CLINICAL PHARMACOLOGY
Mechanism of Action
The mechanism by which PLEGRIDY exerts its effects in patients with multiple sclerosis is unknown.
Pharmacodynamics
There is no biochemical or physiologic effect known to relate directly to the clinical effect of PLEGRIDY.
Pharmacokinetics
After single-dose or multiple-dose subcutaneous administration of PLEGRIDY to healthy subjects, serum PLEGRIDY peak concentration (Cmax) and total exposure over time (area under the curve, or AUC) increased in proportion to doses from 63 to 188 micrograms. PLEGRIDY did not accumulate in the serum after multiple doses of 125 micrograms every 14 days. Pharmacokinetic parameters for PLEGRIDY, including Cmax and AUC, did not differ significantly between healthy volunteers and multiple sclerosis patients or between single-dose and multiple-dose administrations. However, the coefficient of variation between individual patients for AUC, Cmax, and half-life was high (41% to 68%, 74% to 89%, and 45% to 93%, respectively).
Absorption
After 125 microgram subcutaneous doses of PLEGRIDY in multiple sclerosis patients, the maximum concentration occurred between 1 and 1.5 days, the mean Cmax was 280 pg/mL, and the AUC over the 14 day dosing interval was 34.8 ng.hr/mL.
Distribution
In multiple sclerosis patients taking 125 microgram subcutaneous doses of PLEGRIDY every 14 days, the estimated volume of distribution was 481 liters.
Metabolism and Elimination
Clearance mechanisms for PLEGRIDY include catabolism and excretion. The major pathway of elimination is renal. The half-life is approximately 78 hours in multiple sclerosis patients. The mean steady state clearance of PLEGRIDY is approximately 4.1 L/hr. PLEGRIDY is not extensively metabolized in the liver.
Specific Populations
Body weight, gender, and age do not require dosage adjustment.
Renal impairment can increase the Cmax and AUC for PLEGRIDY. Results of a pharmacokinetic study in patients with mild, moderate, and severe renal impairment (creatinine clearance 50 to 80, 30 to 50, and less than 30 mL/minute, respectively) showed increases above normal for Cmax of 27%, 26%, and 42%, and for AUC, increases of 30%, 40%, and 53%. The half-life was 53, 49, and 82 hours in patients with mild, moderate, and severe renal impairment, respectively, compared to 54 hours in normal subjects.
In the same study, subjects with end stage renal disease requiring hemodialysis two or three times weekly had AUC and Cmax of PLEGRIDY values that were similar to those of normal controls. Each hemodialysis session removed approximately 24% of circulating PLEGRIDY from the systemic circulation [see Use in Specific Populations (8.6)].
NONCLINICAL TOXICOLOGY
Carcinogenesis, Mutagenesis, Impairment of Fertility
Carcinogenesis
The carcinogenic potential of PLEGRIDY has not been tested in animals.
Mutagenesis
PLEGRIDY was not mutagenic when tested in an in vitro bacterial reverse mutation (Ames) test and was not clastogenic in an in vitro assay in human lymphocytes.
Impairment of Fertility
In monkeys administered interferon beta by subcutaneous injection over the course of one menstrual cycle, menstrual irregularities, anovulation, and decreased serum progesterone levels were observed. These effects were reversible after discontinuation of drug.
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