Potency and selectivity of GSK256066, AWD 12-281, and roflumilast for PDEs
PDE activity was measured at room temperature using SPA assays and additionally, for PDE4B and PDE4D only fluorescence polarization assays. The binding of GSK256066 to the HARBS in rat brain cytosol was measured using a competition binding assay with 2 nM [methyl-3H]rolipram as radioligand. Where n = 1 the values are means of duplicate determinations in a single experiment, except for HARBS data for GSK256066 (mean of three determinations in a single study) and cilomilast, which was a single determination only, for the latter the data are consistent with the 100 nM Ki published previously (Barnette et al., 1994).
| GSK256066 | AWD 12–281 | Roflumilast | Cilomilast | ||
|---|---|---|---|---|---|
| pIC50 (mean ± S.E.M. or range) | Selectivity vs. PDE4B | pIC50 | pIC50 (mean ± S.E.M.) | pIC50 (mean ± S.E.M.) | |
| PDE4Ba | ≥11.5 (n = 12) | 1.0 | 7.63 ± 0.23 (n = 2) | 9.41 ± 0.04 (n = 129) | 7.13 ± 0.08 (n = 4) |
| PDE4Aa | ≥11.31 (n = 4) | 1.6 | ND | 9.36 ± 0.08 (n = 56) | N.D. |
| PDE4Ca | ≥11.42 (n = 4) | 1.2 | ND | 8.78 ± 0.06 (n = 30) | N.D. |
| PDE4Da | ≥11.94 (n = 12) | 0.4 | 7.52 ± 0.64 (n = 2) | 9.52 ± 0.05 (n = 112) | N.D. |
| PDE1 | 5.73 ± 0.03 (n = 2) | ≥600,000 | <4.52 (n = 1) | <4.52 (n = 1) | N.D. |
| PDE2 | 5.92 ± 0.05 (n = 2) | ≥390,000 | <4.52 (n = 1) | <4.52 (n = 1) | N.D. |
| PDE3 | 5.93 ± 0.12 (n = 5) | ≥380,000 | <4.52 (n = 1) | <5 (n = 3) | <4.5 (n = 1) |
| PDE5 | 5.49 ± 0.04 (n = 5) | ≥1,050,000 | <4.65 (n = 3) | <4.55 (n = 3) | <4.5 (n = 1) |
| PDE6 | 5.28 ± 0.03 (n = 5) | ≥1,700,000 | <4.52 (n = 1) | <5 (n = 2) | N.D. |
| PDE7 | 8.11 ± 0.26 (n = 2) | ≥2510 | <4.52 (n = 1) | <6.6 (n = 2) | N.D. |
| HARBS | 10.27 (n = 1) | ≥17 | 7.40 ± 0.37 (n = 3) | 8.98 ± 0.08 (n = 11) | 6.75 (n = 1) |
N.D., not determined
↵a PDE4 potency is likely to be an underestimate because the derived IC50 value is similar to the estimated in-assay enzyme concentrations.