9356. Sirolimus

Sirolimus is an immunosuppressant prescribed to patients who have undergone organ or tissue transplantation. Given the drug's high toxicity and the need for long-term treatment, it is essential to determine the optimal dose. Monitoring the drug concentration in the blood over time allows for safe dose adjustment.

The test is used to assess blood sirolimus levels, adjust the dose, and evaluate treatment effectiveness in patients receiving the medication following organ transplantation.

Sirolimus is an immunosuppressive drug derived from rapamycin. It acts by inhibiting the mTOR signaling pathway in immune system cells. This blocks the activation and proliferation of T and B lymphocytes, which is a key mechanism in preventing rejection of transplanted organs. Sirolimus may also be prescribed as adjunctive therapy for certain types of cancer.

Blood sirolimus level testing is performed exclusively in patients who are taking this medication as prescribed by a physician. The main purposes of monitoring are:

• prevention of transplant rejection (after kidney, heart, or other solid organ transplantation, maintaining a certain blood sirolimus level is necessary to ensure graft survival);
• monitoring the therapeutic concentration (sirolimus has a narrow therapeutic range, so regular measurement of its level helps the physician maintain the optimal concentration required for effective immunosuppression while preventing adverse effects);
• dose adjustment (depending on the test results and the patient's clinical condition, the physician may adjust the sirolimus dose to achieve the target level);
• assessment of interactions with other medications (because sirolimus is metabolized by liver enzymes, concomitant use of other medications may affect its blood concentration).

Sirolimus blood level testing should be performed according to the physician's recommendations regarding the timing of blood collection (usually immediately before the next dose). Regular monitoring of sirolimus levels is important for safe and effective treatment.

• To monitor the concentration of the medication in the blood (to determine an individualized dose after surgery in transplant medicine).
• For medical monitoring of the prescribed treatment regimen.
• For dose adjustment (in the event of adverse effects or signs of overdose, such as nausea, vomiting, diarrhea, loss of appetite, drowsiness, apathy, dizziness, etc.).
• To assess drug interactions when medications from several groups are taken concomitantly.

• Venous blood

In order to exclude factors that may affect the test results, we recommend to follow the preparation rules: