Table 2 In vitro PK parameters
From: An integrated pharmacokinetics ontology and corpus for text mining
Experiment types | Parameters | Description | Unit | References |
|---|---|---|---|---|
Single Drug Metabolism Experiment | Km | Michaelis-Menten constant. | mg L-1 | Segel p28. |
| Â | Vmax | Maximum velocity of the enzyme activity. | mg h-1 mg-1 protein | Segel p19 |
| Â | CLint | Intrinsic metabolic clearance is defined as ratio of maximum metabolism rate, Vmax, and the Michaelis-Menten constant, Km. | ml h-1 mg-1 protein | RT p165 |
| Â | Metabolic ratio | Parent drug/metabolite concentration ratio | NA | Â |
| Â | fmenzyme | Fraction of drug systemically available that is converted to a metabolite through a specific enzyme. | NA | RT xiii |
Single Drug Transporter Experiment | Papp | The apparent permeability of compounds across the monolayer cells. | cm/sec | Transport Consortium |
| Â | Re | Re is the ratio of basolateral to apical over apical to basolateral. | NA | Transport Consortium |
| Â | Radioactivity | Total radioactivity in plasma and bile samples is measured in a liquid scintillation counter | dpm/mg protein | Transport Consortium |
| Â | Uptake Volume | The amount of radioactivity associated with the cells divided by its concentration in the incubation medium. | ul/mg protein | Transport Consortium |
Drug Interaction Experiment | IC50 | Inhibitor concentration that inhibits to 50% of enzyme activity. | mg L-1 | Â |
| Â | Ki | Inhibition rate constant for competitive inhibition, noncompetitive inhibition, and uncompetitive inhibition. | mg L-1 | Segel p103 |
| Â | Kdeg | The natural degradation rate constant for the Enzyme. | h-1 | Rostami-Hodjegan and Tucker |
| Â | KI | The concentration of inhibitor associated with half maximal Inactivation in the mechanism based inhibition. | mg L-1 | Rostami-Hodjegan and Tucker |
| Â | Kinact | The maximum degradation rate constant in the presence of a high concentration of inhibitor in the mechanism based inhibition. | h-1 | Rostami-Hodjegan and Tucker |
| Â | Emax | Maximum induction rate | Unit free | Rostami-Hodjegan and Tucker |
| Â | EC50 | The concentration of inducer that is associated with the half maximal induction. | mg L-1 | Rostami-Hodjegan and Tucker |
Type of Drug Interactions | Competitive inhibition, noncompetitive inhibition, uncompetitive inhibition, mechanism based inhibition, and induction. | Rostami-Hodjegan and Tucker | Â | Â |