The generic name of this medication is daclizumab and brand name is Zenapax. The active ingredient of this medication is daclizumab and inactive ingredients include ammoniomethacrylate copolymer. This medication is used to prevent the body from rejecting a transplanted kidney. Daclizumab is usually used as part of a treatment regimen including other medications.

Daclizumab (Zenapax) is a humanized monoclonal antibody to the IL-2Rα receptor of T cells. It is used to prevent rejection in organ transplantation, especially in kidney transplants. It is given in multiple doses, the first 1 hour before the transplant operation and 5 further doses given at two week intervals after the transplant. These saturate the receptors and prevent T cell activation and thus prevent formation of antibodies against the transplant. Like the similar drug basiliximab, daclizumab reduces the incidence and severity of acute rejection in kidney transplantation without increasing the incidence of opportunistic infections. Daclizumab can also be used in place of a calcineurin-inhibitor (ciclosporin or tacrolimus) in the early phase after kidney transplantation when the kidney is recovering and vulnerable to calcineurin-inhibitor toxicity. This has been shown to be beneficial in non-heart beating donor kidney transplantation. In the United Kingdom, the National Institute for Health and Clinical Excellence has recommended its use be considered for all kidney transplant recipients. In 2006 it began a Phase II clinical trial that finished in 2007 as a possible Multiple Sclerosis treatment. Participants were nine patients with multiple sclerosis not controlled with interferon. Daclizumab was effective in reducing lesions and improving clinical scores. Daclizumab has also been used to arrest the progression of autoimmune diseases, especially birdshot retinochoroidopathy.