TABLE 3.

Properties of representative inhaled, lung targeted compounds

Lung retention mechanism(s) for each compound are denoted by checkmarks.

Compound	Target	cLogP	cpKa	Lung Retention Mechanism(s)
				Dissolution-Limited	Tissue Affinity		Low Permeability	Slow Off-Rate
					Basic	Lipophilic
Fluticasone propionatea	Glucocorticoid receptor	3.3	<3	✓		✓
Fluticasone furoateb	Glucocorticoid receptor	3.7	<3	✓		✓
Salmeterol Xinafoatec	β2-adrenergic receptor	4.1	9.4	✓	✓	✓		✓d
Salbutamole	β2-adrenergic receptor	0.6	9.4		✓
Tiotropium bromidef	Muscarinic receptors (M3, M1)	−2.3	<3				✓	✓
Compound 3.05g	Epithelial sodium channel	−2.0	8.5		✓		✓
GSK2269557/Nemiralisibh	PI3Kδ	4.8	8.7, 4.1		✓	✓

^aCrim et al. (2001).

^bDaley-Yates (2015).

^cAnderson et al. (1994).

^dApparent slow off-rate likely due to partitioning into lipid membrane bilayers.

^eAnderson et al. (1994), Dickson et al. (2016), and references therein.

^fMundy and Kirkpatrick (2004), Eriksson et al. (2018).

^gKley et al. (2016).

^hDown et al. (2015).