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Wednesday, 26 October 2011

New Drug Approvals 2011 - Pt. XXVII Deferiprone (FerriproxTM)

ATC code V03AC02 
Wikipedia Deferiprone

On October 14th, 2011 FDA announced the approval of Deferiprone (trade name: FerriproxTM) for the treatment of iron overload which is potentially fatal in patients with thalassemia. Deferiprone is an oral iron chelating agent, binding excess iron in the blood and thus making it available to excretion from the body. Thalassaemia is a inherited (mostly autosomal recessive) blood disease that can lead to anemia by causing the formation of abnormal hemoglobin molecules not able to properly bind and release oxygen. Thalassaemia (OMIM: 141800 (α-) / 141900 (β-)) is sub-classified according to which of the subunits of the hetero-tetrameric (2α/2β, UniProt: P69905 / P68871) hemoglobin is affected, contrary to sickle-cell anaemia (OMIM: 603903) which results exclusively from a specific mutation in the β subunit. The primary treatment of thalassaemia major, the severe form of β-thalassaemia, requires frequent blood transfusions to establish stable levels of functional hemoglobin but results in high levels of iron accumulating and impairing organ function. Thus, the secondary treatment aims on reducing the toxic iron levels by binding excess iron utilizing an iron chelating agent such as Deferoxamine (ChEMBL ID: CHEMBL556) requiring parenteral administration; Deferiprone has the desirable property of being orally available.

Deferiprone (3-hydroxy-1,2-dimethylpyridin-4(1H)-one, canonical SMILES: CN1C=CC(=O)C(=C1C)O, Standard InChI: InChI=1S/C7H9NO2/c1-5-7(10)6(9)3-4-8(5)2/h3-4,10H,1-2H3 , ChEMBL ID: CHEMBL556, CAS number: 30652-11-0, PubChem: CID 2972, ChemSpider: 2866) is a very simple synthetic small molecule with molecular weight of 139.152 Da, it has no rotatable bonds, two hydrogen bond acceptors, one hydrogen bond donor, ALogP of -0.14 and is thus fully rule-of-five compliant. 

Ferriprox is dosed as 500 mg tablets and administred orally three times daily in doses of 25 mg/kg to 33 mg/kg body weight (rounded to the nearest half-tablet), resulting in a daily molar dose of ~38-50 mmol for a 70 kg individual. Common adverse reactions include chromaturia, nausea, vomiting and abdominal pain, among others. Ferriprox is not suitable for pregnant or nursing women. Ferriprox reaches a maximum concentration (Cmax) of 20 mcg/mL, has an elimination half life (t1/2) of 1.9 hours and is excreted renally. The volume of distribution is 1.6 L/kg and 1 L/kg in thalassaemia patients and healthy subjects, respectively. Peak serum concentrations are reached 2 to 4 hours after administration.

Ferriprox has been issued a boxed warning for its potential to cause agranulocytosis/neutropenia, hematological disorders characterized by abnormally low numbers of white blood cells potentially leading to serious infections and death. 

Ferriprox is marketed and has been developed by Apotex

The full prescribing information can be found here. Prior to its approval in North America, Ferriprox has been approved and available in Europe and Asia for several years - approval in North America had been delayed considerably by safety concerns brought forward by a clinical researcher formerly involved in the clinical studies.

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