I. Athanasiadou1,2, A. Dokoumetzidis1, SC. Voss1, W. El Saftawy1, M. Al-Maadheed1, C. Georgakopoulos2, G. Valsami1
1Laboratory of Biopharmaceutics & Pharmacokinetics, Faculty of Pharmacy, National & Kapodistrian University of Athens, Panepistimiopolis-Zographou 15771, Athens, Greece, 2Anti Doping Lab Qatar, P.O. Box 27775, Doha, Qatar
Introduction/Objectives: Excessive fluid intake, i.e., hyperhydration may be adopted by athletes as a masking method during anti-doping sample collection to influence the excretion patterns of doping agents and, therefore, manipulate their detection [1]. The aim of this exploratory study was to assess the hyperhydration effect on serum and urinary pharmacokinetic (PK) profile and detection sensitivity of recombinant human erythropoietin (rHuEPO)in athletes [2].
Methods: Seven healthy physically active non-smoking Caucasian males were participated in a 31-day clinical study comprised a baseline (Days 0, 1‒3, 8‒10) and a drug phase (Days 15‒17, 22‒24, 29‒31). Epoetin beta was administered subcutaneously at a single dose of 3000 IU on Days 15, 22 and 29. This provided a total of 259 blood samples. Hyperhydration was applied in the morning on three consecutive days (Days 1‒3, 8‒10, 22‒24, 29‒31), i.e., 0, 24 and 48 hours after first fluid ingestion (water and a commercial sports drink, 20 mL/kg BW). Population PK modeling was performed on the measured serum concentrations after rHuEPO administration using Monolix® software version 2018a (Lixoft, Batiment D, Antony, France), while non-compartmental analysis (NCA) PK analysis was performed on the measured serum and urinary EPO concentrations using the Phoenix® version 8.0 PK/PD software package (Certara, Princeton, NJ, USA). One and two compartment models together with various absorption models which included zero and first order, separately and combined, with and without lag time, as well as different error models were tested. Interindividual variability (IIV) was considered as univariate log-normal for all the parameters. Age and BW were tested as covariates on the parameters of the final model.
Results: Serum EPO concentration-time profiles were best described by a one compartment (1-CP) PK model with zero order absorption, parameterized as total clearance (CL), volume of distribution (Vd) and time for zero order absorption. An EPO constant baseline parameter, to account for the endogenous EPO concentration which is measured with the exogenously administered rHuEPO, was introduced. Delayed absorption was observed after hyperhydration and, therefore, lag time was introduced in the PK model. A multiplicative residual model error was used in all cases. No covariates were found to improve the base model, probably due to the small number of individuals enrolled in the study. Regarding the estimated PK(RSE%) parameters, apart from the observed delayed absorption, with Tlag 1.4(33.3) h and 0.7(31.3) h after water and sports drink hyperhydration, a trend for decreasing Vd from 63.1(27.2) L to 53.4(29.1) L and 24.7(37.2) L and increasing CL from 0.775(14.6) L/h to 2.22(40.8) L/h and 2.03(25.5) L/h after hyperhydration was observed, mainly after sports drink consumption. The respective IIV(RSE%) was 59.3(46.5) and 39.1 (76.3) for Tlag (water, sports drink hyperhydration), 67.1(29.9), 66.2(34.7) and 80.3(33.3) for Vd (baseline, water, sport drink hyperhydration), and 14.5(73.3), 98.2(33.5) and 63.1(29.9) for CL (baseline, water, sport drink hyperhydration). The residual error was less than 30% in all cases. No significant difference (P>0.05) due to hyperhydration for any of the serum PK parameters calculated by NCA was observed. Results showed no significant difference (P>0.05) on serum or urinary EPO concentrations under hyperhydration conditions. Renal excretion of endogenous and rHuEPO, as reflected on the urinary cumulative amount, was increased approximately twice after hyperhydration and this supports the non-significant difference on the urinary concentrations.
Conclusions: Serum and urinary EPO concentration-time profiles remained unaffected after excessive fluid intake (water or sports drink). Serum and urinary PK parameters of a WADA prohibited substance were utilized for the first time in conjunction to the urinary concentration-time profiles as a tool for doping detection. NCA analysis was applied to calculate basic PK parameters, while compartmental PK modeling was necessary for the accurate estimation of EPO serum CL considering the existence of the endogenous EPO levels. Analysis of serum and urine samples was able to detect rHuEPO up to 72 hours after drug administration. The detection window of rHuEPO remained unaffected after water or sports drink ingestion. Hyperhydration had no effect on the detection sensitivity of EPO either in serum or urine samples.
References:
[1] World Anti-Doping Agency. WADA Technical Document – TD2014EPO (ver. 1.0): Harmoniza-tion of analysis and reporting of erythropoiesis stimulating agents (ESAs) by electrophoretic techniques, 2014. https://www.wada-ama.org/sites/default/files/resources/files/WADA-TD2014EPO-v1-Harmonization-of-Analysis-and-Reporting-of-ESAs-by-Electrophoretic-Techniques-EN.pdf.
[2] Athanasiadou I, Dokoumetzidis A, Voss S, El Saftawy W, Al-Maadheed M, Valsami G, Georgakopoulos C. Hyperhydration effect on pharmacokinetic parameters and detection sensitivity of recombinant human erythropoietin in urine and serum doping control analysis of males, J Pharm Sciences. 2019; Accepted manuscript.
[3] Mínguez R, Conejo AJ, García-Bertrand R, Efron B, Tibshirani RJ. Reliability and decomposi-tion techniques to solve certain class of stochastic programming problems. Reliab Eng Syst Safe. 2011;96:314‒23.
Reference: PAGE 28 (2019) Abstr 8809 [www.page-meeting.org/?abstract=8809]
Poster: Drug/Disease Modelling - Other Topics