Moderate and usually reversible reduction in all three blood elements - white blood cells, red blood cells, and platelets -have been reported.

Postmarketing Experience
The following adverse reactions have been identified during postapproval use of INTRON A: nephrotic syndrome, renal failure, renal insufficiency, pancreatitis, psychosis including hallucinations, homicidal ideation, Stevens Johnson syndrome, toxic epidermal necrolysis, erythema multiforme, injection site necrosis, myositis, and hearing loss. A wide variety of autoimmune and immune-mediated disorders have been reported with alpha interferons, including idiopathic thrombocytopenic purpura and thrombotic thrombocytopenic purpura. Additionally, the following adverse reactions have been identified during postapproval use of INTRON A alone or in combination with REBETOL: aplastic anemia, pure red cell aplasia, asthenic conditions (including asthenia, malaise, fatigue), systemic lupus erythematosus, Vogt-Koyanagi-Harada syndrome, serous retinal detachment, pulmonary hypertension, peripheral neuropathy, cases of acute hypersensitivity reactions, including anaphylaxis, urticaria, and angioedema. Sarcoidosis or exacerbation of sarcoidosis has been reported. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

OVERDOSAGE
There is limited experience with overdosage. Postmarketing surveillance includes reports of patients receiving a single dose as great as 10 times the recommended dose. In general, the primary effects of an overdose are consistent with the effects seen with therapeutic doses of interferon alfa-2b. Hepatic enzyme abnormalities, renal failure, hemorrhage, and myocardial infarction have been reported with single administration overdoses and/or with longer durations of treatment than prescribed (see ADVERSE REACTIONS). Toxic effects after ingestion of interferon alfa-2b are not expected because interferons are poorly absorbed orally. Consultation with a poison center is recommended.

Treatment
There is no specific antidote for interferon alfa-2b. Hemodialysis and peritoneal dialysis are not considered effective for treatment of overdose.

DOSAGE AND ADMINISTRATION

General
IMPORTANT: INTRON® A is supplied as 1) Powder for Injection/Reconstitution; 2) Solution for Injection in Vials; 3) Solution for Injection in Multidose Pens. Not all dosage forms and strengths are appropriate for some indications. It is important that you carefully read the instructions below for the indication you are treating to ensure you are using an appropriate dosage form and strength.

To enhance the tolerability of INTRON A, injections should be administered in the evening when possible.

To reduce the incidence of certain adverse reactions, acetaminophen may be administered at the time of injection.

Hairy Cell Leukemia
(see DOSAGE AND ADMINISTRATION, General section)

Dose
The recommended dose for the treatment of hairy cell leukemia is 2 million IU/m2 administered intramuscularly or subcutaneously 3 times a week for up to 6 months. Patients with platelet counts of less than 50,000/mm3 should not be administered INTRON A intramuscularly, but instead by subcutaneous administration. Patients who are responding to thera