. Author manuscript; available in PMC: 2015 Aug 1.

Published in final edited form as: Biol Blood Marrow Transplant. 2014 Apr 13;20(8):1121–1129. doi: 10.1016/j.bbmt.2014.03.032

Table 3.

Population pharmacodynamics parameters describing relationship between total or unbound MPA concentrations and IMPDH activity on day +21 in nonmyeloablative HCT recipients taking MMF

Parameter	Explanation	Estimates^a [RSE%]^b for
		IMPDH activity (pmol XMP/10⁶ cells/h)

E₀	Baseline IMPDH activity (immediately before day +21 MMF dose)	1370 [5.6]

		Total MPA (mg/L)	Unbound MPA (ng/mL)

IC₅₀	MPA concentration causing 50% maximal inhibition	3.23 [10.7]	57.3[11.2]
IIV_E₀ (CV%)	Interindividual variability of E₀	27.6 [30.8]	27.3 [31.4]
IIV_IC₅₀	(CV%) Interindividual variability of IC₅₀	53.1 [34.2]	56.3 [33.4]
Proportional residual error (%)		0.20 [19.3]	0.20 [19.3]

Maximum inhibition (I_max) could not be estimated based on observed data and, therefore, was fixed to 1. Hill coefficient was estimated close to 1 and was fixed to 1 in the final parameter estimation.

The base model is the final model, because none of the evaluated covariates met the criteria for inclusion in the pharmacodynamic model.

Abbreviations: CV = coefficient of variation; IIV = interindividual variability; RSE = relative standard error.