TABLE 2

Population PK model parameters (fixed and random effects), including percentage of relative S.E.

Model Parameter	Definition	IFN β-1a		PEG-IFN β-1a
Model Parameter	Definition	Estimated Value	Relative S.E.	Estimated Value	Relative S.E.
			%		%
Ka_SC, h⁻¹	Absorption rate after subcutaneous administration	1.37	55	0.0892	2
Ka_IM, h⁻¹	Absorption rate after intramuscular administration	1.65	42	0.461	17
V_C, ml/kg	Central compartment volume of distribution	1610	18	107	0.1
V_P, ml/kg	Peripheral compartment volume of distribution	1170	28	105	0.1
CL, ml/kg/h	Clearance	314	8	8.53	0.1
Q, ml/kg/h	Intercompartmental clearance between central and peripheral compartment	67.6	40	52.5	0.5
F _SC	Relative bioavailability to intramuscular	0.781	11	0.868	0.02
F_IM	Relative bioavailability	1, Fixed	N.A.	1, Fixed	N.A.
ω²_Vc	Intersubject variance of V_C	0.127	71	0, Fixed	N.A.
ω²_CL	Intersubject variance of CL	0, Fixed	N.A.	0.0233	21
ω²_Q	Intersubject variance of Q	0.487	117	4.6	0.5
cov_{Vc_Q}	Covariance of V_C and Q	0.106	69	0, Fixed	N.A.
cov_{CL_Q}	Covariance of CL and Q	0, Fixed	N.A.	−0.0353	10
SD	Coefficient of residual error	0.397	10	0.399	0.1
σ²	Residual error variance	1, Fixed	N.A.	1, Fixed	N.A.