Deferasirox interacts with several common medication classes through metabolic (UGT, CYP) and chelation mechanisms. Understanding these interactions is essential for safe long-term therapy in patients who often have comorbidities and complex drug regimens.
Aluminium-Containing Antacids #
Avoid simultaneous administration. Deferasirox can chelate aluminium - clinical relevance is unclear but combined administration is not recommended. Stagger administration by at least 2 hours.
Effect of Other Drugs on Deferasirox #
| Concomitant Drug Class | Mechanism | Effect / Action |
|---|---|---|
| UGT inducers (rifampicin, phenytoin, phenobarbital, ritonavir) | Increased glucuronidation | Decreased deferasirox exposure - monitor ferritin; consider dose increase |
| UGT inhibitors / cholestyramine | Reduced enterohepatic recirculation | Decreased deferasirox exposure - avoid where possible |
| Strong CYP3A4 inducers | Minor secondary effect on deferasirox | Effect generally modest; monitor |
| Bile-acid sequestrants | Reduced biliary recirculation | May reduce efficacy |
Effect of Deferasirox on Other Drugs #
| Affected Drug Class | Mechanism | Effect / Action |
|---|---|---|
| CYP3A4 substrates (ciclosporin, simvastatin, hormonal contraceptives) | Deferasirox induces CYP3A4 | Reduced exposure of substrate - monitor clinically; consider non-hormonal contraception |
| CYP2C8 substrates (repaglinide, paclitaxel) | Deferasirox inhibits CYP2C8 | Increased substrate exposure - clinical caution |
| CYP1A2 substrates (theophylline) | Deferasirox inhibits CYP1A2 | Therapeutic drug monitoring advised for narrow-therapeutic-index drugs |
| Midazolam (CYP3A4 substrate) | CYP3A4 induction | Reduced midazolam exposure |
Drugs to Avoid or Use with Caution #
- Other iron chelators (deferoxamine, deferiprone): combination only under specialist supervision; increased toxicity risk
- Nephrotoxins (aminoglycosides, ciclosporin at high doses, NSAIDs): increased renal-failure risk
- NSAIDs / corticosteroids / oral bisphosphonates / anticoagulants: increased GI hemorrhage / ulceration risk
- Vitamin C in high doses: enhances iron mobilisation - clinically managed dose recommended
Practical Counselling #
A complete medication review is essential before initiating DEFRATAJ. Patients should be advised to inform their physician and pharmacist of any new prescription, over-the-counter or herbal product before adding it to their regimen. Periodic medication review during long-term therapy is recommended.