Hypersensitivity. Discontinue use if progressive multifocal leukoencephalopathy, significant liver injury, posterior reversible encephalopathy syndrome is suspected. Not to be initiated in patients w/ active acute or chronic infection. Macular edema; basal cell carcinoma; lymphoma; Kaposi's sarcoma & cryptococcal infections; MS relapses w/ tumefactive demyelinating lesions. Severe increase in disability accompanied by multiple new lesions after discontinuation; decreased lymphocyte counts for up to 2 mth following last dose. Obtain cardiac evaluation in patients w/ preexisting conditions (eg, ischemic heart disease, history of MI, cardiac arrest, symptomatic bradycardia, or recurrent syncope; CHF, cerebrovascular disease, uncontrolled HTN, severe untreated sleep apnea, AV block, SA heart block) prior to treatment. Perform ECG prior to 1st dose & at end of 6-hr observation period; recent CBC; cancer screening including Pap tests in patients on immunosuppressives; spirometric evaluation of resp function & diffusion lung capacity of carbon monoxide during therapy; ophth exam prior to & regularly in patients w/ history of uveitis & DM. Periodic skin exam. Monitor BP during treatment. Consider HPV vaccination prior to initiation. Varicella zoster virus vaccination of Ab -ve patients & postpone initiation for 1 mth. Limit exposure to sunlight & UV light. Prior & concomitant use w/ antineoplastics, immunosuppressives or immune-modulating therapies. Severe hepatic impairment. Women of childbearing potential should use effective contraception during & for 2 mth after last dose. Pregnancy. Not to be used during lactation. Ped <10 yr. Elderly ≥65 yr.