ng Mothers
It is not known whether Ontak is excreted in human milk. Because many drugs are excreted in human milk, and because of the potential for serious adverse reactions in nursing infants from Ontak, a decision should be made whether to discontinue nursing or to discontinue Ontak, taking into account the importance of the drug to the mother.
8.4 Pediatric Use
Safety and effectiveness in pediatric patients have not been established.
8.5 Geriatric Use
Clinical studies of Ontak did not include sufficient numbers of subjects aged 65 and older to determine whether they respond differently from younger subjects.
10 OVERDOSAGE
Doses of approximately twice the recommended dose (31 mcg/kg/day) resulted in moderate-to-severe nausea, vomiting, fever, chills and/or persistent asthenia.
11 DESCRIPTION
Ontak (denileukin diftitox), is a recombinant DNA-derived cytotoxic protein composed of the amino acid sequences for diphtheria toxin fragments A and B (Met-Thr)-His and the sequences for human interleukin-2 (IL-2; Ala-Thr). It is produced in an E. coli expression system and has a molecular weight of 58 kD. Neomycin is used in the fermentation process but is undetectable in the final product. Ontak is supplied in single use vials as a sterile, frozen solution intended for intravenous (IV) administration. Each 2 mL vial of Ontak contains 300 mcg of recombinant denileukin diftitox in a sterile solution of citric acid (20 mM), EDTA (0.05 mM) and polysorbate 20 (<1%) in Water for Injection, USP. The solution has a pH range of 6.9 to 7.2.
12 CLINICAL PHARMACOLOGY
12.1 Mechanism Of Action
Denileukin diftitox is a fusion protein designed to direct the cytocidal action of diphtheria toxin to cells which express the IL-2 receptor. Ex vivo studies report that after binding to the IL-2 receptor on the cell surface, denileukin diftitox is internalized by receptor-mediated endocytosis. The fusion protein is subsequently cleaved, releasing diphtheria toxin enzymatic and translocation domains from the IL-2 fragment, resulting in the inhibition of protein synthesis and ultimately, cell death.
12.3 Pharmacokinetics
Pharmacokinetic parameters associated with denileukin diftitox were determined over a range of doses (3 to 31 mcg/kg/day) in patients with lymphoma. Denileukin diftitox was administered as an IV infusion following the schedule used in the clinical trials. Following the first dose, denileukin diftitox displayed 2-compartment behavior with a distribution phase (half-life approximately 2 to 5 minutes) and a terminal phase (half-life approximately 70 to 80 minutes). Systemic exposure was variable but proportional to dose. Mean clearance was approximately 0.6 to 2.0 mL/min/kg and the mean volume of distribution was similar to that of circulating blood (0.06 to 0.09 L/kg). The mean clearance increased approximately 2- to 8-fold from course 1 to course 3 corresponding to a decrease in exposure of approximately 75%. No accumulation was evident between the first and fifth doses. Gender and age have no effect on pharmacokinetics of denileukin diftitox.
13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
There have been no studies to assess the carcinogenic potential of denileukin diftitox. Denileukin diftitox showed no evidence of mutagenicity in the Ames test and the chromosomal aberration assay. There have been no studie
