American Board of Surgery Qualifying Exam (ABS QE) Practice Test

Which immunosuppression agent is associated with seizures and tremors?

1. Sirolimus

2. FK506 (tacrolimus)

3. Mycophenolate mofetil

4. Azathioprine

The correct answer is: FK506 (tacrolimus)

FK506, also known as tacrolimus, is an immunosuppressive agent commonly used in transplant recipients to prevent organ rejection. This drug is a calcineurin inhibitor, which works by inhibiting T-cell activation and proliferation. One of the key side effects associated with tacrolimus is its neurotoxicity, which can manifest as neurological symptoms such as seizures and tremors. The mechanism through which tacrolimus causes these symptoms is not fully understood, but it is thought that it may alter neurotransmitter levels or affect neuronal function in some individuals. This spectrum of neurological effects is significant because it requires careful monitoring of drug levels to avoid toxicity, especially since tacrolimus has a narrow therapeutic window. Other immunosuppressants mentioned do not typically present seizures and tremors as notable side effects. For example, sirolimus is more commonly associated with hyperlipidemia and pneumonitis than with neurological complications. Mycophenolate mofetil is primarily linked to gastrointestinal side effects and blood dyscrasias, while azathioprine can cause bone marrow suppression but is not known for causing seizures or tremors. Thus, in the context of the question, tacrolimus is distinctly associated with neurological symptoms, making it the correct answer