ts on Day 8 and 9 of gestation resulted in dose dependent embryotoxicity and gross abnormalities. There are no adequate and well-controlled studies in pregnant women. Elspar should be given to a pregnant woman only if clearly needed.
8.3 Nursing Mothers
It is not known whether Elspar 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 ELSPAR, a decision should be made to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
8.4 Pediatric Use
[See Clinical Studies (14)]
8.5 Geriatric Use
Clinical studies of Elspar did not include sufficient numbers of subjects aged 65 and older to determine whether they respond differently from younger subjects.
11 DESCRIPTION
Elspar (asparaginase) contains the enzyme L-asparagine amidohydrolase, type EC-2, derived from Escherichia coli. Elspar activity is expressed in terms of International Units according to the recommendation of the International Union of Biochemistry. One International Unit of asparaginase is defined as that amount of enzyme required to generate 1 μmol of ammonia per minute at pH 7.3 and 37°C. The specific activity of Elspar is at least 225 International Units per milligram of protein.
Elspar is provided as a sterile, white lyophilized plug or powder. Each vial contains 10,000 International Units of asparaginase and 80 mg of mannitol.
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action
The mechanism of action of Elspar is thought to be based on selective killing of leukemic cells due to depletion of plasma asparagine. Some leukemic cells are unable to synthesize asparagine due to a lack of asparagine synthetase and are dependent on an exogenous source of asparagine for survival. Depletion of asparagine, which results from treatment with the enzyme L-asparaginase, kills the leukemic cells. Normal cells, however, are less affected by the depletion due to their ability to synthesize asparagine.
12.2 Pharmacodynamics
The relationship between asparaginase activity and asparagine levels has been studied in clinical trials. In previously untreated, standard-risk ALL patients treated with native asparaginase in whom plasma enzyme activity was greater than 0.1 International Units/mL, plasma asparagine levels decreased from a pretreatment average level of 41 μM to less than 3 μM. In this study, cerebrospinal fluid asparagine levels in patients treated with asparaginase decreased from 2.8 μM (pretreatment) to 1.0 μM and 0.3 μM at day 7 and day 28 of induction, respectively.
12.3 Pharmacokinetics
In a study in patients with metastatic cancer and leukemia, daily intravenous administration of L-asparaginase resulted in a cumulative increase in plasma levels. Plasma half-life varied from 8 to 30 hours. Apparent volume of distribution was slightly greater than the plasma volume. Asparaginase levels in cerebrospinal fluid were less than 1% of concurrent plasma levels.
In a study in which patients with leukemia and metastatic cancer received intramuscular L-asparaginase, peak plasma levels of asparaginase were reached 14 to 24 hours after dosing. Plasma half-life was 34 to 49 hours.
13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
No long-term carcinogenicity studies in animals |
