Table 1.
Parameter estimates used for the pharmacokinetics models of oxybutynin and risperidone (sum of active moieties, risperidone plus 9-hydroxyrisperidone)
| Drug/metabolite | Pharmacokinetic parameters |
|---|---|
| Risperidone | |
| Risperidone active moiety (2 mg oral) | V/F = 47.7 l; kel = 0.1 h−1; ka = 6.02 h−1 |
| Risperidone injectable (12.5 mg) | Non-compartmental analysis with linear interpolations between data points |
| Oxybutynin | |
| R-oxybutynin (10 mg) | V/F = 1.89 l; kel = 0.23 h−1; ka = 0.05 h−1 |
| R-oxybutynin (5 mg) | V/F = 1.17 l; ka = 0.99 h−1; α = 0.82 h−1; β = 0.044 h−1 |
| R-desethyloxybutynin (5 mg) | km = 1.40 h−1; α = 0.90 h−1; β = 0.20 h−1 |
| R-desethyloxybutynin (10 mg) | km = 0.07 h−1; kel = 0.21 h−1 |
V/F, apparent volume of distribution normalized by the bioavailable fraction; kel, elimination rate constant; ka, absorption rate constant; α and β are the rate constants for the two-compartment model; km, the rate constant for metabolite formation.