Which combination of immunosuppressive drugs should be avoided due to their similar mechanism of action?

The combination of tacrolimus, cyclosporine, and prednisone should be avoided due to their overlapping mechanisms of action as immunosuppressants. Both tacrolimus and cyclosporine belong to the class of calcineurin inhibitors, which work by inhibiting T-cell activation and proliferation. This dual use increases the risk of toxicity and adverse effects, including nephrotoxicity and increased susceptibility to infections, due to the excessive immunosuppression that can occur when both drugs are used together.

Prednisone, a corticosteroid, is often used alongside other immunosuppressants to enhance immunosuppression. While it has a different mechanism of action, using it in conjunction with two calcineurin inhibitors is not advisable because it does not mitigate the risks associated with the overlapping effects of the calcineurin inhibitors. Instead, it simply adds to the overall immunosuppressive burden on the patient.

In contrast, the other combinations listed include drugs that either have different mechanisms or a better-balanced immunosuppressive strategy, thus making them safer options.