Orally effective iron chelating agent:

Ans: b (Defriprone) Ref: Tripathi, 6th ed, p. 868; Katzung, 10th ed, p. 945Defriprone: It is an orally active iron chelator. Oral defriprone is somewhat less effective alternative to injected desferroxamine.DEFERASIROXDeferasirox is a tridentate chelator with a high affinity for iron and low affinity for other metals, e.g., zinc and copper. It is orally active and well absorbed. In the circulation it binds iron, and the complex is excreted in the bile.Deferasirox was recently approved for the oral treatment of iron overload caused by blood transfusions.DESFERIOXAMINEDeferoxamine is isolated from Streptomycespilosus. It binds iron very avidly. It is the parenteral chelator of choice for iron poisoning. Deferoxamine plus hemodialysis may also be useful in the treatment of aluminum toxicity in renal failure.Deferoxamine is poorly absorbed when administered orally and may increase iron absorption when given by this route. It should therefore be administered intramuscularly or, preferably, intravenously.The iron-chelator complex is excreted in the urine, often turning the urine an orange-red color.Rapid intravenous administration may result in hypotension. Adverse idiosyncratic responses such as flushing, abdominal discomfort, and rash have also been observed. Pulmonary complications (e.g., acute respiratory distress syndrome) have been reported in some patients undergoing deferoxamine infusions lasting longer than 24 hours, and neurotoxicity and increased susceptibility to certain infections (e.g., with Yersinia enterocolitica and Mucormycosis) have been described after long-term therapy of iron overload conditions (e.g., thalassemia major).PENICILLAMINE (D-DIMETHYLCYSTEINE)Penicillamine is used chiefly for treatment of poisoning with copper or to prevent copper accumulation, as in Wilson's disease (hepatolenticular degeneration). It is also used occasionally in the treatment of severe rheumatoid arthritis. Its ability to increase urinary excretion of lead and mercury had occasioned its use as outpatient treatment for intoxication with these metals, but succimer, with its stronger metal-mobilizing capacity and lower side effect profile, has generally replaced penicillamine for these puiposes.Adverse effects have been seen in up to one third of patients receiving penicillamine. Hypersensitivity reactions include rash, pruritus, and drug fever, and the drug should be used with extreme caution, if at all, in patients with a history of penicillin allergy. Nephrotoxicity with proteinuria has also been reported, and protracted use of the drug may result in renal insufficiency. Pancytopenia has been associated with prolonged drug intake. Pyridoxine deficiency is a frequent toxic effect of other forms of the drug but is rarely seen with the D form. An acetylated derivative, /V-acetylpenicillamine, has been used experimentally in mercury poisoning and may have superior metal-mobilizing capacity, but it is not commercially available.EDETATE CALCIUM DISODIUM (ETHYLENEDIAMINETETRAACETIC ACID Ethylenediaminetetraacetic acid is an efficient chelator of many divalent and tri valent metals in vitro. To prevent potentially life-threatening depletion of calcium, the drug should only be administered as the calcium disodium salt..EDTA should be administered by intravenous infusion..In patients with renal insufficiency, excretion of the drug--and its metal-mobilizing effects--may be delayed.Indications & ToxicityEdetate calcium disodium is indicated chiefly for the chelation of lead, but it may also have utility in poisoning by zinc, manganese, and certain heavy radionuclidesBecause the drug and the mobilized metals are excreted via the urine, the drug is relatively contraindicated in anuric patients. Nephrotoxicity from EDTA has been reported.