Table 3.
Parameter estimates of the base model, the covariate model and the 1000 bootstrap runs (median and 95th percentiles)
| Parameter | Base model | Covariate (final) model | 1000 bootstrap replicates median (95% CI) |
|---|---|---|---|
| Objective Function Value | 3296 | 3039 | 3015 |
| Fixed parameters | |||
| CL/Fm (l h−1)* | 1.587 | 0.595 | 0.594 (0.548, 0.646) |
| V/Fm (l)† | 32.6 | 38.1 | 38.3 (33.2, 44.4) |
| Kfm | 0.19 | 0.447 | 0.438 (0.301, 0.628) |
| Random parameters (CV%) | |||
| BSV CL/Fm | 65 | 28 | 28 (21, 33) |
| BSV V/Fm | 66 | 45 | 44 (33, 54) |
| COV (CL/V), R | −0.13 | 0.33 | 0.30 (−0.12, 0.48) |
| BOV CL/Fm | 26 | 21 | 20 (13, 28) |
| Effects of covariates on CL/Fm | |||
| Creatinine clearance (θ6) | 0.0250 | 0.025 (0.021, 0.028) | |
| Diuretics (θ7) | −0.294 | −0.298 (−0.386, −0.207) | |
| Probenecid (θ8) | 0.383 | 0.384 (0.264, 0.499) | |
| Residual Error | |||
| Additive (mg l−1) | 0.63 | 1.32 | 1.32 (0.77, 1.64) |
| Proportional (CV%) | 22.0 | 13.1 | 12.9 (9.4, 17.2) |
CL/Fm, apparent clearance of oxypurinol; V/Fm, apparent volume of distribution; Kfm, formation rate constant; Diuretics, the effect of diuretic use (thiazide, furosemide, spironolactone) on oxypurinol clearance; Probenecid, the effect of probenecid on oxypurinol clearance; BSV, between subject variability; COV, covariance; r, correlation coefficient; BOV, between occasion variability; *For a typical patient that has a estimated creatinine clearance of 37.6 ml min−1; †For a typical patient who has a lean body weight of 60 kg.