A Comparative Pharmacokinetic Study of Recombinant Human Serum Albumin With Human Serum Albumin

PharmacologyThe Journal of ClinicalDOI: 10.1177/00912700073105492008; 48; 203 J. Clin. Pharmacol.Kunihiko Ohnishi, Atsuhiro Kawaguchi, Shunji Nakajima, Hiroyuki Mori and Takahiro UeshimaPlasma-derived Human Serum Albumin in Patients With Liver Cirrhosis A Comparative Pharmacokinetic Study of Recombinant Human Serum Albumin With/cgi/content/abstract/48/2/203The online version of this article can be found at:Published by:On behalf of:American College of Clinical Pharmacologycan be found at:The Journal of Clinical Pharmacology Additional services and information for /cgi/alerts Email Alerts: /subscriptions Subscriptions: /journalsReprints.nav Reprints: /journalsPermissions.nav Permissions:/cgi/content/abstract/48/2/203#BIBL SAGE Journals Online and HighWire Press platforms): (this article cites 24 articles hosted on the Citations© 2008 American College of Clinical Pharmacology. All rights reserved. Not for commercial use or unauthorized distribution. at MCMASTER UNIV LIBRARY on February 2, 2008 Downloaded fromJ Clin Pharmacol 2008;48:203-208203© 2008 American College of Clinical Pharmacology. All rights reserved. Not for commercial use or unauthorized distribution. at MCMASTER UNIV LIBRARY on February 2, 2008 Downloaded from204•J Clin Pharmacol 2008;48:203-208methylotrophic Pichia pastoris , developed using recombinant DNA technology, employing a success-fully established high-producer strain and an origi-nally developed high-level purification system.10-12Structural and physicochemical properties revealed rHSA identical to pHSA,13-16and pharmacokinetic profiles were deemed similar in animal studies.17,18Clinically, rHSA demonstrated efficacy and safety equivalent to pHSA during a phase III study in patients with ascites due to liver cirrhosis.19Other clinical studies indicated efficacy and safety in hem-orrhagic shock, nephrosis, burns, acute abdomen,poor-risk before surgery, and post–open heart surgery patients.20In this study, we evaluated the pharmacokinetic profiles of rHSA in liver cirrhosis patients in compar-ison to pHSA using serum albumin concentrations.STUDY DESIGNThis study was conducted at Ohnishi Hospital and the protocol approved by the institutional review board in compliance with good clinical practice guidelines.PatientsPrior written informed consent was obtained from 22 patients with liver cirrhosis, who fulfilled the inclusion and exclusion criteria and enrolled into the study, which was conducted from September 2002 to March 2003.Liver cirrhosis patients without ascites or edema,aged 20 to 75 years inclusive, who could be admitted for the study period were eligible for participation.The following exclusion criteria were applied:patients who received blood transfusions or plasma protein products within 3 months before screening;a total bilirubin of 3.0 mg/dL or more; renal dys-function manifested by serum creatinine levels of 4.0 mg/dL or more; prothrombin time (PT) of less than 50%; hepatocellular carcinoma (HCC) verified by tumor embolism in the portal vein (main trunk or primary/secondary branch), inferior vena cava, or main trunk of the hepatic vein; cardiac functions rated class III or IV according to the New York Heart Association (NYHA) classification; history of shock or hypersensitivity to any ingredient of pHSA prod-ucts; patients scheduled to undergo invasive testing or treatment for underlying diseases or complica-tions (eg, HCC, gastric/esophageal varices) during the study period; hepatic encephalopathy (coma scale class II or more severe) at receipt of informed consent; a positive prick test result for rHSA; femalepatients who were pregnant, nursing, could be pregnant,or intended to become pregnant during the study period; and other patients deemed ineligible for par-ticipation by the investigators.MATERIALS AND METHODS Administration Method and DosageRecombinant human serum albumin (recombinant albumin 25%, Bipha Corporation, Chitose, Japan) or pHSA (HSA 25%, Benesis Corporation, Osaka, Japan)were administered intravenously at a dose of 25 g once daily via infusion pump at 12.5 g/hr (50 mL/hr during a 2-hr period) for 3 days, and examinations were performed until day 8.Assignment and Sample SizeTo minimize intergroup bias in baseline values of serum albumin concentrations, assignment was dynamically conducted, using only this factor, by the minimization method according to concentra-tions measured 1 day prior to administration (day –1) by a third party (Bellsystem24 Inc., Tokyo,Japan). Multiple factors were not incorporated, as the study population was small. Because serum albumin concentration is the only objective parame-ter used to assess the primary endpoint, an open-label design was selected.Half-life (t 1/2) of albumin is known to be long, 15 to 19 days,21-23thus parallel-group was chosen versus crossover as the study design. Sample size was esti-mated at 10 patients per group according to the Guidelines for Bioequivalence Testing of Generic Drugs 24and set at 11 patients, taking dropouts into con-sideration. Serum albumin concentrations observed in a previous phase III study in patients with ascites due to liver cirrhosis and the data collected until day 7were used to calculate the area under the curve (AUC)in each group. Based on the AUC (g·hr/dL) (497.5 ±62.1, 47 [mean ±SD, number of subjects] in the rHSA group, and 514.4 ±69.3, 45 in the pHSA group),power was calculated when 90% confidence interval (CI) fell within 80% to 125% of the AUC, and indi-cated 10 patients as sufficient to provide 90% power to detect bioequivalence.Prohibited Concomitant Medications and TherapiesConcomitant use of the following medications and thera-pies was prohibited: blood transfusion or administration© 2008 American College of Clinical Pharmacology. All rights reserved. Not for commercial use or unauthorized distribution. at MCMASTER UNIV LIBRARY on February 2, 2008 Downloaded fromof plasma protein products, other investigational products, invasive testing, or treatment for HCC (excision, percutaneous ethanol injection therapy [PEIT], transcatheter arterial embolization [TAE] ther-apy, transcatheter arterial injection [TAI] of carcinostat-ics, microwave coagulation therapy [MCT], high frequency coagulation therapy [radiofrequency wave],transcatheter contrast imaging, etc), sclerotherapy for gastric or esophageal varices, ligation of varices, or endoscopy from receipt of consent to day 8. Concomitant use of diuretics was permitted only at a stable dosage and dose regimen during the study period.Observation, Examination, and Assessment Items Patients were admitted on day –1, treated with rHSA or pHSA from days 1 to 3, and observed until dis-charge on day 8. Serum albumin concentrations were measured using the bromcresol green (BCG) method at Mitsubishi Chemical Medience Corporation (Tokyo, Japan), and concentrations monitored on day –1, immediately predose and postdose during the treatment phase (days 1-3), and daily for the observation period (days 4-8). To assess safety,patients were observed for any clinical signs and symptoms from days 1 to 8. In addition, laboratory tests (hematology and urinalysis) were conducted on days –1, 4, and 8, and vital signs recorded predose and postdose during the treatment phase and once daily during the observation period.Statistical AnalysisPrimary analysis was performed on AUC using the trapezoidal method from day 1 predose to day 8 (168 hr).Since C max of intravenous HSA administrations may not be evaluated, as with oral agents, AUC was the other major parameter that could be considered a primary endpoint for bioequivalence and C max another majorparameter calculated as reference data. If the 90% CI for the difference in mean log-transformed AUC fell within log (0.8) and log (1.25), both products were determined as bioequivalent.24Analyses were per-formed using the statistical software SAS Version 8.2(SAS Institute Inc., Cary, North Carolina).RESULTSDemographic and Baseline CharacteristicsIn both groups comprising 11 patients each, the inves-tigational product was administered as specified in the protocol, and all patients were included in the analyses.Serum albumin concentrations on day –1 were 3.34±0.43 g/dL (mean ±SD) in the rHSA group, and 3.31±0.43 g/dL in the pHSA group, suggesting patients were equally assigned to treatment groups by the min-imization method (Table I). Background characteris-tics, such as age and weight, excluding gender, were comparable between the 2 groups. An intergroup gender difference was found between the all-male rHSA group and the 7-male/4-female pHSA group.Analyses of Serum AlbuminConcentrations and BioequivalenceIn both groups, changes in plasma concentrations showed a similar pattern after each intravenous dose (repeated for 3 days) and after termination of admin-istration, with similar serum albumin concentration-time profiles (Figure 1).Geometric mean AUC 0-168hr (g·hr/dL) was 637.12 in the rHSA group, and 635.93 in the pHSA group. The difference in AUC 0-168hr was 0.0008 ±0.0191, and 90%CI ranged from –0.0321 to 0.0337 (92.9%-108.1%),falling within the acceptable bioequivalence range,PHARMACOKINETICS/SPECIAL POPULATIONS205© 2008 American College of Clinical Pharmacology. All rights reserved. Not for commercial use or unauthorized distribution. at MCMASTER UNIV LIBRARY on February 2, 2008 Downloaded from206•J Clin Pharmacol 2008;48:203-208–0.0969 to 0.0969 (log [0.8] to log [1.25]), indicating bioequivalence between rHSA and pHSA (Table II).Geometric mean C max (g/dL) was 4.16 in the rHSA group, and 4.19 in the pHSA group. The difference in C max was –0.0030 ±0.0174, and 90% CI ranged from –0.0330 to 0.0269 (92.7%-106.4%) (Table II).SafetyThree adverse events were observed in 2 patients from the pHSA group among the 22 patients exam-ined. No serious or allergic adverse events were observed in either group. A single event of insomnia was reported in a male patient from the pHSA group and was considered moderate, resolved by day 8with treatment using an antianxiety drug; it was regarded as being unrelated to the investigational product and caused by the environmental change from hospitalization. Two abnormal laboratory changes observed in 1 male patient from the pHSA group (increase in BUN and serum creatinine levels:BUN values on days –1, 4, and 8 were 19, 43, and 52mg/dL , respectively, and serum creatinine levels were 1.0, 2.4, and 1.9 mg/dL , respectively) being treated concomitantly with 2 diuretic agents were possibly related to the investigational product.Exogenous albumin increased total serum albumin Figure 1.Serum albumin concentration-time profile after repeated intravenous administration of 25 g rHSA or pHSA at 0, 24, and 48hours (mean ± SD).© 2008 American College of Clinical Pharmacology. All rights reserved. Not for commercial use or unauthorized distribution. at MCMASTER UNIV LIBRARY on February 2, 2008 Downloaded fromincreases in serum albumin concentration-time pro-files were observed in both the rHSA and pHSA groups after administration from days 1 to 3, and par-allel concentration-time profiles were maintained till day 8 with a small linear decrease (Figure 1). The dif-ference in mean log-transformed serum albumin AUC 0-168hr was 0.0008 ±0.0191 (90% CI: 92.9%-108.1%), indicating bioequivalence between rHSA and pHSA (Table II). C max was the other major para-meter used in the investigation of bioequivalence. In this study, C max was calculated as reference data since HSA was administered intravenously. The 90% CI for the difference, from 92.7% to 106.4%, lies within the bioequivalence range.On the other hand, it is difficult to estimate other pharmacokinetic parameters such as t 1/2 accurately in this study, as albumin is an endogenous protein with a long t 1/2, and a small rise of approximately 1.0 g/dL in concentration after multiple dosing is also insufficient. As reference data, we calculated the t 1/2using the least square method from day 3postdose to day 8. Since t 1/2of 2 subjects (77.5 and 209.2 days) was 3 times larger than the reference data (15 to 19 days 21-23), this data was excluded from this analysis. The t 1/2was 31.1 ±7.0 day (n =10) in the nHSA group, and 29.6 ±6.2 (n =10) in the rHSA group. We also estimated t 1/2from day 3 postdose to day 7. It is better to calculate t 1/2excluding data on day 8 because serum albumin concentration between day 7 and day 8 are close and plateaued (Figure 1). The t 1/2was 23.8 ±8.3 day (n =11) in the nHSA group, and 23.9 ±7.2 (n =10) in the rHSA group. One t 1/2value in the rHSA group was excluded because the calculated t 1/2was negative.The differences between these values were not remarkable. To evaluate the t 1/2of albumin accu-rately, a long-term radioisotope study would be needed to assess the elimination phase of albumin.Patient demographics and baseline characteristics generally showed no remarkable bias, including baseline serum albumin concentrations, except for gender. Although this difference existed between the rHSA (11 male) and pHSA (7 male; 4 female) groups,in post-hoc analysis (P =.0902, Fisher), intergroup analysis exclusively among male patients provided a similar 90% CI (93.3%-111.9%) compared to pri-mary analysis results. Since weight differs by gender,exploratory bioequivalence analysis using adjusted weight as a covariate showed no significant differ-ences between the groups (90% CI: 92.7%-108.4%).In addition, baseline adjustments were made for the AUC 0-168hr and C max as serum albumin is an endogenous protein. The following parameters were calculated after subtracting immediately predose (baseline) values. Baseline-adjusted geometric mean AUC 0-168hr (g·hr/dL ) was 99.96 and 106.74 in the rHSA and pHSA groups, respectively, while differ-ence in mean AUC 0-168hr was –0.0285 ±0.0333 (90%CI: 82.0%-106.9%). Baseline adjusted geometric mean C max (g/dL) was 0.96 and 1.04 in the rHSA and pHSA groups, respectively, and difference in mean C max was –0.0383 ±0.0276 (90% CI: 82.0%-102.2%).These differences do not contradict bioequivalence.Overall, both rHSA and pHSA were safe and well tolerated in the study. In the pHSA group, insomnia (unrelated) was reported in 1 patient, and increases in BUN and serum creatinine levels (possibly related) were observed in 1 patient. No adverse events of clinical concern were observed in eithertreatment group. Examination of safety data obtainedPHARMACOKINETICS/SPECIAL POPULATIONS207© 2008 American College of Clinical Pharmacology. All rights reserved. Not for commercial use or unauthorized distribution. at MCMASTER UNIV LIBRARY on February 2, 2008 Downloaded from208•J Clin Pharmacol 2008;48:203-208from a previous phase III study resulted in little adverse reaction.19Recombinant human serum albumin is a high purity, virus-free albumin product based on recombi-nant DNA technology without using blood-derived components in the manufacturing process.10-12It is successfully being mass produced on a commercial basis, suggesting a stable supply can be realized with-out using finite human blood, and that limitation on plasma procurement can be overcome.These results indicate bioequivalence between rHSA and pHSA, and can be considered a possible alternative in the clinical environment.Financial disclosure: This study was sponsored by Mitsubishi Tanabe Pharma Corporation.REFERENCES1.Tullis JL . Albumin. Guidelines for clinical use. JAMA.1977;237:460-463.2. Vermeulen LC, Ratko TA, Erstad BL, Brecher ME, Matuszewski KA. 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