. 2013 Jul 9;15(4):1012–1024. doi: 10.1208/s12248-013-9505-3

Table I.

Tissue-to-Plasma Partition Coefficients (K _p) of the Model Drugs

Tissue	Metformin^a	Digoxin^b		Midazolam^b		Emtricitabine^a
Tissue	Metformin^a	PP	Pregnancy	PP	Pregnancy	Emtricitabine^a
Lung	1.53	9.36	8.95	0.31	0.33	3.95
Adipose	0.25	1.02	0.98	1.88	2.35	0.95
Muscle	1.73	35.7	35.7	0.59	0.72	3.75
Liver	1.64	10.83	10.34	0.95	1.16	3.8
Spleen	1.67	7.88	7.56	0.62	0.75	3.9
Heart	1.45	5.75	5.53	0.73	0.87	3.95
Brain	1.69	1.92	1.94	1.44	1.78	4
Kidney	1.55	11.78	11.24	0.64	0.77	3.9
Skin	1.23	3.61	3.50	0.9	1.06	3.6
Reproductive organ (fetoplacental unit)	1.55	11.78	11.24	0.66	0.76	3.9
Red bone marrow	0.95	2.0	2.0	1.66	2.03	2.25
Yellow bone marrow	0.25	1.02	0.98	1.88	2.35	0.95
Rest of body	1.67	7.88	7.56	0.65	0.78	3.75

^aThe f _up of metformin and emtricitabine in plasma protein is assumed constant during pregnancy and PP since there are no data available to provide evidence that the f _up values change during pregnancy. Therefore, K _p values are not adjusted by f _up during pregnancy

^bThe f _up values of digoxin and midazolam in plasma during pregnancy and PP (19) are available and thereby K _p values are adjusted by f _up during pregnancy