Rapid intravenous infusion: Rapid intravenous infusion may lead to hypotension and shock (e.g. flushing, tachycardia, circulatory collapse and urticaria).
Visual and hearing impairment: High doses of Desferal, especially in patients with low ferritin plasma levels, may lead to disturbances of vision and hearing (see Adverse Reactions). Patients with renal failure who are on maintenance dialysis and have low ferritin levels may be particularly prone to adverse reactions, visual symptoms having been reported after single doses of Desferal. The risk of side effects is reduced when low-dose therapy is employed. If visual or auditory disturbances occur, Desferal should be discontinued immediately. The changes induced by Desferal are usually reversible if identified early. Treatment with Desferal may be resumed later at a reduced dose, with close monitoring of audiovisual function.
Specialist ophthalmological and audiological testing are recommended before the start of Desferal treatment, and at regular intervals thereafter (every 3 months), particularly if ferritin levels are low. The risk of audiometric abnormalities may be reduced in thalassemia patients if the ratio of the mean daily dose (mg/kg) of Desferal divided by the serum ferritin (micrograms/L) is kept below 0.025.
Renal impairment: Approximately half of the metal complex is excreted via the kidneys in iron-overloaded patients with normal renal function. Accordingly, caution is indicated in patients with severe renal failure. The iron and aluminum complexes of desferrioxamine are dialyzable; their elimination will be increased by dialysis in patients with renal failure.
Isolated cases of acute renal failure have been reported (see Adverse Reactions). Monitoring patients for changes in renal function (e.g. increased serum creatinine) should be considered.
Pediatrics: growth retardation: Patients with low serum ferritin levels on high doses of Desferal, or patients at young age (<3 years at commencement of treatment) have been associated with growth retardation (see Treatment for chronic iron overload under Dosage & Administration). Growth retardation if associated with excessive doses of Desferal must be distinguished from growth retardation resulting from iron overload. Growth retardation from Desferal use is rare if the dose is kept below 40 mg/kg. If growth retardation has been associated with doses above this value, then reduction of the dose may result in return in growth velocity, however, the predicted adult height will not be attained.
Pediatric patients receiving Desferal should be monitored for body weight and longitudinal growth every 3 months.
Acute respiratory distress syndrome: Acute respiratory distress syndrome has been described following treatment with excessively high i.v. doses of Desferal in patients with acute iron intoxication, and also in thalassaemic patients. The recommended daily doses should therefore not be exceeded.
Infections: In patients with iron overload it has been reported that Desferal increases susceptibility to infections, e.g. with Yersinia enterocolitica and Yersinia pseudotuberculosis. If a patient under treatment with Desferal develops fever accompanied by acute enteritis/enterocolitis, diffuse abdominal pain, or pharyngitis, treatment should be temporarily discontinued, bacteriological tests performed, and suitable antibiotic therapy started at once. Treatment with Desferal can be resumed after the infection has resolved.
Rare cases of mucormycosis, some with a fatal outcome, have been reported in patients receiving Desferal for aluminum and/or iron overload. If any of the suspected signs or symptoms occur, Desferal should be discontinued, mycological tests carried out and appropriate treatment instituted immediately. Mucormycosis may also occur in patients who are not receiving Desferal, indicating that other factors (such as dialysis, diabetes mellitus, disturbance of acid-base balance, hematological malignancies, immunosuppressive drugs, or a compromised immune system) may play a role in the development of this infection.
Cardiac impairment with high doses of vitamin C: In patients with severe chronic iron overload, impairment of cardiac function has been reported following concomitant treatment with Desferal and high doses of vitamin C (more than 500 mg daily). Cardiac dysfunction was reversible when vitamin C was discontinued. The following precautions should be taken when Desferal and vitamin C are used concomitantly: Vitamin C supplements should not be given to patients with cardiac failure.
Start treatment with vitamin C only after an initial month of regular treatment with Desferal.
Give vitamin C only if the patient is receiving Desferal regularly, ideally soon after setting up the pump.
Do not exceed a daily dose of 200 mg of vitamin C, given in divided doses.
Monitoring of cardiac function is advisable during such combined therapy.
Patients treated for chronic aluminum overload: In patients with aluminum-related encephalopathy, high doses of Desferal may exacerbate neurological dysfunction (convulsion), probably owing to an acute increase in circulating aluminum (see Adverse Reactions). Desferal may precipitate the onset of dialysis dementia. Pre-treatment with clonazepam has been reported to prevent this neurological deterioration. Also, treatment of aluminum overload may result in hypocalcemia and aggravation of hyperparathyroidism.
Urine discoloration: Excretion of the iron complex may cause reddish-brown discoloration of the urine.
Instructions for use and handling: Desferal should not be given in doses higher than recommended. The drug should not be given at concentrations higher than 95 mg/mL when given subcutaneously as this increases the risk of local reactions by the subcutaneous route (see Instructions for Use and Handling under Cautions for Usage). Where intramuscular use is the only option it may be necessary to use higher concentrations to facilitate the injection (see Incompatibilities under Cautions for Usage).
At the recommended concentration of 95 mg/mL, the reconstituted solution is clear, and colorless to slightly yellowish. Only clear solutions should be used. Opaque or cloudy solutions should be discarded. Due care must be taken with the injection technique.
For subcutaneous infusion, the needle should not be inserted too close to the dermis.
Driving and using machines: Patients experiencing dizziness or other central nervous disturbances, or impairment of vision or hearing, should refrain from driving a vehicle or operating machines (see Adverse Reactions).