Optimizing the therapeutic window of sirolimus by monitoring blood concentration for the treatment of immune thrombocytopenia

Previous studies have demonstrated that sirolimus (SRL) is an effective agent for the treatment of refractory/relapsed (R/R) ITP. However, the therapeutic window of sirolimus in the treatment of ITP has not been established. As the toxicity of sirolimus increases with higher blood concentrations, it is crucial to determine the optimal therapeutic concentration of SRL for the treatment of ITP. Thus, in this study, we used a retrospective cohort of ITP patients treated with sirolimus to propose the therapeutic dosage window for sirolimus. A total of 275 laboratory results of SRL blood concentration from 63 ITP patients treated with SRL were analyzed retrospectively. The ITP patients were divided into five groups based on their SRL blood concentration: 0-4 ng/ml, 4-8 ng/ml, 8-12 ng/ml, 12-16 ng/ml and ≥16 ng/ml. In addition to the SRL blood concentration, platelet counts and adverse events that occurred during the first 6 weeks of SRL treatment were analyzed. These findings were then used to establish the decision matrix tables and ROC curves, which helped identify the therapeutic window of SRL. Based on the values and trends of true-positive rate (TPR) and false-positive rate (FPR) in the ROC curve, patients who achieved a SRL blood concentration of 4-12 ng/ml displayed a higher response rate compared to those with a SRL concentration of 0-4 ng/ml or ≥16ng/ml. Additionally, the response rate was better for patients with a SRL concentration of 8-12 ng/ml compared to 4-8 ng/ml. Adverse events were related to the concentration of SRL; however, there was no significant difference in the incidence of adverse events between the concentrations of 4-8 ng/ml and 8-12 ng/ml (P > .05). Regression analysis suggested that the concentration of SRL correlated with the patient's age, PLT count at the start of SRL administration, and the dose of SRL. It is suggested that the optimal blood concentration of SRL monotherapy for managing ITP is 8-12 ng/ml. This range may achieve a favorable balance between clinical efficacy and the severity of adverse events.

[Simultaneous determination of twelve antiepileptic drugs in serum by ultra high performance liquid chromatography-tandem mass spectrometry]

A sensitive, high-throughput method was established for the simultaneous determination of 12 antiepileptics in serum by ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The antiepileptics were gabapentin, lamotrigine, pregabalin, lacosamide, levetiracetam, topiramate, oxcarbazepine, clonazepam, sodium valproate, carbamazepine, phenobarbital and phenytoin sodium. Phenacetin and chlorzoxazone were used as internal standards. The antiepileptics and internal standards were extracted from serum by protein precipitation using acetonitrile as the precipitant. Chromatographic separation was achieved on an ACQUITY UPLC BEH C₁₈ column with a gradient mobile phase comprising 10 mmol/L ammonium formate aqueous solution and methanol (containing 10 mmol/L ammonium formate) at a flow rate of 0.4 mL/min. Detection was performed in multiple reaction monitoring mode with ion mode switching. The results showed good linear trends in their respective concentration ranges and the correlation coefficients (r²) were greater than 0.992. The spiked recoveries of the 12 antiepileptics in serum were 90.80%-114.0% at the three spiked levels. The intra-assay (n=6) and inter-assay (n=3) precisions were less than 13.2% and 14.8%, respectively. The method has high specificity and sensitivity, and it can be used for clinical blood concentration monitoring and pharmacokinetic studies of the 12 antiepileptics.