Deferasirox pharmacokinetic evaluation in β-thalassaemia paediatric patients

An "ON-OFF" fluorescent sensor based on a novel zinc-based flower-like structured metal-organic framework for sequential detection of deferasirox and tigecycline

Deferasirox (DEF) is essential for patients with thalassemia requiring long-term transfusion therapy. Tigecycline (TIGE) is a first-line drug for the clinical treatment of complex, severe bacterial infections. The two drugs can be coordinated to treat Pseudomonas aeruginosa infections. Easy and efficient techniques for monitoring these two drugs in biological samples are few. Metal-organic framework (Zn-MOF) prepared from zinc nitrate hexahydrate and dithioglycolic acid has a flower structure. Interestingly, Zn-MOF can cause DEF to aggregate on it and induce DEF luminescence. The principle may be that Zn-MOF limits the vibration and rotation of DEF to avoid its nonradiative jump, which triggers aggregation-induced emission (AIE) and exhibits intense fluorescence. Further investigation revealed that TIGE could decompose Zn-MOF, thus alleviating the inhibitory effect of Zn-MOF on DEF and reducing the fluorescence intensity of DEF@Zn-MOF. A DEF/TIGE detection biosensor was created based on the fluorescence "turn-on" effect of Zn-MOF on DEF and the fluorescence "turn-off" effect of TIGE on DEF@Zn-MOF. The proposed technique was subsequently used to identify DEF/TIGE levels in pharmaceuticals and human plasma. The mean values for the percentage of the labeled amount of DEF/TIGE in DEF dispersible tablets/TIGE injection were 104.5 and 104.9%, respectively. The detection limits for the fluorescence detection of DEF and TIGE were 3.6 and 1.2 nM, respectively. This fluorescence assay is the first application of MOF to the simultaneous detection of DEF and TIGE and has the advantages of rapid sensitivity and high selectivity, providing a new strategy for drug detection.

Efficacy and Tolerability of Twice-Daily Dosing Schedule of Deferasirox in Transfusion-Dependent Paediatric Beta-Thalassaemia Patients: A Randomized Controlled Study

BACKGROUND

Deferasirox has proved good efficacy and acceptable safety for the management of thalassaemia patients. However, some patients are unresponsive or intolerant to once-daily administration of deferasirox even at a high dose. The current study evaluated the effectiveness and tolerability of twice-daily dosing of deferasirox among transfusion-dependent paediatric beta-thalassaemia patients.

METHODS

This prospective randomized single-blinded parallel study included all transfusion-dependent paediatric beta-thalassaemia patients prescribed with deferasirox, who visit the study site for their regular blood transfusions and follow-up. The enrolled patients were randomized into intervention and control groups by using a simple block randomization method. In the intervention group, the once-daily dosing of deferasirox was changed to twice-daily dosing with the same total daily dose. Whereas, in the control group, the patients continued with the once-daily deferasirox dosing. The serum ferritin levels of both groups were determined on the enrolment day and after 6 months of follow-up.

RESULTS

Forty-one patients were included for analysis. A statistically significant mean decrease in serum ferritin levels was detected in the intervention group, while the serum ferritin levels of the control group significantly increased from baseline. The twice-daily dosing of deferasirox was better tolerated by the thalassaemia patients when compared to once-daily dosing.

CONCLUSION

This study concludes that twice-daily dosing of deferasirox with the same total daily dose significantly enhances the iron chelation efficacy and tolerability among transfusion-dependent paediatric beta-thalassaemia patients when compared to once-daily regimen.

Effectiveness and tolerability of twice daily dosing of deferasirox in unresponsive and intolerant transfusion-dependent beta-thalassemia patients: A narrative review

Chronic iron overload in beta-thalassemia patients after continuous blood transfusions has caused notable morbidity and mortality in these patients. The once-a-day oral iron chelator, deferasirox has established efficacy and bearable safety in adults and pediatric thalassemia patients. It is now extensively used for the management of transfusional hemosiderosis. However, a number of studies have revealed a few patients continued to be none respondent or intolerant toward the once-a-day regimen of deferasirox even after the administration of maximum dose recommended by the World Health Organization. In the literature, there were three studies showing the boon of twice in a day dosing of deferasirox among transfusional-dependent beta thalassemia patients. Therefore, a nonsystematic review was conducted on above three studies to ascertain the enhanced effectiveness and tolerability of twice per day regimen of deferasirox with the same total dose as that of once daily regimen of deferasirox in unresponsive or intolerant transfusion-dependent beta-thalassemia (TDT) patients. All the above studies concluded that the twice per day regimen of deferasirox was more efficacious and tolerable among TDT patients when compared to the once-a-day regimen with the same total daily dose. Although there was a significant good results from these studies, there is a need to conduct either muticenter study or randomized control study in a larger number of patients for the better confirmation of the results as all the above studies were conducted in the small number of TDT patients.

Role of CYP1A1, ABCG2, CYP24A1 and VDR gene polymorphisms on the evaluation of cardiac iron overload in thalassaemia patients

OBJECTIVES

Iron-burden-induced arrhythmia and heart failure are among the leading causes of morbidity and mortality in β-thalassaemia major patients. T2* cardiac magnetic resonance remains the only reliable noninvasive method for the heart iron excess assessment. We explored the role of single nucleotide polymorphisms involved in vitamin D metabolism, transport and activity and in deferasirox (DFX) metabolism on cardiac iron burden.

PATIENTS AND METHODS

One hundred and five β-thalassaemia patients, treated with DFX, were enrolled in the present study. Drug plasma Ctrough was measured by a high-performance liquid chromatography-ultraviolet method. Allelic discrimination was carried out using the real-time PCR.

RESULTS

CYP1A1*1189 CC, ABCG2 421 GA, CYP24A1 8620 GG and VDR TaqI CC single nucleotide polymorphisms influenced T2* values. Age, serum ferritin, ABCG2 421 GA, ABCG2 1194 +928 TC/CC, CYP24A1 22776 TT and VDR TaqI TC/CC were retained in linear regression model.

CONCLUSION

Our results suggested, for the first time, the role of DFX and vitamin D pharmacogenetics on cardiac iron overload.

The effect of vitamin D pathway genes and deferasirox pharmacogenetics on liver iron in thalassaemia major patients

Monitoring and treating iron overload is crucial in transfusion-dependent thalassaemia patients. Liver stiffness measurement by transient elastography and T2* magnetic resonance imaging represent non-invasive ways to evaluate the adequacy of the iron chelation treatment. We explored the role of single nucleotide polymorphisms involved in vitamin D metabolism, transport and activity, and in deferasirox metabolism on liver iron burden parameters. One-hundred and five beta-thalassaemia patients, treated with deferasirox, have been enrolled. Drug plasma C_trough and AUC were measured by a HPLC-UV method. Allelic discrimination was performed by real-time PCR. Age, UGT1A1-364 CT/TT and CYP27B1 -1260 GT/TT positively predicted liver stiffness values. Deferasirox dose and serum ferritin negatively predicted T2* data, whereas age and CYP2D6 1457 GG genotype positively influenced these values. The discoveries of this research may be useful for personalized medicine and the proposed method could be applied in patients with hereditary hemochromatosis and myelodysplastic syndromes.