IUP ED50 (1) | MAP ED50 (2) | Hypotensive ED10 mm Hg (3) | Selectivity Ratio | ||
---|---|---|---|---|---|
(2)/(1) | (3)/(1) | ||||
Fiduxosin | 0.24 (0.08) | 1.79 (0.47) | >3.0 | 7.5 | >12.5 |
Tamsulosin | 0.004 (0.003) | 0.006 (0.005) | 0.03 (0.13) | 1.5 | 7.5 |
Terazosin | 0.23 (0.09) | 0.09 (0.06) | 0.16 (0.11) | 0.4 | 0.7 |
The effective doses of each antagonist required to produce the following effects were calculated: maximum 50% inhibition of IUP pressor effect (1), maximum 50% inhibition of MAP pressor effect and (2), 10 mm Hg decrease in baseline MAP (3). Uroselectivity ratios are summarized in the last two columns. Using the first two indices, the IUP selectivity of fiduxosin (7.5-fold) was superior to that of tamsulosin (1.5-fold) or terazosin (ratio = 0.4- or 2.5-fold MAP-selective). IUP selectivity as defined by IUP versus hypotensive effects yields the same rank order: fiduxosin (>12.5-fold) > tamsulosin (7.5-fold) > terazosin (0.7-fold). The actual uroselectivity of fiduxosin may be underestimated as the absence of hypotension after fiduxosin precludes an absolute estimate.