Pharmacokinetics model representation of denosumab: compartment I represents the subcutaneous tissue with denosumab being present at mass concentration mden,sub, whereas compartment II represents the blood serum with denosumb being present at mass concentration mden,ser; the compartment concentrations are governed by absorption rate kabs, degradation rates korg and kenz, and the administered dose Dden (which is related to Δmden,sub).