Prevention and management of the adverse effects associated with immunosuppressive therapy.

Advances in immunosuppressive therapy have resulted in significantly improved patient and graft survival after solid organ transplantation. However, increased use has brought attention to specific toxicities associated with the use of these agents. Corticosteroid therapy can result in a wide array of short and long term toxicities. Management of these effects has focused on alternate day and dosage reduction protocols. Myelosuppression, hepatotoxicity, alopecia and gastrointestinal adverse effects are associated with azathioprine and generally respond to a reduction in dosage or withdrawal. Cyclophosphamide myelosuppression is managed in a similar manner. Use of cyclosporin, while the mainstay of immunosuppressive therapy, is often complicated by several well documented adverse effects. Short and long term nephrotoxicity is often managed through pharmacokinetic dosing strategies as well as pharmacological intervention with calcium channel blockers, prostaglandin analogues, pentoxifylline and thromboxane antagonists. Cyclosporin-induced hypertension, hyperlipidaemia, hyperkalaemia and hyperuricaemia are generally responsive to appropriate dietary restrictions and pharmacological therapies. The adverse effects associated with polyclonal antilymphocyte agents (fever, chills, rash, arthralgias) occur in response to the administration of foreign protein substances but can be prevented by pretreatment with corticosteroids, diphenhydramine and paracetamol (acetaminophen). The administration of muromonab CD3 (OKT3) stimulates the release of cytokines resulting in potentially severe complications seen during the first 1 or 2 doses. Pretreatment with diphenhydramine, low dose corticosteroids and paracetamol as well as proper fluid management has reduced the incidence of this syndrome. However, agents such as high dose corticosteroids, indomethacin, pentoxifylline and anti-tumour necrosis factor monoclonal antibodies may further decrease the severity of cytokine-induced toxicity. Antimurine antibodies may also develop during muromonab CD3 therapy, potentially limiting the efficacy of this agent. However, continued concomitant immunosuppressive therapy has significantly reduced antibody formation. In summary, as newer agents are developed with narrow therapeutic windows, it will be critical to identify specific drug toxicity and to develop preventative and management therapeutic strategies.