Low membrane protein sulfhydrils but not G6PD deficiency predict ribavirin-induced hemolysis in hepatitis C

Abstract

Hemolysis is a frequent adverse effect of ribavirin (RBV). It has been suggested that oxidative stress plays a role, but mechanisms and predictive risk factors for severe forms remain unknown. Markers of redox status were determined in erythrocytes of 34 patients with hepatitis C-four of them with glucose-6-phosphate-dehydrogenase (G6PD) deficiencybefore and during treatment with RBV and interferon (IFN) and were compared with 10 healthy control subjects. In addition, erythrocytes were incubated with RBV, and the effects of dipyridamole (DPD), diethylmaleate (DEM), and glutathione ester (GSHE) were studied in vitro. Of the 30 patients without G6PD deficiency who were treated with RBV and IFN-␣, five developed major hemolysis (⌬ hemoglobin > 6 g/dL) and 25 developed minor hemolysis (⌬ hemoglobin < 2.5 g/dL). Patients with major hemolysis had lower median pretreatment values of membrane protein sulfhydrils than patients with minor hemolysis (28.4 vs. 36.7 nmol/mg, P < .001). Erythrocytes of G6PD-deficient patients were not more susceptible to RBV-induced hemolysis. In in vitro incubations of erythrocytes, DEM enhanced the RBV-induced decrease of glutathione, protein sulfhydrils, and osmotic resistance. Supplementation of GSHE and DPD prevented the RBV-induced decrease in osmotic resistance, adenosyl triphosphate (ATP), and 2,3-diphosphoglycerate (DPG), the loss of glutathione and protein sulfhydrils, and the formation of thiobarbituric acid reactive substances (TBARs). In conclusion, the data indicate that low membrane protein sulfhydrils prior to therapy but not G6PD deficiency are predictive of RBV-induced major hemolysis. In vitro, GSHE and DPD reduce the RBV-associated oxidative stress in erythrocytes and prevent the increase in osmotic fragility, suggesting that these compounds might decrease the risk of hemolysis in patients. (HEPATOLOGY 2004;39:1248 -1255 R ibavirin (RBV) is a synthetic nucleoside analogue used in the treatment of chronic hepatitis C in combination with interferon (IFN)-␣. The addition of RBV has increased the probability of sustained response to approximately 40% if combined with conventional IFN 1,2 and to over 50% if combined with pegylated IFN. 3 RBV actively enters cells by way of the es-nucleoside membrane transporter 4 and subsequently undergoes phosphorylation at the expense of adenosyl triphosphate (ATP). 5,6 In contrast to nucleated cells such as hepatocytes, phosphorylation is irreversible in the anucleate erythrocytes, and phosphorylated RBV accumulates because it cannot be exported by the nucleoside carrier. Therefore, the concentration of RBV in erythrocytes is 50-to 70-fold higher than the therapeutic plasma concentration of 9 -15 M. 5,7,8 The high concentration of RBV in erythrocytes is probably responsible for the hemolysis occurring during RBV therapy. A decrease in hemoglobin (HB) is frequently observed in patients who receive RBV,

Effects of Oral Supplementation of Vitamin E on Fragility of RBC in Hemolytic Anemic Patients with G6PD Deficiency

“…These findings are in consistent with those of some other researchers of different countries [14][15][16] . On the contrary, no remarkable change in osmotic fragility of RBC and red cell indices were reported.…”

“…An increase in osmotic fragility of RBC may occur in hemolytic anemia with G6PD deficiency 14 . Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) may also decrease in this group of hemolytic anemic patients 15,16 .…”

Red Blood Cell Fragility and Reticulocyte Count in Hemolytic Anemic Patients with and Without G-6PD Enzyme Deficiency

“…These findings are consistent with those of some investigators of different countries 23 . On the contrary, no remarkable change in osmotic fragility of RBC had also been reported by some other group investigators 24 .…”

Impact of genetic SLC28 transporter and ITPA variants on ribavirin serum level, hemoglobin drop and therapeutic response in patients with HCV infection

“…Higher ITP concentrations are believed to protect against RBV induced ATP depletion and consequently anemia [13][14] by substituting for erythrocyte GTP in the biosynthesis of ATP [15]. Interestingly, in the above-mentioned study there was no association between these polymorphisms and treatment response, which would be expected based on such a mechanism.…”