Sirolimus

Hypersensitivity reactions, including anaphylactic/anaphylactoid reactions, angioedema, exfoliative dermatitis, and hypersensitivity vasculitis have been reported.

Has been reported; risk is increased in patients with elevated sirolimus levels and/or concurrent use with other drugs known to cause angioedema (eg, ACE inhibitors). Angioedema resolved following discontinuation or dose reduction in some cases.

Immunosuppressive agents, including sirolimus, increase the risk of infection. Immune suppression may also increase the risk of opportunistic infections including activation of latent viral infections (including BK virus-associated nephropathy), fatal infections, and sepsis. Prophylactic treatment for Pneumocystis jirovecii pneumonia (PCP) should be administered for 1 year post-transplant; prophylaxis for cytomegalovirus (CMV) should be taken for 3 months post-transplant in patients at risk for CMV. Progressive multifocal leukoencephalopathy (PML), an opportunistic CNS infection caused by reactivation of the JC virus, has been reported in patients receiving immunosuppressive therapy, including sirolimus. Clinical findings of PML include apathy, ataxia, cognitive deficiency, confusion, and hemiparesis; promptly evaluate any patient presenting with neurological changes; consider decreasing the degree of immunosuppression with consideration to the risk of organ rejection in transplant patients.

Cases of interstitial lung disease (ILD) (eg, pneumonitis, bronchiolitis obliterans organizing pneumonia [BOOP], pulmonary fibrosis) have been observed (some fatal); may be associated with pulmonary hypertension (including pulmonary arterial hypertension) and risk may be increased with higher trough levels. ILD may resolve with dose reduction or discontinuation of therapy.

May increase serum lipids (cholesterol and triglycerides). Use with caution in patients with hyperlipidemia. Monitor cholesterol/lipids; if hyperlipidemia occurs, follow current guidelines for management (diet, exercise, lipid lowering agents). Antihyperlipidemic therapy may not be effective in normalizing levels.

Use has been associated with an increased risk of fluid accumulation and lymphocele. Peripheral edema, lymphedema, ascites, and pleural and pericardial effusions (including significant effusions and tamponade) were reported; use with caution in patients in whom fluid accumulation may be poorly tolerated, such as in cardiovascular disease (heart failure or hypertension) and pulmonary disease.

Immunosuppressive agents, including sirolimus, may be associated with the development of lymphoma and other malignancies, including an increased risk of skin cancer; limit sun and ultraviolet light exposure; use appropriate sun protection.

Increased urinary protein excretion has been observed when converting renal transplant patients from calcineurin inhibitors to sirolimus during maintenance therapy. A higher level of proteinuria prior to sirolimus conversion correlates with a higher degree of proteinuria after conversion. In some patients, proteinuria may reach nephrotic levels; nephrotic syndrome (new onset) has been reported.

May increase serum creatinine and decrease GFR with long-term combination use of sirolimus and cyclosporine. Immunosuppressed patients are at an increased risk of BK viral-associated nephropathy which may impair renal function and cause graft loss; consider decreasing immunosuppressive burden if evidence of deteriorating renal function. Use with caution in patients concurrently taking medications which may alter renal function.

May be associated with wound dehiscence and impaired healing; use caution in the perioperative period. Patients with a body mass index (BMI) >30 kg/m2 are at increased risk for abnormal wound healing. Disease-related concerns:

Use with caution in patients with hepatic impairment; a reduction in the maintenance dose is recommended. Concurrent drug therapy issues:

Concurrent use with a calcineurin inhibitor (cyclosporine, tacrolimus) may increase the risk of calcineurin inhibitor-induced hemolytic uremic syndrome/thrombotic thrombocytopenic purpura/thrombotic microangiopathy (HUS/TTP/TMA).

Safety and efficacy of combination therapy with cyclosporine in high immunologic risk patients have not been studied beyond 12 months of treatment. Monitor renal function closely when combined with cyclosporine; consider dosage adjustment or discontinue in patients with increasing serum creatinine.

Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Immunosuppressants may affect response to vaccination. Therefore, during treatment with sirolimus, vaccination may be less effective. The use of live vaccines should be avoided. Special populations:

Sirolimus is not recommended for use in liver transplantation; studies indicate an association with an increased risk of hepatic artery thrombosis (HAT), graft failure, and increased mortality (with evidence of infection) in these patients when sirolimus is used in combination with cyclosporine and/or tacrolimus. Most cases of HAT occurred within 30 days of transplant.

Sirolimus is not recommended for use in lung transplantation. Bronchial anastomotic dehiscence cases have been reported in lung transplant patients when sirolimus was used as part of an immunosuppressive regimen; most of these reactions were fatal.

In renal transplant patients, de novo use without cyclosporine has been associated with higher rates of acute rejection. Sirolimus may delay recovery of renal function in patients with delayed allograft function. Dosage form specific issues:

Sirolimus tablets and oral solution are not bioequivalent, due to differences in absorption. Clinical equivalence was seen using 2 mg tablet and 2 mg solution. It is not known if higher doses are also clinically equivalent. Monitor sirolimus levels if changes in dosage forms are made.

Some dosage forms may contain propylene glycol; large amounts are potentially toxic and have been associated hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP, 1997; Zar 2007). Other warnings/precautions:

In renal transplant patients, sirolimus should be used in combination with cyclosporine (and corticosteroids) initially. Cyclosporine may be withdrawn in low-to-moderate immunologic risk patients after 2 to 4 months, in conjunction with an increase in sirolimus dosage. In high immunologic risk patients, use in combination with cyclosporine and corticosteroids is recommended for the first year. Adjustment of immunosuppressive therapy beyond 12 months should be considered based on clinical judgment.

Should only be used by physicians experienced in immunosuppressive therapy and management of transplant patients. Adequate laboratory and supportive medical resources must be readily available.

Sirolimus concentrations are dependent on the assay method (eg, chromatographic and immunoassay) used; assay methods are not interchangeable. Variations in methods to determine sirolimus whole blood concentrations, as well as interlaboratory variations, may result in improper dosage adjustments, which may lead to subtherapeutic or toxic levels. Determine the assay method used to assure consistency (or accommodations if changes occur), and for monitoring purposes, be aware of alterations to assay method or reference range and that values from different assays may not be interchangeable.