The pharmacodynamic effects of deferasirox flow directly from its high-affinity, selective binding of ferric iron (Fe3+): continuous depletion of the labile iron pool, mobilisation of tissue iron stores, and dose-dependent reductions in serum ferritin and liver iron concentration (LIC) over time.
Primary Pharmacodynamic Effect #
Deferasirox is a tridentate iron chelator: two molecules wrap around a single Fe3+ ion in a 2:1 ligand-to-metal ratio, forming a stable, neutral, hexacoordinate complex. The complex is redox-inactive, preventing iron-catalysed Fenton-type generation of hydroxyl radicals - a key driver of organ damage in chronic iron overload.
Iron Selectivity #
Deferasirox has a high affinity for Fe3+ and substantially lower affinity for biologically essential trace metals such as zinc and copper. This selectivity supports long-term safety by minimising depletion of essential mineral pools and preserving normal physiological function.
Iron Negative Balance #
At clinically used doses, deferasirox produces a net negative iron balance in patients receiving regular transfusions. The achieved iron excretion typically outpaces the iron load of standard transfusion regimens, allowing total body iron stores to fall over months of therapy.
Surrogate PD Markers #
| Marker | What It Reflects | Typical Monitoring Frequency |
|---|---|---|
| Serum ferritin | Body iron stores (with limitations - can be elevated by inflammation) | Monthly |
| Liver Iron Concentration (LIC) by MRI R2 or T2* | Hepatic iron burden - the largest iron storage compartment | Every 6-12 months |
| Cardiac T2* | Myocardial iron loading - risk of cardiomyopathy | Annually in selected patients |
| Labile plasma iron (LPI) | Direct measure of toxic, non-transferrin-bound iron | Research / specialised centres |
Time-Course of PD Effect #
Deferasirox produces a rapid suppression of labile plasma iron within hours of dosing. Reductions in serum ferritin become evident over weeks; meaningful decreases in LIC are typically seen over 6-12 months of consistent therapy. Cardiac iron mobilisation is slower and benefits accrue over multiple years of sustained chelation.
PD-Based Dose Adjustment #
Because PD response is dose-dependent, prescribing information typically supports dose escalation in 5-10 mg/kg/day increments every 3-6 months when serum ferritin remains persistently above target, balanced against tolerability and laboratory monitoring (renal/hepatic).
Clinical PD Outcomes #
Sustained deferasirox therapy is associated with reductions in ferritin and LIC, stabilisation or improvement in cardiac iron, and clinical outcomes including preserved cardiac and endocrine function. The full programme of clinical evidence is summarised on the Clinical Studies page.