Table 1.

Physicochemical properties and in vivo doses for selected bases and quaternary amines.

Drug	Ion class	Solubilitya, µM	LogD7.4 b	pKa c	i.v./i.t. doses in the rat, µg/kg	i.v./i.t. doses in the dog, µg/kg
Salmeterol	Base	>380	2.2	9.1	14/18	–
Formoterol	Base	600	0.49	8.4	15/14	10/5
Salbutamol	Base	>2,900	−1.9	9.2	1,064/15	–
Terbutaline	Base	6,830	−1.5	9.3	1,038/1080	500/50
Indacaterol	Base	25	2.8	8.3	1,000/15	–
Tiotropium	QA	>2,800	<‐1.3	NA	10,000/53	80/0.7
Ipratropium	QA	>9,140	−1.0	NA	1,000/1,002	–
Glycopyrronium	QA	>4,050	0.12d	NA	282/8.1	–
AZD2115	Dibase	650	2.1	8.7/7.6	769/6.6	–
Batefenterol	Dibase	28	3.1	10/7.3	597/1.2	–
AZD4818	Dibase	>2,500	0.90	8.4/6.2	258/10.8	–
AZD3199	Dibase	2,510	2.3	9.5/7.1	1,000/15.7	–

LogD, logarithm of the distribution coefficient; NA, not applicable; QA, quaternary amine.

^aSolubility in phosphate buffer at pH 7.4, for method see ref. 12.

^bOctanol/water partition coefficient when aqueous phase is at pH7.4, for method see ref. 13.

^cFor method, see ref. 14.

ClogP.