Randomized, Blinded, Placebo- and Positive-Controlled Crossover Study to Determine the Effect of Deferiprone on the QTc Interval in Healthy Subjects.

This study evaluated whether deferiprone, an oral iron chelator, acts to prolong the QT interval. Fifty healthy volunteers received single doses of each of the following: therapeutic dose of deferiprone (33 mg/kg), supratherapeutic dose (50 mg/kg), placebo, or moxifloxacin, a positive control known to significantly prolong QT interval. Following each dose, subjects underwent cardiac monitoring, pharmacokinetics assessments, and safety assessments. Based on the QT interval obtained using the Fridericia correction for heart rate (QTcF), the upper bound of the 1-sided 95% confidence interval of the mean difference between deferiprone and placebo was <10 milliseconds (the threshold of concern defined by authorities) at all time points for both doses: maximum difference of 3.01 milliseconds for the therapeutic dose and 5.23 milliseconds for the supratherapeutic dose. The difference in dQTcF between moxifloxacin and placebo demonstrated that the study was adequately sensitive to detect a significant prolongation of QTcF. The concentration-response correlation analyses revealed some weak but statistically significant trends of increase in dQTcF and ddQTcF with increasing exposure to deferiprone, but these trends should have no clinical consequence even at the recommended maximum dosage. In conclusion, there was no clinically meaningful effect on QTc interval following single therapeutic or supratherapeutic doses of deferiprone.

Effects of renal impairment on the pharmacokinetics of orally administered deferiprone.

AIMS: In light of the growing recognition of renal disease in thalassemia, it is important to understand the impact of renal impairment on the pharmacokinetics of iron chelators. This study evaluated the pharmacokinetics and safety of the iron chelator deferiprone (DFP) in subjects with renal impairment in comparison with healthy volunteers (HVs). METHODS: Thirty-two subjects were categorized into four groups based on degree of renal impairment: none, mild, moderate or severe, as determined by estimated glomerular filtration rate (eGFR). All subjects received a single oral dose of 33 mg kg(-1) DFP, provided serum and urine samples for pharmacokinetic assessment over 24 h and were monitored for safety. RESULTS: Renal clearance of DFP decreased as renal impairment increased. However, based on Cmax , AUC(0,t) and AUC(0,∞), there were no significant group differences in systemic exposure, because less than 4% of the drug was excreted unchanged in the urine. DFP is extensively metabolized to a renally excreted, pharmacologically inactive metabolite, deferiprone 3-O-glucuronide (DFP-G), which exhibited higher Cmax , AUC(0,t), AUC(0,∞) and longer tmax and t1/2 in the renally impaired groups compared with HVs. The Cmax and AUCs of DFP-G increased as eGFR decreased. Overall, 75%-95% of the dose was retrieved in urine, either as DFP or DFP-G, regardless of severity of renal impairment. With respect to safety, DFP was well tolerated. CONCLUSIONS: These data suggest that no adjustment of the DFP dosage regimen in patients with renal impairment is necessary, as there were no significant changes in the systemic exposure to the drug.

Deviating from safety guidelines during deferiprone therapy in clinical practice may not be associated with higher risk of agranulocytosis.

BACKGROUND: A risk associated with the iron chelator deferiprone is the development of neutropenia or agranulocytosis. Accordingly, the product label recommends weekly blood monitoring and immediate interruption of treatment upon detection of an absolute neutrophil count (ANC) <1.5 × 10(9)/L, out of concern that continued therapy might lead to a more severe drop. However, it is uncertain how these recommendations are followed under real-life conditions and, if they are not followed, whether continuation of therapy results in increased incidence of agranulocytosis. PROCEDURE: This non-interventional surveillance program assessed the monitoring of deferiprone therapy in clinical practice. A total of 294 patients with transfusion-dependent anemias received deferiprone, as monotherapy or with another chelator, for up to 1 year. The participating physicians were not given any instructions about treatment and monitoring beyond being referred to the information in the package insert. RESULTS: ANC monitoring was conducted at an average interval of 5 ± 4 weeks, and deferiprone was not always interrupted upon detection of neutropenia. One patient (0.3%) experienced agranulocytosis, and nine others (3%) experienced a total of 11 episodes of neutropenia. All neutropenia episodes resolved; median time to resolution was similar whether or not treatment was interrupted; and no case of neutropenia progressed to agranulocytosis. CONCLUSIONS: These data indicate that less frequent ANC monitoring and continuation of deferiprone therapy during neutropenia are not associated with prolonged neutropenia or with progression to agranulocytosis.