TABLE 3

Final population PD 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.
			%		%
BSL, ng/ml	Baseline neopterin serum concentration	2.97	6	Same as IFN β-1a	Same as IFN β-1a
Loss, h⁻¹	First-order elimination rate of serum neopterin	0.0174	7	Same as IFN β-1a	Same as IFN β-1a
E_max	Maximum stimulatory effect	198	31	Same as IFN β-1a	Same as IFN β-1a
MTT, h	Mean transit time in transit compartments	7.13	6	5.60	4
EC₅₀, pg/ml	Drug concentration to achieve 50% of E_max	2980	44	62,200	26
IC₅₀, ng/ml	Neopterin concentration to inhibit 50% of the stimulatory effect	1.82	29	Same as IFN β-1a	Same as IFN β-1a
ω²_BSL	Intersubject variance of V_C	0.264	27	Same as IFN β-1a	Same as IFN β-1a
ω²_Emax	Intersubject variance of Q	0.185	31	Same as IFN β-1a	Same as IFN β-1a
Cov_{BSL_Emax}	Covariance of BSL and E_max	−0.0859	38	Same as IFN β-1a	Same as IFN β-1a
S.D.	Coefficient of residual error	0.173	8	Same as IFN β-1a	Same as IFN β-1a
σ²	Residual error variance	1, Fixed	N.A.	1, Fixed	N.A.