Effect of hyperhydration on the pharmacokinetics and detection of orally administered budesonide in doping control analysis.

The aim of the present study was to investigate if hyperhydration could influence the excretion and subsequent detection of budesonide (BDS) and its main metabolites (6ß-hydroxy-budesonide and 16α-hydroxy-prednisolone) during doping control analysis by leading to concentrations below the WADA reporting level (30 ng/mL). The influence of hyperhydration on the plasma and urinary pharmacokinetic (PK) profiles of BDS and metabolites was also examined. Seven healthy physically active non-smoking Caucasian males participated in a 15-day clinical study. BDS was administered orally at a single dose of 9 mg on Days 1, 7, and 13. Hyperhydration was applied in the morning on two consecutive days, that is, 0 and 24 hours after first fluid ingestion. Water and a commercial sports drink were used as hyperhydration agents (20 mL/kg body weight). Results showed no significant difference (P > 0.05, 95% CI) on plasma or urinary PK parameters under hyperhydration conditions for all the analytes. However, significant differences (P < 0.05, 95% CI) due to hyperhydration were observed on the urinary concentrations of BDS and metabolites. To compensate the dilution effect due to hyperhydration, different adjustment methods were applied based on specific gravity, urinary flow rate, and creatinine. All the applied methods were able to adjust the concentration values close to the baseline ones for each analyte; however, specific gravity was the optimum method in terms of effectiveness and practicability. Furthermore, no masking of the detection sensitivity of BDS or its metabolites was observed due to hyperhydration either in plasma or urine samples.

Hyperhydration Effect on Pharmacokinetic Parameters and Detection Sensitivity of Recombinant Human Erythropoietin in Urine and Serum Doping Control Analysis of Males.

Excessive fluid intake, that is, hyperhydration, may be adopted by athletes as a masking method during antidoping sample collection to influence the excretion patterns of doping agents and, therefore, manipulate their detection. The aim of this exploratory study was to assess the hyperhydration effect on the detection sensitivity of recombinant human erythropoietin (rHuEPO) by sodium N-lauroyl sarcosinate ("sarkosyl") polyacrylamide gel electrophoresis analysis. The influence of hyperhydration on the serum and urinary pharmacokinetic (PK) profiles of rHuEPO was also investigated. Seven healthy physically active nonsmoking Caucasian males participated in a 31-day clinical study comprising a baseline (days 0, 1-3, and 8-10) and a drug phase (days 15-17, 22-24, and 29-31). Epoetin beta was administered subcutaneously at a single dose of 3000 IU on days 15, 22, and 29. Hyperhydration was applied in the morning on 3 consecutive days (days 1-3, 8-10, 22-24, and 29-31), that is, 0, 24, and 48 h after first fluid ingestion. Water and a commercial sports drink were used as hyperhydration agents (20 mL/kg body weight). Serum and urinary concentration-time profiles were best described by a one-compartment PK model with zero-order absorption. Delayed absorption was observed after hyperhydration and, therefore, lag time was introduced in the PK model. Results showed no significant difference (p > 0.05) on serum or urinary erythropoietin concentrations under hyperhydration conditions. A trend for decreasing volume of distribution and increasing clearance after hyperhydration was observed, mainly after sports drink consumption. However, no significant differences (p > 0.05) due to hyperhydration for any of the serum PK parameters calculated by noncompartmental PK analysis were observed. Renal excretion of endogenous erythropoietin and rHuEPO, as reflected on the urinary cumulative amount, was increased approximately twice after hyperhydration and this supports the nonsignificant difference on the urinary concentrations. Analysis of serum and urine samples was able to detect rHuEPO up to 72 h 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.

Chaos synchronization and Nelder-Mead search for parameter estimation in nonlinear pharmacological systems: Estimating tumor antigenicity in a model of immunotherapy.

In mathematical pharmacology, models are constructed to confer a robust method for optimizing treatment. The predictive capability of pharmacological models depends heavily on the ability to track the system and to accurately determine parameters with reference to the sensitivity in projected outcomes. To closely track chaotic systems, one may choose to apply chaos synchronization. An advantageous byproduct of this methodology is the ability to quantify model parameters. In this paper, we illustrate the use of chaos synchronization combined with Nelder-Mead search to estimate parameters of the well-known Kirschner-Panetta model of IL-2 immunotherapy from noisy data. Chaos synchronization with Nelder-Mead search is shown to provide more accurate and reliable estimates than Nelder-Mead search based on an extended least squares (ELS) objective function. Our results underline the strength of this approach to parameter estimation and provide a broader framework of parameter identification for nonlinear models in pharmacology.