Any agent that inhibits calcineurin (protein phosphatase 3; PPP3), a serine/threonine protein phosphatase dependent on calcium and calmodulin, with immunosuppressant activity. Inhibition of calcineurin prevents dephosphorylation of the transcription factor nuclear factor of activated T-cells, cytoplasmic (NFATc), which prevents its translocation to the nucleus and the subsequent induction of the expression of interleukin-2 (IL-2). This prevents IL-2-mediated proliferation and activation of T-cells, and T-lymphocyte-mediated immune responses.