ects.
Patients with higher serum ferritin may require up to 55 mg/kg/day. It is inadvisable to regularly exceed an average daily dose of 50 mg/kg/day except when very intensive chelation is needed in patients who have completed growth. If ferritin values fall below 1000 ng/mL, the risk of Desferal toxicity increases; it is important to monitor these patients particularly carefully and perhaps to consider lowering the total weekly dose.
To assess the chelation therapy, 24 hour urinary iron excretion should initially be monitored daily. Starting with a dose of 500 mg daily the dose should be raised until a plateau of iron excretion is reached. Once the appropriate dose has been established, urinary iron excretion rates can be assessed at intervals of a few weeks.
Alternatively the mean daily dose may be adjusted based on ferritin level in order to keep the therapeutic index below 0.025 (i.e. the mean daily dose (mg/kg) of Desferal divided by the serum ferritin level (micro g/L) should be below 0.025). ). The therapeutic index is a valuable tool in protecting the patient from excess chelation, but it is not a substitute for careful clinical monitoring.
Mode of administration:
Slow subcutaneous infusion using a portable, light-weight, infusion pump over a period of 8-12 hours is effective and particularly convenient for ambulant patients. It may be possible to achieve a further increase in iron excretion by infusing the same daily dose over a 24 hour period. Desferal should normally be used with the pump 5-7 times a week. Desferal is not formulated to support subcutaneous bolus injection.
Since the subcutaneous infusions are more effective, intramuscular injections are given only when subcutaneous infusions are not feasible.
Elderly
Clinical studies of Desferal did not include sufficient numbers of subjects aged 65 years and over to determine whether they respond differently compared to younger subjects. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy' (see sections 4.4 Special warnings and precautions for use and 4.8 Undesirable effects).
Hepatic impairment
No studies have been performed in patients with hepatic impairment.
Intravenous infusion during blood transfusion
The availability of an intravenous line during blood transfusions makes it possible to administer an intravenous infusion, e.g. in patients who comply poorly with and/or do not tolerate subcutaneous infusions.
The Desferal solution should not be put directly into the blood bag but may be added to the blood line by means of a “Y” adaptor located near to venous site of injection. The patient's pump should be used to administer Desferal as usual. Because of the limited amount of drug that can be administered by IV infusion during blood transfusion, the clinical benefit of this mode of administration is limited. Patients and nurses should be warned against accelerating the infusion, as an intravenous bolus of Desferal may lead to flushing, hypotension and circulatory collapse (see section 4.4 Special warnings and precautions for use).
Continuous intravenous infusion is recommended for patients incapable of continuing subcutaneous infusions and in those who have cardiac problems secondary to iron overload. 24 hour urinary iron excretion should be measured |
