Deferiprone Other names: 3-hydroxy-1,2-dimethylpyridin-4-one

Chemical formula: C₇H₉NO₂  Molecular mass: 139.152 g/mol  PubChem compound: 2972

Interactions

Deferiprone interacts in the following cases:

End stage renal disease, severe hepatic impairment, liver fibrosis

There are no data available on the use of deferiprone in patients with end stage renal disease or severe hepatic impairment. Caution must be exercised in patients with end stage renal disease or severe hepatic dysfunction. Renal and hepatic function should be monitored in these patient populations during deferiprone therapy. If there is a persistent increase in serum alanine aminotransferase (ALT), interruption of deferiprone therapy should be considered.

In thalassaemia patients there is an association between liver fibrosis and iron overload and/or hepatitis C. Special care must be taken to ensure that iron chelation in patients with hepatitis C is optimal. In these patients careful monitoring of liver histology is recommended.

Aluminium-based antacids

Since deferiprone binds to metallic cations, the potential exists for interactions between deferiprone and trivalent cation-dependent medicinal products such as aluminium-based antacids. Therefore, it is not recommended to concomitantly ingest aluminium-based antacids and deferiprone.

Deferoxamine, deferasirox

The use of combination therapy should be considered on a case-by-case basis. The response to therapy should be assessed periodically, and the occurrence of adverse events closely monitored. Fatalities and life-threatening situations (caused by agranulocytosis) have been reported with deferiprone in combination with deferoxamine. Combination therapy with deferoxamine is not recommended when monotherapy with either chelator is adequate or when serum ferritin falls below 500 µg/l. Limited data are available on the combined use of deferiprone and deferasirox, and caution should be applied when considering the use of such combination.

Vitamin C

The safety of concurrent use of deferiprone and vitamin C has not been formally studied. Based on the reported adverse interaction that can occur between deferoxamine and vitamin C, caution should be used when administering deferiprone and vitamin C concurrently.

Decreased plasma Zn2+ concentration

Monitoring of plasma Zn2+ concentration, and supplementation in case of a deficiency, is recommended.

Discoloration of urine

Patients should be informed that their urine may show a reddish/brown discoloration due to the excretion of the iron-deferiprone complex.

Neurological disorders

Neurological disorders have been observed in children treated with more than 2.5 times the maximum recommended dose for several years but have also been observed with standard doses of deferiprone. Prescribers are reminded that the use of doses above 100 mg/kg/day are not recommended. Deferiprone use should be discontinued if neurological disorders are observed.

HIV positive, immunocompromised

No data are available on the use of deferiprone in HIV positive or in other immunocompromised patients. Given that deferiprone can be associated with neutropenia and agranulocytosis, therapy in immunocompromised patients should not be initiated unless potential benefits outweigh potential risks.

Pregnancy

There are no adequate data from the use of deferiprone in pregnant women. Studies in animals have shown reproductive toxicity. The potential risk for humans is unknown. Women of childbearing potential must be advised to avoid pregnancy due to the clastogenic and teratogenic properties of the medicinal product. These women should be advised to take contraceptive measures and must be advised to immediately stop taking deferiprone if they become pregnant or plan to become pregnant.

Nursing mothers

It is not known whether deferiprone is excreted in human milk. No prenatal and postnatal reproductive studies have been conducted in animals. Deferiprone must not be used by breast-feeding mothers. If treatment is unavoidable, breast-feeding must be stopped.

Carcinogenesis, mutagenesis and fertility

Fertility

No effects on fertility or early embryonic development were noted in animals.

Effects on ability to drive and use machines

Not relevant.

Adverse reactions


Summary of the safety profile

The most common adverse reactions reported during therapy with deferiprone in clinical trials were nausea, vomiting, abdominal pain, and chromaturia, which were reported in more than 10% of patients. The most serious adverse reaction reported in clinical trials with deferiprone was agranulocytosis, defined as an absolute neutrophil count less than 0.5 × 109/l, which occurred in approximately 1% of patients. Less severe episodes of neutropenia were reported in approximately 5% of patients.

List of adverse reactions

Adverse reaction frequencies: Very common (≥1/10), Common (≥1/100 to <1/10), not known (cannot be estimated from the available data).

Blood and lymphatic system disorders

Common: Neutropenia, Agranulocytosis

Immune system disorders

Frequency not known: Hypersensitivity reactions

Metabolism and nutrition disorders

Common: Increased Appetite

Nervous system disorders

Common: Headache

Gastrointestinal disorders

Very common: Nausea, Abdominal Pain, Vomiting

Common: Diarrhoea

Skin and subcutaneous tissue disorders

Frequency not known: Rash, Urticaria

Musculoskeletal and connective tissue disorders

Common: Arthralgia

Renal and urinary disorders

Very common: Chromaturia

General disorders and administration site conditions

Common: Fatigue

Investigations

Common: Increased liver enzymes

Description of selected adverse reactions

The most serious adverse reaction reported in clinical trials with deferiprone is agranulocytosis (neutrophils <0.5x109/l), with an incidence of 1.1% (0.6 cases per 100 patient-years of treatment). Data from pooled clinical studies in patients with systemic iron overload show that 63% of the episodes of agranulocytosis occurred within the first six months of treatment, 74% within the first year and 26% after one year of therapy. The median time to onset of the first episode of agranulocytosis was 190 days (ranged 22 days-17.6 years) and median duration was 10 days in clinical trials. A fatal outcome was observed in 8.3% of the reported episodes of agranulocytosis from clinical trials and post-marketing experience.

The observed incidence of the less severe form of neutropenia (neutrophils <1.5x109/l) is 4.9% (2.5 cases per 100 patient-years). This rate should be considered in the context of the underlying elevated incidence of neutropenia in thalassaemia patients, particularly in those with hypersplenism.

Episodes of diarrhoea, mostly mild and transient, have been reported in patients treated with deferiprone. Gastrointestinal effects are more frequent at the beginning of therapy and resolve in most patients within a few weeks without the discontinuation of treatment. In some patients it may be beneficial to reduce the dose of deferiprone and then scale it back up to the former dose. Arthropathy events, which ranged from mild pain in one or more joints to severe arthritis with effusion and significant disability, have also been reported in patients treated with deferiprone. Mild arthropathies are generally transient.

Increased levels of serum liver enzymes have been reported in some patients taking deferiprone. In the majority of these patients, the increase was asymptomatic and transient, and returned to baseline without discontinuation or decreasing the dose of deferiprone.

Some patients experienced progression of fibrosis associated with an increase in iron overload or hepatitis C.

Low plasma zinc levels have been associated with deferiprone in a minority of patients. The levels normalised with oral zinc supplementation.

Neurological disorders (such as cerebellar symptoms, diplopia, lateral nystagmus, psychomotor slowdown, hand movements and axial hypotonia) have been observed in children who had been voluntarily prescribed more than 2.5 times the maximum recommended dose of 100 mg/kg/day for several years. Episodes of hypotonia, instability, inability to walk, and hypertonia with inability of limb movement, have been reported in children in the post-marketing setting with standard doses of deferiprone. The neurological disorders progressively regressed after deferiprone discontinuation.

The safety profile of combination therapy (deferiprone and deferoxamine) observed in clinical trials, post-marketing experience or published literature was consistent with that characterized for monotherapy.

Data from the pooled safety database from clinical trials (1343 patient-years exposure to deferiprone monotherapy and 244 patient-years exposure to deferiprone and deferoxamine) showed statistically significant (p<0.05) differences in the incidence of adverse reactions based on System Organ Class for “Cardiac disorders”, “Musculoskeletal and connective tissue disorders” and “Renal and urinary disorders”. The incidences of “Musculoskeletal and connective tissue disorders” and “Renal and urinary disorders” were lower during combination therapy than monotherapy, whereas the incidence of “Cardiac disorders” was higher during combination therapy than monotherapy. The higher rate of “Cardiac disorders” reported during combination therapy than monotherapy was possibly due to the higher incidence of pre-existing cardiac disorders in patients who received combination therapy. Careful monitoring of cardiac events in patients on combination therapy is warranted.

The incidences of adverse reactions experienced by 18 children and 97 adults treated with combination therapy were not significantly different between the two age groups except in the incidence of arthropathy (11.1% in children vs. none in adults, p=0.02). Evaluation of rate of reactions per 100 patient-years of exposure showed that only the rate of diarrhoea was significantly higher in children (11.1) than in adults (2.0, p=0.01).

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