The pharmacokinetics of etanercept in healthy volunteers.
OBJECTIVE
To describe the pharmacokinetics of etanercept when administered by subcutaneous injection in single doses to healthy volunteers.


METHODS
Twenty-six healthy volunteers between 19 and 50 years of age received single doses of etanercept 25 mg by subcutaneous injection into the abdomen. Serial serum samples were collected for 21 days. An enzyme-linked immunosorbent assay with a quantitation limit of 0.3 ng/mL was used to measure the drug concentrations.


RESULTS
Etanercept was well tolerated by healthy volunteers. A one-compartment model was found to best describe the concentration-time data and was used to determine the pharmacokinetic parameters. Etanercept is slowly absorbed from the site of injection with a time of peak concentration (+/- SD) of 51 +/- 14 hours; peak concentration was 1.46 +/- 0.72 mg/L. The AUC was 235 +/-98 mg x h/L, apparent clearance was 132 +/- 85 mL/h, apparent volume of distribution was 12 +/- 6 L, and the half-life was 68 +/- 19 hours.


CONCLUSIONS
Etanercept was slowly absorbed and slowly eliminated after subcutaneous administration. Dosing at the recommended rate of 25 mg twice weekly would be expected to result in concentrations of approximately 3 mg/L. Intersubject variability for apparent clearance in healthy volunteers was 64%.
Korth-Bradley
J M
JM
Clinical Pharmacokinetics, Wyeth-Ayerst Research, Philadelphia, PA 19101, USA. korthbj@war.wyeth.com
Rubin
A S
AS
Hanna
R K
RK
Simcoe
D K
DK
Lebsack
M E
ME
D000293:Adolescent; D000328:Adult; D018501:Antirheumatic Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001682:Biological Availability; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006207:Half-Life; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics
D018501:Antirheumatic Agents; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins