Stability of the ready-to-use solutions of eribulin for intravenous infusion.

A simple HPLC-UV method was developed to determine the stability of ready-to-use eribulin solutions under different storage conditions. The developed method was validated with respect to linearity, accuracy, precision and ruggedness. The following admixtures were prepared: 3-mL polypropylene syringes at concentration of 440 µg/mL and multilayer laminate polyolefin containers containing 0.9% sodium chloride (50 mL) at concentrations of 15.4 and 43.3 µg/mL. The open-vial stability of eribulin was also evaluated. The following storage conditions were tested: 4 °C in the refrigerator; 20 °C under room light exposure; and 20 °C with light-protection. The drug was also subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. The retention time of eribulin was 4.9 min. Admixtures of eribulin solutions in vials, syringes or polyolefin bags at clinically relevant concentrations were physically compatible and chemically stable for at least 14 days at 4 °C in the refrigerator and at 20 °C with or without any protection against light. Degradation was only found to occur under oxidation conditions.

A quantitative liquid chromatography tandem mass spectrometry method for metabolomic analysis of Plasmodium falciparum lipid related metabolites.

Plasmodium falciparum is the causative agent of malaria, a deadly infectious disease for which treatments are scarce and drug-resistant parasites are now increasingly found. A comprehensive method of identifying and quantifying metabolites of this intracellular parasite could expand the arsenal of tools to understand its biology, and be used to develop new treatments against the disease. Here, we present two methods based on liquid chromatography tandem mass spectrometry for reliable measurement of water-soluble metabolites involved in phospholipid biosynthesis, as well as several other metabolites that reflect the metabolic status of the parasite including amino acids, carboxylic acids, energy-related carbohydrates, and nucleotides. A total of 35 compounds was quantified. In the first method, polar compounds were retained by hydrophilic interaction chromatography (amino column) and detected in negative mode using succinic acid-(13)C(4) and fluorovaline as internal standards. In the second method, separations were carried out using reverse phase (C18) ion-pair liquid chromatography, with heptafluorobutyric acid as a volatile ion pairing reagent in positive detection mode, using d(9)-choline and 4-aminobutanol as internal standards. Standard curves were performed in P. falciparum-infected and uninfected red blood cells using standard addition method (r(2)>0.99). The intra- and inter-day accuracy and precision as well as the extraction recovery of each compound were determined. The lower limit of quantitation varied from 50pmol to 100fmol/3×10(7)cells. These methods were validated and successfully applied to determine intracellular concentrations of metabolites from uninfected host RBCs and isolated Plasmodium parasites.

Stability of ready-to-use temsirolimus infusion solution (100mg/L) in polypropylene containers under different storage conditions.

The aim of this study was to determine the stability of ready-to-use temsirolimus infusion solutions under different storage conditions. Solutions were prepared in polypropylene containers by adding temsirolimus injection to 0.9% sodium chloride infusion to reach a final concentration of 100mg/L. The following storage conditions were tested: (i) 4(o)C in the refrigerator; (ii) 20(o)C under room light exposure and light protection; and (iii) outdoor temperature with sunlight exposure. Moreover, stress testing was performed on drug substance at 20(o)C under ultraviolet (UV) radiation (365 nm). A stability-indicating high-performance liquid chromatography (HPLC) method with UV detection was developed for this analysis. Precision was below 4% and accuracy ranged from 97 to 102%. The lower limit of quantitation was 0.1mg/L. The degradation products produced after UV light exposure were detected upon further analysis by mass spectrometry detection. The stability of temsirolimus is light and temperature dependent. After storage at 20(o)C with room light exposure, the rate of degradation was around 0.25%/h; after 1 day, 92.5% of the initial temsirolimus concentration was recovered. When protected from light, at 4 and 20(o)C, losses were decelerated; the decrease in drug concentration was 1.0 and 1.56% per day, respectively. Under daylight exposure, a substantial decrease in drug concentration was observed; after 1h, losses were higher than 10%. Exposed to UV light, half of the drug was lost after 45 min. In conclusion, temsirolimus 100mg/L in infusion polypropylene bags containing 0.9% sodium chloride was chemically stable when protected from light for 4 and 3 days at 4 and 20(o)C, respectively.

Methotrexate pharmacokinetics in childhood acute lymphoblastic leukaemia: a prognostic value?

WHAT IS KNOWN AND OBJECTIVE: In industrialized countries, acute lymphoblastic leukaemia (ALL) is the most frequent cancer in children aged less than 15 years. High-dose methotrexate is a common component of many chemotherapeutic protocols for childhood with ALL. Our objective was to retrospectively evaluate the pharmacokinetics and plasma levels of high-dose methotrexate as it relates to event-free survival (EFS) in children with ALL. METHODS: Relapsed patients and subjects in EFS were compared for MTX serum concentrations 24, 36, 48 and 72 h after the start of 24 h infusion. Clearance (Cl), area under the curve (AUC) and volume of distribution (V(d) ) of the drug were estimated by the NONMEM computer program and also compared between both groups. RESULTS AND DISCUSSION: Among 69 children included, 54 (78·3%) were still in EFS, whereas 15 (21·7%) relapsed. The difference between relapsed and EFS patients for the pharmacokinetic parameters studied was not significant. On the contrary, the cohort studied was representative and known prognostic factors for relapse in ALL were significantly associated with relapse. WHAT IS NEW AND CONCLUSION: Serum concentrations and pharmacokinetic parameters of MTX are not associated with outcome in ALL. Prognoses based on single-drug pharmacokinetic estimates within a complex multiple-agent protocol appear to be unreliable. However, therapeutic drug monitoring of high-dose methotrexate remains a useful tool for early detection of impaired elimination and for avoiding systemic toxicity.

Population pharmacokinetics of nalbuphine after surgery in children.

BACKGROUND: Nalbuphine is an opioid analgesic agent widely used for control of mild-to-severe pain. However, limited data are available on the pharmacokinetics of this drug in children. The aim of this study was to characterize the population pharmacokinetics of nalbuphine in patients with ages ranging from 1 to 11 yr and to identify patient characteristics partially explaining inter-individual variability in nalbuphine pharmacokinetic parameters. METHODS: Twenty-two children were included in this study. They received nalbuphine after surgery by continuous infusion (loading dose, 0.2 mg kg(-1) over 10 min followed by continuous infusion of 0.8 mg kg(-1) over 24 h). If pain relief was not adequate, 0.1 mg kg(-1) bolus doses were allowed in 10 min. Eleven blood samples were collected per patient. The data were analysed by non-linear mixed-effect modelling with the use of a two-compartment structural model. RESULTS: Twenty patients completed the study. In the final model, the parameter values were standardized for a body weight of 70 kg using an allometric model. Population parameter estimates were: clearance 130 litre h(-1) 70 kg(-1), inter-compartment clearance 75.6 litre h(-1) 70 kg(-1), central volume of distribution 210 litre 70 kg(-1), and peripheral volume of distribution 151 litre 70 kg(-1). In the children of this study, total clearance expressed in litre h(-1) kg(-1) decreased significantly with increasing age and the elimination half-life significantly increased. CONCLUSIONS: The allometric power model developed in this study best reflected the data and may be useful for dose adjustment.

Clinical impact of intesified 5-Fluorouracil-based chemotherapy using a prospective pharmacokinetically-guided dosing approach: comparative study in elderly and non-elderly patients with metastatic colorectal cancer.

We compared clinical outcome and pharmacokinetic (pK) parameters of a new pharmacokinetically-guided dosing strategy in two groups of patients (age < or >65 years) with metastatic colorectal cancer (mCRC). We retrospectively analyzed all the patients with mCRC, receiving standard LV5FU2 regimen during cycle-1, intensified from cycle-2 onwards according to an adaptation schedule based on the area under the concentration-time curve (AUC) value (mg.h/l.m(2)) of 5-FU measured during cycle-1. Among the 103 eligible patients, the 48 elderly (median age 70 range 65-80) did not differ significantly from the 55 non-elderly patients (median age 59 range 33-64) in pPK parameters (including AUC at cycle-1 and cycle-2), efficacy (objective response rate of 27% [16.1-40.9] in younger and 35% [22.2-50.5] in older patients, p = 0.4) and tolerability (33.3% of overall grade 3-4 toxicities in older patients and 34.5% in younger, p = 0.9). Our data indicated high dose-intensity values, not significantly different between elderly and non-elderly patients. it was feasible to increase the 5-fU continuous infusion dose in 43/55 (78%) younger and 40/48 (83%) older patients (p=0.509) and even to double it in half of the patients of both groups. Aging did not seem to limit intensified chemotherapy or to affect the pK behavior of the 5-FU.

Rapid resolution liquid chromatography-mass spectrometry determination of SAR97276 in monkey matrices. Pharmacokinetics in rhesus monkey infected by Plasmodium cynomolgi.

Since several years, we developed a new class of antimalarial drugs targeting the phospholipid metabolism of the Plasmodium falciparum malaria parasite. The bis-thiazolium compound, SAR97276, is the lead compound and is now in clinical development. In this paper, we applied the fast rapid resolution liquid chromatography-mass spectrometry technique to the analysis of SAR97276 in monkey matrices. The sample pre-treatment procedure involved an acidic precipitation of proteins followed by solid-phase extraction. The monocationic compound, T2, was used as internal standard. A good separation was achieved on a Zorbax eclipse XDB C8 column (1.8 microm, 50 mm x 4.6mm) with a mobile phase consisting of acetonitrile-trimethylamine-formate buffer (pH 3) gradient elution. The total run time was 8 min. Inter-assay precisions were <10% in plasma, and 85% in plasma, and >75% in blood. The lower limits of quantitation were 3.3 microg/l in plasma and 3.3 microg/kg in blood. No matrix effect was observed. This newly developed method is sensitive, selective, reproducible, and stability indicating. It was used to analyse samples taken during a pharmacokinetic/pharmacodynamic study carried out in infected Rhesus monkey by Plasmodium cynomolgi as part of the ongoing development of SAR97276.

Population pharmacokinetics of the two enantiomers of tramadol and O-demethyl tramadol after surgery in children.

BACKGROUND: Few data are available on the stereoselective pharmacokinetics of tramadol in children. The aim of this study was to develop a population pharmacokinetic model for the (+)- and (-)-enantiomers of tramadol and its O-demethyl tramadol metabolite (M1) in children. METHODS: Twenty-five children (1-8 yr) were included in this study. Tramadol was administered after surgery by continuous infusion (loading dose, 2 mg kg(-1) i.v. over 10 min followed by continuous infusion of 8 mg kg(-1) over 24 h). If pain relief was inadequate, additional 1 mg kg(-1) i.v. bolus doses of tramadol were given over 10 min. A two-compartment structural model was used with NONMEM. RESULTS: For both enantiomers of tramadol, weight was the only patient characteristic parameter showing significant covariate effects on clearance (CL). CL increased by 5.7-6.1 litre h(-1) between 8-12 and 13-16 kg, and by 2.4-3.3 litre h(-1) between 13-16 and 17-33 kg. The rate constants associated with the metabolite elimination [0.144 h(-1), (+)-M1 and 0.18 h(-1), (-)-M1] were smaller than the elimination rate constants of the parent drugs [0.243 h(-1), (+)-tramadol and 0.241 h(-1), (-)-tramadol], suggesting that the metabolite disposition was rate-limited by its elimination. The presence of two subpopulations of patients was suspected on the basis of the observed bimodal distributions of the AUC(M1)/AUC(tramadol) ratios. CONCLUSIONS: The results of this study combine relationships between tramadol CL and patient covariates that may be useful for dose adjustment. Polymorphism is likely to contribute to the interpatient variability observed in the AUC M1/AUC tramadol ratios.

A liquid chromatography-mass spectrometry assay for simultaneous determination of two antimalarial thiazolium compounds in human and rat matrices.

A new class of antimalarial drugs targeting phospholipid metabolism of the malarial parasite is now in development. In the strategy of this development, two mono-thiazolium salts, T1 and T2, need to be monitored. A liquid chromatography-mass spectrometry (LC-MS) method has been developed and validated according to FDA guidelines for simultaneous determination of T1 and T2 in plasma, whole blood and red blood cells (RBCs) from human and rat. The sample-pre-treatment procedure involved solid phase extraction after protein precipitation. Chromatography was carried out on a Zorbax eclipse XDB C8 column and mass spectrometric analysis was performed using an Agilent 1,100 quadrupole mass spectrometer working with an electrospray ionization source. LC-MS data were acquired in single ion monitoring mode at m/z 312, 326 and 227 for T1, T2 and the internal standard (T3), respectively. The drug/internal standard peak area ratios were linked via a quadratic relationship to concentrations (human and rat plasma: 2.25-900 microg/l; human blood and rat RBCs: 4.5-900 microg/kg). Precision was below 14.5% for T1 and below 13% for T2. Accuracy was 92.6-111% for T1 and 95.6-108% for T2. Extraction recoveries were >or=85% in plasma and >or=53% in blood and RBCs. For T1 and T2, the lower limits of quantitation were 2.25 microg/l in plasma, and 4.5 microg/kg in whole blood and RBCs. Stability tests under various conditions were also investigated. This highly specific and sensitive method was useful to analyse samples from pharmacokinetic studies carried out in rat and would also be useful in clinical trials at a later stage.

Ibogaine, an anti-addictive drug: pharmacology and time to go further in development. A narrative review.

Ibogaine is an indole alkaloid derived from the bark of the root of the African shrub Tabernanthe iboga. Psychoactive properties of ibogaine have been known for decades. More recently, based on experimental data from animals and anectodal reports in human, it has been found that this drug has anti-addictive effects. Several patents were published between 1969 and 1995. The pharmacology of ibogaine is quite complex, affecting many different neurotransmitter systems simultaneously. However, the pharmacological targets underlying the physiological and psychological actions of ibogaine are not completely understood. Ibogaine is rapidly metabolized in the body in noribogaine. The purpose of this article was to review data from the literature concerning physicochemical properties, bio-analytical methods, and pharmacology of ibogaine; this article will be focused on the use of this drug as anti-addictive agent.

Quantitative analysis of a bis-thiazolium antimalarial compound, SAR97276, in mouse plasma and red blood cell samples, using liquid chromatography mass spectrometry.

A sensitive and selective liquid chromatography-mass spectrometry (LC-MS) method has been developed for the determination of a new antimalarial bisthiazolium salt, SAR97276, in mouse plasma and red blood cells (RBCs). A drug of the same chemical series as the test drug, T2, was used as internal standard. The method involved solid phase extraction of the compound and the internal standard from the two matrices using Oasis HLB columns. LC separation was performed on a Zorbax eclipse XDB C8 column (5 microm) with a mobile phase of acetonitrile containing trimethylamine (130 microl/l, solvent A) and 2 mM ammonium formate buffer (solvent B). MS data were acquired in single ion monitoring mode at m/z 227 for SAR97276 and m/z 326 for T2. The matrix had no influence on the detection of either SAR97276 or T2. The drug/internal standard peak area ratios were linked via quadratic relationships to plasma (1.65-1322 ng/ml) and RBC concentrations (3.31-2644 ng/ml). Precision was below 14% and accuracy was 91.4-104%. Dilution of the samples had no influence on the performance of the method. Extraction recoveries of SAR97276 were > or =90% in plasma and > or =60% in RBCs. The lower limits of quantitation were 1.65 ng/ml in plasma and 3.31 ng/ml in RBCs. Stability tests under various conditions were also investigated. The method was successfully used to determine the pharmacokinetic profile of SAR97276 in healthy mouse.

Stability of amphotericin B and nystatin in antifungal mouthrinses containing sodium hydrogen carbonate.

Amphotericin B and nystatin are two polyene antibiotics that are potent antifungal agents. These drugs are active against most pathogenic fungi like Aspergillus and Candida. Mouthrinses containing these drugs are used for preventive and curative treatment of fungal infections like oral candidiasis, which can cause multiple diseases in cancer patients. Because there were no marketed antifungal mouthrinses available, their preparations were performed at the hospital and town pharmacies. To date, there are no data available on the stability of both these drugs in the form of mouthrinses. Therefore, each mouthrinse had to be prepared extemporaneously. The aim of this study was to investigate the stability of amphotericin B (Fungizone) and nystatin (Mycostatine) in the form of mouthrinses containing 1.4% sodium hydrogen carbonate. The stability of these solutions was tested at different temperatures (4-37 degrees C) with or without electric- or sunlight exposure and in two types of containers (glass and polypropylene) over a 15-day period. The admixtures were also monitored for colour change and pH. Amphotericin B and nystatin were quantified by high-performance liquid chromatography. At 4 degrees C, amphotericin B and nystatin were stable for 15 days in polypropylene. When stored in polypropylene at room temperature, with or without light protection, amphotericin B and nystatin were stable for 3 and 4 days, respectively.

Population pharmacokinetics of mycophenolic acid in kidney transplant pediatric and adolescent patients.

Current data on mycophenolate mofetil (MMF) suggest that there is a pharmacokinetic/pharmacodynamic relationship between the mycophenolic acid (MPA) area under the curve (AUC) during treatment and both the risk of acute rejection and the occurrence of side effects. The aim of this study was to characterize the population pharmacokinetics of MPA in kidney transplant patients between the ages of 2 and 21 years and to propose a limited sampling strategy to estimate individual MPA AUCs. Forty-one patients received long-term oral MMF continuous therapy as part of a triple immunosuppressive regimen, which also included cyclosporine or tacrolimus (n=3) and corticosteroids. Therapy was initiated at a dose of 600 mg/m twice daily. The population parameters were calculated from an initial group of 32 patients. The data were analyzed by nonlinear mixed-effect modeling using a 2-compartment structural model with first-order absorption and a lag time. The interindividual variability in the initial volume of distribution was partially explained by the fact that this parameter was weight-dependent. Fifteen concentration-time profiles from 13 patients were used to evaluate the predictive performance of the Bayesian approach and to devise a limited sampling strategy. The protocol, involving two sampling times, 1 and 4 hours after oral administration, allows the precise and accurate determination of MPA AUCs (bias -0.9 microg.h/mL; precision 6.02 microg.h/mL). The results of this study combine the relationships between the pharmacokinetic parameters of MPA and patient covariates, which may be useful for dose adjustment, with a convenient sampling procedure that may aid in optimizing pediatric patient care.

Simultaneous determination of dexamethasone and 6 beta-hydroxydexamethasone in urine using solid-phase extraction and liquid chromatography: applications to in vivo measurement of cytochrome P450 3A4 activity.

It has been demonstrated that the formation of the hydrophilic metabolites of dexamethasone, 6 alpha- and 6 beta-hydroxydexamethasone, correlated with cytochrome P450 (CYP) 3A4 enzyme levels. So, the 6 beta-hydroxydexamethasone/dexamethasone urinary ratio could be a specific marker for human CYP3A4 activity. We have developed a sensitive and specific high-performance liquid chromatographic method for the simultaneous quantification of urinary free dexamethasone and 6 beta-hydroxydexamethasone using 6 alpha-methylprednisolone as internal standard. This method involved a solid phase extraction of the three compounds from urine using Oasis HLB Waters cartridges with an elution solvent of ethyl acetate (2 ml) followed by diethyl ether (1 ml). Separation of the three analytes was achieved within 24 min using a reversed-phase Nova-Pak C(18) analytical column (4 microm, 300 mm x 3.9 mm i.d.). An ultraviolet detector operated at 245 nm was used with a linear response observed from 10 to 100 ng/ml for dexamethasone and from 25 to 1000 ng/ml for 6 beta-hydroxydexamethasone. Obtained from the method validation, inter-assay precision was below 15% and accuracy ranged from 95.7 to 110%. The extraction efficiency of the assay was approximately of 99% and was constant across the calibration range. The lower limit of quantitation was 10 ng/ml for dexamethasone and 25 ng/ml for 6 beta-hydroxydexamethasone; at these levels, precision was below 16% and accuracy was 99-109%. This method was applied to in vivo measure of the CYP3A4 activity.

Population pharmacokinetics of ciprofloxacin in pediatric and adolescent patients with acute infections.

The aim of the present study was to characterize the population pharmacokinetics of ciprofloxacin in patients with and without cystic fibrosis ranging in age from 1 day to 24 years and to propose a limited sampling strategy to estimate individual pharmacokinetic parameters. Patients were divided into four groups according to the treatment schedule. They received ciprofloxacin by intravenous infusion (30 min) or by the oral route. The number of samples collected from each patient ranged from 1 to 12. The population parameters were computed for an initial group of 37 patients. The data were analyzed by nonlinear mixed-effect modeling by use of a two-compartment structural model. The interindividual variability in clearance (CL) was partially explained by a dependence on age and the patient's clinical status. In addition, a significant relationship was found between weight and the initial volume of distribution. Eighteen additional patients were used for model validation and evaluation of limited sampling strategies. When ciprofloxacin was administered intravenously, sampling at a single point (12 h after the start of infusion) allowed the precise and accurate estimation of CL and the elimination half-life, as well as the ciprofloxacin concentration at the end of the infusion. It should be noted that to take into account the presence of a lag time after oral administration, a schedule based on two sampling times of 1 and 12 h is needed. The results of this study combine relationships between ciprofloxacin pharmacokinetic parameters and patient covariates that may be useful for dose adjustment and a convenient sampling procedure that can be used for further studies.

Pharmacokinetic-pharmacodynamic modelling of recombinant human erythropoietin in athletes.

The aim of this study was to develop a pharmacokinetic model that takes into account the negative feedback loop of endogenous erythropoietin production observed after repeated recombinant human erythropoietin administration. A pharmacodynamic data analysis was performed using the changes in i) reticulocyte count, ii) serum levels of soluble transferrin receptors, and iii) soluble transferrin receptors/serum proteins ratio as an index of the therapeutic effect of the hormone. Nine athletes were included in the study; they received repeated subcutaneous administrations (50 IU x kg(-1) per day) of recombinant human erythropoietin. The mean half-life of the terminal part of the curve was 35.5 h, and the total clearance was 17 ml x h(-1) x kg(-1). The total clearance was about two times higher in athletes than in untrained subjects (5.5 - 7.5 ml x h(-1) x kg(-1)) and the half-life period of plasma erythropoietin after subcutaneous administration was five times longer compared to intravenous administration (4 to 7 h). Thus, after subcutaneous administration, the terminal part of the curve should correspond to the absorption phase, instead of to the elimination phase (flip-flop phenomenon). The pharmacodynamic relationship based on a sigmoid Emax model can be reasonably used to relate the changes observed in the markers to recombinant human erythropoietin administration. Recombinant human erythropoietin induces a delayed increase in reticulocytosis and in soluble transferrin receptor levels. In comparison with baseline, the increase of these markers became significant from the third and the tenth day after the initial administration of the hormone, respectively. These results were in accordance with the equilibration delay computed from the pharmacokinetic-pharmacodynamic data modelling (half-life of 25.7 h and 10 days, respectively). The recombinant hormone was well tolerated during this study.

Is whole body impedance a predictor of blood viscosity?

Bioelectrical impedancemetry (BIA) has received a widespread interest as a non-invasive approach to body fluid volumes. Since similar techniques have been studied to assess in vitro rheological properties of blood, we investigated the relationships between whole body impedance and blood viscosity parameters in order to determine possible predictive equations. 30 sportsmen (24.6+/-1.01 years; 73.96+/-1.62 kg; 177.73+/-1.33 cm) were enrolled into the study. Body composition was assessed with a multifrequency bioelectrical impedancemeter (Dietosystem Human IM Scan) using low intensity at the following frequencies: 1, 5, 10, 50 and 100 kHz. Viscometric measurements were done at 1000 s(-1) with a falling ball viscometer (MT 90 Medicatest). Hematocrit (Hct) was measured with microcentrifuge. A standardized exercise test was performed on a cycloergometer during 25 minutes. Physical working capacity (W170) was calculated and VO2max was evaluated with Astrand nomograms. Two hemorheological parameters were independently correlated with impedance (Z) measurements: whole blood viscosity (WBV) at 100 kHz (r=0.518; p=0.01) and Hct at 1 kHz (r=-0.485; p=0.01). Plasma viscosity was correlated multilinearly with water/fat free mass and Z at 10 kHz (r=0.441; p=0.02). In addition both WBV and Z at 100 kHz exhibited correlations with aerobic working capacity (VO2max ) with r=-0.482 and r=-0.475 (p

Reduction of red blood cell disaggregability during submaximal exercise: relationship with fibrinogen levels.

Effects of exercise on erythrocyte aggregation were investigated in 19 elite athletes. High shear rate viscometry (1000 s(-1) evidenced an increase in blood viscosity explained by an increase in hematocrit (+8% p<0.01) and plasma viscosity (+7% p<0.01). Erythrocyte rigidity index and erythrocyte aggregability measured using the Myrenne erythroaggregometer did not change. However, using the laser backscattering technique (SEFAM erythroaggregometer), we observed significant changes in aggregability and desaggregability after 25 min of exercise. The initial aggregation time (TA) decreased by 33% (p<0.01), while the final aggregation time decreased by 13.6% (p<0.01). TA was correlated with aerobic working capacity (r=0.73; p=0.005), which was negatively correlated with blood viscosity at rest (r=-0.57; p=0.043). A significant relationship was observed between TA and the initial fibrinogen levels (r=0.71; p<0.01). The plasma volume contraction during exercise was found to be statistically explained by the water loss proportional to the total work load. Thus, laser backscattering demonstrates an increase in aggregability and a decrease in disaggregability of red cells during exercise, proportional to baseline fibrinogen values.

Is the feeling of heavy legs in overtrained athletes related to impaired hemorheology?

The feeling of having "heavy legs" (FHL) is commonly reported in the overtraining syndrome (OTS), i.e., the condition wherein an athlete is training excessively, yet performance deteriorates. Since FHL is also a sign of chronic venous insufficiency where it can be corrected by rheo-active drugs, and given the fact that OTS is also a hemorheologic disease associated with mild hemoconcentration, we investigated whether the FHL is associated with a hemorheologic profile. 37 athletes training 13.05+/-0.97 hr/week completed the French questionnaire of Overtraining (mean score: 11.66+/-1.96) and underwent a medical check-up including hemorheological measurements. 14 subjects quote the item: "I have the FHL". Although well matched with the 23 others for age and body composition, FHL subjects had higher plasma viscosity (1.44+/-0.05 vs 1.32+/-0.02 mPa.s; p<0.05) and a higher red cell aggregation as measured with laser backscattering (Affibio indices: final aggregation time "TF": 36.77+/-1.88 vs 44.26+/-2.37; p<0.05; aggregation index at 10 s "S10": 26.31+/-1.14 vs 21.92+/-1.19; p<0.05). The OTS score was correlated positively with plasma viscosity (r=0.549; p=0.008), whole blood viscosity (r=0.4458; p=0.03), and the following aggregability parameters: "S10" (r=0.4818; p=0.0232) and the aggregation index at 60 s "S60" (r=0.4601; p=0.0312). The OTS score was also correlated negatively with the aggregability parameters "TF" (r=-0.4432; p=0.0389) and the initial aggregation time "TA" (exponential relationship r=-0.458; p=0.03). These findings suggest that the feeling of heavy legs in overtrained athletes is related to OTS-related hemorheologic disturbances, namely mild plasma hyperviscosity and mild erythrocyte hyperaggregability.

Hemorheological correlates of fitness and unfitness in athletes: moving beyond the apparent "paradox of hematocrit"?

UNLABELLED: Negative correlations between blood viscosity parameters and fitness have been reported, but their physiological meaning remains incompletely understood. Since rheo-active treatments are used in athletes doping, we aimed at clarifying the relationships between hematocrit (Hct), viscosity and performance by comparing aerobic capacity, overtraining questionnaire, and hemorheological parameters. SUBJECTS AND METHODS: 29 sportsmen (24.71+/-1.05 yr; 74.90+/-1.44 kg; 178.5+/-1.05 cm) underwent a standardised exercise test. Physical working capacity (W170), maximal power output (Wmax) and maximal oxygen consumption (VO2max ) were calculated. Viscometric measurements were done with a MT 90 Medicatest viscosimeter. Hct was measured with microcentrifuge. All subjects answered the overtraining questionnaire proposed by the French Society for Sports Medicine. RESULTS: The best correlate of maximal power output (Wmax) was whole blood viscosity (r=-0.383, p<0.001). The stepwise regression analysis only selected Hct as W170 determinant (r=-0.66, p<0.001). Similarly the best determinant of VO2max, expressed as a percentage of theoretical values, was Hct (r=-0.462, p=0.01). Hct/viscosity ratio (Hct/eta), a proposed index of Hct's positive influence on O2 transfer to tissues, was positively correlated to Wmax expressed as a percentage of theoretical values (r=0.487, p=0.02). The overtraining score was correlated to plasma viscosity (r=0.450, p=0.016). CONCLUSION: The best hemorheogical correlate of fitness is a low hematocrit and the best hemorheological correlate of overtraining is increased plasma viscosity.