Table 4.

Dissociation constants (K_i) for muscarinic receptor antagonists in human mucosal membranes

Drug	N	Hill slopea	Ki (nM)b	Ki site 1	Ki site 2	% Ha, c
AQ-RA 741	3	0.69±0.05	3.5 (2.8–4.3)	N/A
Methoctramine	5	0.71±0.07	38.8 (28.9–52.3)	N/A
Darifenacin	5	0.67±0.05	144 (113–184)	1.9 (0.4–10.0)	325 (206–511)	22±4
Pirenzepine	5	0.87±0.06	1600 (1320–1940)	N/A

K_i values were calculated according to the equation K_i=IC₅₀/(1+200/100.5).

^aData are expressed as mean±s.e.m.

^bData are derived from simultaneous analysis of all competition curves and are expressed as geometric mean K_i (95% confidence intervals).

^c% H, indicates % of high-affinity sites.