Table 2. Pharmacokinetic parameters (mean ± standard deviation [SD]) following the oral administration of sildenafil at 1, 2 and 4 mg/kg in dogs with chronic embolic pulmonary hypertension (each n=4).
| Pharmacokinetic Parameter |
1 mg/kg | 2 mg/kg | 4 mg/kg |
|---|---|---|---|
| Mean ± SD | Mean ± SD | Mean ± SD | |
| Cmax (ng/ml) | 154.5 ± 41.9 | 352.5 ± 192.3 | 500.7 ± 216.6 |
| Tmax (hr) | 1.0 ± 0.7 | 1.1 ± 0.2 | 1.5 ± 0.4 |
| AUCinf (ng·hr/ml) | 659.7 ± 282.5 | 1,313 ± 517.9 | 2,512.4 ± 1,185.9 |
| AUC extrap (%) | 8.0 ± 4.4 | 6.8 ± 1.3 | 10.3 ± 1.6 |
| AUMCinf (ng·hr2/ml) | 2,805.5 ± 1,580.8 | 5,962.7 ± 2,273.2 | 13,734.5 ± 6,842.0 |
| MRT (hr) | 4.0 ± 0.7 | 4.6 ± 0.3 | 5.4 ± 0.3a) |
| t1/2 (hr) | 2.6 ± 0.5 | 3.0 ± 0.2 | 3.5 ± 0.3a) |
| CL/F (l/hr/kg) | 1.8 ± 0.8 | 1.7 ± 0.6 | 2.0 ± 1.1 |
| V/F (l/kg) | 6.2 ± 1.5 | 7.4 ± 2.8 | 10.1 ± 6.4 |
a) P<0.05 vs. 1 mg/kg. Cmax, maximum plasma concentration; Tmax, time to maximum plasma concentration; AUCinf, area under the curve from time 0 to infinity; AUC extrap, percent of the AUC extrapolated to infinity; AUMCinf, area under the moment curve extrapolated to infinity; MRT, mean residence time; t1/2, elimination half-life; CL/F, apparent plasma clearance per bioavailability; V/F, apparent volume of distribution per bioavailability.