ABSTRACT
【Objective】 To develop and verify a kinetic method for the determination of prekallikrein activator (PKA) content. 【Methods】 The optimal reaction conditions were determined by comparing the factors of pH and ionic strength of different sample dilution buffers, incubation time of each procedure, and incubation temperature. The accuracy, specificity, precision, linearity, stability and durability of the method were validated. 【Results】 The sample was diluted with 0.05 mol/L Tris-HCl buffer (pH8.5, containing 0.15 mol/L NaCl) and incubated by prekallikrein (PK) at 37℃ for 20 min. After that, the substrate S-2302 was added. Within 10 min before the measurement, the absorbance change rate reached △A405/min. The validation results indicated that the linear range of the method was (0.5~4.0)IU/mL, while the recovery of calibration standard was 96.9%~103.7% with the R2 value more than 0.99. The specificity test showed that human serum albumin, excipients of intravenous human immunoglobulin (pH4), low pH and protein content had no significant effect on the detection of PKA, The recovery rates of standard sample solution in the specificity experiment were 98.0% (0.9% sodium chloride solution), 95.3% (0.46% sodium caprylate solution), 96.7% (10% maltose solution, pH4.0), 94.0%(20%BSA), and 94.0%(5%BSA, pH4.0), respectively. The accuracy and precision of the method can meet requirements in the range between 0.5 and 4.0 IU/mL. The inter-batch recovery rate of quality control samples were between 96.4%~109.5% with the coefficients of variation(CV) between 0.2%~6.9%, while the intra-batch recovery rate were between 101.5%~102.9% with the CV between 2.6%~5.9%. The linearity, accuracy and precision of the assay can meet the requirements when PK and S-2302 were placed at room temperature for less than 6 hours, with the recovery rate of quality control samples between 94.9%~109.9%. The end-point method and kinetic method were used to determine the PKA in 20 batches of human serum albumin, and the consistency showed that there was no significant difference between the two methods(P>0.05). 【Conclusion】 A kinetic method for determination of PKA content with good linearity, specificity, accuracy, precision, stability and durability has been established. Compared with the method in ChP, the new method is more convenient, accurate and rapid to determine the content of PKA in human albumin and human immunoglobulin (pH4) for intravenous injection.
ABSTRACT
Iso-oncotic human serum albumin (HSA) is the primary replacement fluid of choice during therapeutic plasma exchange (TPE). Hypersensitivity reactions to HSA are rare, but require proper evaluation and management. In this article, we report two cases of hypersensitivity reactions to 5% HSA during TPE and discuss strategies to address this problem. The first case was a 60-year-old female patient, who was scheduled for TPE for treatment of recurrent focal segmental glomerulosclerosis after ABO-incompatible kidney transplantation. She developed a pruritic rash on her entire body during the first two sessions of TPE using 5% HSA. The third session was conducted using 500 mL normal saline, 1,000 mL 10% pentastarch, and 750 mL 5% HSA, where she eventually developed a pruritic rash when HSA was infused. There were no adverse events during the fourth and fifth session when fresh frozen plasma was used in place of HSA. The second case was a 50-year-old male patient diagnosed with optic neuritis, who was admitted for five sessions of TPE. The patient developed a pruritic rash on his entire body during the first session of TPE using 5% HSA. The patient experienced no adverse events during the following four sessions using fresh frozen plasma. Certain elements contained in HSA, such as albumin aggregates, prekallikrein activator, and caprylate-modified albumin, might be the reason for these hypersensitivity reactions. Careful selection of alternative replacement fluids is important to avoid premature termination of TPE procedures and secure optimal treatment options for patients.