Pharmacokinetics of PEGylated Recombinant Human Erythropoietin in Rats

Table 1

Pharmacokinetic (PK) parameters calculated from plasma concentrations of TCA-precipitable radioactivity in rats after intravenous administration of ¹²⁵I-PEG-rHuEPO at the dose, of 1, 2, and 3 𝜇g/kg^a.

PK parameters	Mean ± SD (𝑛=5)
	1 𝜇g/kg	2 𝜇g/kg	3 𝜇g/kg
𝐴 (ng/mL)	5.3159±0.3669^b	8.1045±2.0216^c	6.8179±0.8774^bc
𝛼 (1/h)	0.3940±0.1234	0.6870±0.3366	0.3957±0.2823
𝐵 (ng/mL)	6.0875±1.0421^b	9.9443±3.0194^c	21.6185±1.1005^d
𝛽 (1/h)	0.0313±0.0034	0.0273±0.0054	0.0334±0.0033
𝑉𝑐 (mL/kg)	17.7407±2.1606	23.3783±5.5114	21.1202±0.7322
𝑡1/2𝛼 (h)	1.9009±0.5890	1.1983±0.4871	2.5003±1.4982
𝑡1/2𝛽 (h)	22.3658±2.5324	26.2094±4.8848	20.9201±1.9529
K21 (1/h)	0.2269±0.0783	0.3914±0.1934	0.3137±0.2241
K10 (1/h)	0.0547±0.0040^b	0.0479±0.0092^bc	0.0421±0.0040^c
K12 (1/h)	0.1437±0.0447^bc	0.2749±0.1398^b	0.0733±0.0589^c
AUC ((ng/mL)·h)	207.8230±9.5021^b	373.6992±47.8833^c	679.9779±70.8449^d
CLs (mL/kg/h)	0.9640±0.0450^bc	1.0826±0.1194^b	0.8904±0.0963^c

aAll values are reported as mean ± SD (𝑛=5).
^{b, c, d}Means in the same line with different letters of superscript are significantly different (𝑃<0.05).
Abbreviations: 𝐴 and 𝐵, hybrid coefficients; 𝛼 and 𝛽, hybrid first-order rate constants; 𝑡1/2𝛼 and 𝑡1/2𝛽, initial and terminal phase half-lives; 𝑉_𝑐, volume of the central compartment; K21, elimination rate constant from the central compartment; K10, transport rate constant from circumjacent compartment to central compartment; K12, transport rate constant from circumjacent compartment to central compartment; AUC, area under plasma concentration time curve; CL_s, systemic clearance.