avenous administration of Desferal is the preferred route and the recommended rate for infusion is 15 mg/kg per hour and should be reduced as soon as the situation permits, usually after 4 to 6 hours so that the total intravenous dose does not exceed a recommended 80 mg/kg in any 24 hour period.
However, if the option to infuse intravenously is not available and if the intramuscular route is used the normal dosage is 2 g for an adult and 1g for a child, administered as a single intramuscular dose.
The decision to discontinue Desferal therapy must be a clinical decision; however, the following suggested criteria are believed to represent appropriate requirements for the cessation of Desferal. Chelation therapy should be continued until all of the following criteria are satisfied:
• the patient must be free of signs and symptoms of systemic iron poisoning (e.g. no acidosis, no worsening hepatoxicity),
• ideally, a corrected serum iron level should be normal or low (when iron level falls below 100 micro g/dL). Given that laboratories cannot measure serum iron concentrations accurately in the presence of Desferal, it is acceptable to discontinue Desferal when all other criteria are met if the measured serum iron concentration is not elevated.
• Repeat abdominal radiograph test should be obtained in patients who initially demonstrated multiple radio-opacities to ensure they have disappeared before Desferal is discontinued because they serve as a marker for continued iron absorption,
• If the patient initially developed vin-rose coloured urine with Desferal therapy, it seems reasonable that urine colour should return to normal before halting Desferal ( absence of vin-rose urine is not sufficient by itself to indicate discontinuation of Desferal).
The effectiveness of treatment is dependent on an adequate urine output in order that the iron complex (ferrioxamine) is excreted from the body. Therefore if oliguria or anuria develop, peritoneal dialysis or haemodialysis may become necessary to remove ferrioxamine.
It should be noted that the serum iron level may rise sharply when the iron is released from the tissues.
Theoretically 100 mg Desferal can chelate 8.5 mg of ferric iron.
Chronic Iron Overload
The main aim of therapy in well-controlled patients is to maintain an iron balance and prevent haemosiderosis, whilst in overloaded patients a negative iron balance is desirable in order to deplete the increased iron stores and to prevent the toxic effects of iron.
Adults and children:
Desferal therapy should be commenced after the first 10- 20 blood transfusions, or when there is evidence from clinical monitoring that chronic iron overload is present (e.g. serum ferritin >1000 ng/mL. The dose and mode of administration should be individually adapted according to the degree of iron overload.
Growth retardation may result from iron overload or excessive Desferal doses. If chelation is started before 3 years of age growth must be monitored carefully and the mean daily dose should not exceed 40mg/kg. (see section 4.4 Special warnings and precautions for use).
Dose:
The lowest effective dose should be used. The average daily dose will probably lie between 20 and 60 mg/kg/day. Patients with serum ferritin levels of < 2000 ng/mL should require about 25 mg/kg/day, and those with levels between 2000 and 3000 ng/mL about 35 mg/kg/day. Higher doses should only be employed if the benefit for the patient outweighs the risk of unwanted eff |
