
Possible side effects of sirolimus include joint, stomach, and back pain; upset stomach; diarrhea; constipation; vomiting; weight gain; swelling of hands, legs, ankles or feet; difficulty falling asleep; fever; and rash. These symptoms usually are temporary but can be of longer duration. Anyone who experiences these symptoms should discuss them with his or her doctor. Serious symptoms include unexplained bruising or bleeding, difficulty breathing, coughing, frequent urination, vision disturbances, unusually fast or slow heartbeat and mood changes. Anyone with one or more of these symptoms should speak with his or her doctor as soon as possible.
Because sirolimus suppresses the immune system, anyone taking this medication has an increased risk of infection and is more likely to suffer severe symptoms of infection. The medication can slow the healing of wounds, increase blood cholesterol levels and increase blood pressure. In addition, taking this medication increases the risk of lymphoma, skin cancer and certain other types of cancer. Symptoms such as changes in pigmented skin spots or moles, swollen lymph nodes, unexplained weight loss, fever and night sweats should be discussed with a doctor.
People who take this medication should try to avoid contact with people who have infectious diseases, including colds and the flu, because this medication causes an increased susceptibility to infection. Vaccinations should be carried out only with a doctor’s consent. In particular, live vaccinations must be avoided, because they have the potential to cause serious infection. Finally, direct sunlight should be avoided as much as possible, and sun protection should be used outdoors, because of the increased risk of skin cancer.