inetic properties
Certolizumab pegol plasma concentrations were broadly dose-proportional. Pharmacokinetics observed in patients with rheumatoid arthritis were consistent with those seen in healthy subjects.
Absorption
Following subcutaneous administration, peak plasma concentrations of certolizumab pegol were attained between 54 and 171 hours post-injection. Certolizumab pegol has a bioavailability (F) of approximately 80% (range 76% to 88%) following subcutaneous administration compared to intravenous administration.
Distribution
The apparent volume of distribution (V/F) was estimated at 8.01 l in a population pharmacokinetic analysis of patients with rheumatoid arthritis.
Biotransformation and elimination
PEGylation, the covalent attachment of PEG polymers to peptides, delays the elimination of these entities from the circulation by a variety of mechanisms, including decreased renal clearance, decreased proteolysis, and decreased immunogenicity. Accordingly, certolizumab pegol is an antibody Fab' fragment conjugated with PEG in order to extend the terminal plasma elimination half-life of the Fab' to a value comparable with a whole antibody product. The terminal elimination phase half-life (t1/2) was approximately 14 days for all doses tested.
Clearance following subcutaneous dosing was estimated to be 21.0 ml/h in a rheumatoid arthritis population pharmacokinetic analysis, with an inter-subject variability of 30.8% (CV) and an inter-occasion variability of 22.0%. The presence of antibodies to certolizumab pegol resulted in an approximately three-fold increase in clearance. Compared with a 70 kg person, clearance is 29% lower and 38% higher, respectively, in individual RA patients weighing 40 kg and 120 kg.
The Fab' fragment comprises protein compounds and is expected to be degraded to peptides and amino acids by proteolysis. The de-conjugated PEG component is rapidly eliminated from plasma and is to an unknown extent excreted renally.
Special populations
Renal impairment
Specific clinical trials have not been performed to assess the effect of renal impairment on the pharmacokinetics of certolizumab pegol or its PEG fraction. However, population pharmacokinetic analysis based on subjects with mild renal impairment showed no effect of creatinine clearance. There are insufficient data to provide a dosing recommendation in moderate and severe renal impairment. The pharmacokinetics of the PEG fraction of certolizumab pegol are expected to be dependent on renal function but have not been assessed in patients with renal impairment.
Hepatic impairment
Specific clinical trials have not been performed to assess the effect of hepatic impairment on the pharmacokinetics of certolizumab pegol.
Elderly (65 years old)
Specific clinical trials have not been performed in elderly subjects. However, no effect of age was observed in a population pharmacokinetic analysis in patients with rheumatoid arthritis in which 78 subjects (13.2% of the population) were aged 65 or greater and the oldest subject was aged 83 years.
Gender
There was no effect of gender on the pharmacokinetics of certolizumab pegol. As clearance decreases with decreasing body weight, females may generally obtain somewhat higher systemic exposure of certolizumab pegol.
Pharmacokinetic/pharmacodynamic relationship
On the basis of Phase II and Phase III clinical trial data, a population exposure-response relatio |
