Acute effect of different normobaric hypoxic conditions on shuttle repeated sprint performance in futsal players

This study aimed to investigate the acute effects of different environmental oxygen conditions on shuttle repeated sprint performance in futsal players. Using a counterbalanced design, 16 male university-level futsal players performed 3 sets of shuttle repeated sprints (6 × 10 s) over a 5m distance with 20 s active rest between reps and 5 min active rest between sets. Participants completed 4 trials in a random order over 4 weeks with different inspired oxygen fractions for each trial (FIO2 = 20.9%, 14.5%, 13.5% and 12.5%). Electromyography (RMSEMG) data was recorded from the vastus lateralis muscle during sprinting. The number of completed shuttles in each 10 s period, blood lactate concentration, rating of perceived exertion, oxygen saturation (SpO2), and cardiorespiratory variables were recorded after each set. We found that after set3, blood lactate concentration was substantially higher (p <0.05) in the 12.5% FIO2 (10.4 ± 2.1 mmol/L) compared to normoxia, 14.5% or 13.5% condition (5.0 ± 1.6, 7.8 ± 1.5, and 9.4 ± 1.9 mmol/L, respectively). Compared to normoxia, the RMSEMG signal was 34.1% lower in the 12.5% condition, 14.1% and 18.6% lower in the 14.5% and 13.5% oxygen condition respectively. Moreover, SpO2 after set3 was substantially lower (p <0.05) in 12.5% (73.7 ± 3.4%) compared to normoxia, 14.5% or 13.5% condition (95.1 ± 1.8, 81.1 ± 2.1, and 79.1 ± 2.4%, respectively). Overall the lower FIO2 conditions produced lower in number of sprints, and highest heart rate, ventilation and rating of perceived exertion levels. In conclusion, FIO2 13.5% is an appropriate choice for shuttle repeated sprint training in hypoxia. Although, FIO2 13.5% was lower in benefitcial responses than FIO2 12.5% but FIO2 12.5% might produce unnecessary and unwanted fatigue from insufficient oxygen to athletes

Dose-escalating study of the safety and pharmacokinetics of nelfinavir in HIV-exposed neonates

The pharmacokinetics of nelfinavir (NFV) in neonates younger than 4 weeks of age was assessed. Three cohorts of HIV-exposed neonates were enrolled in cohorts to receive 15, 30, and 45 mg of NFV/kg twice daily in combination with stavudine and didanosine for 4 weeks after birth. Trough NFV concentrations (C(min)) were measured at 1 and 7 days of age. Intensive pharmacokinetic evaluations were performed at 14 and 28 days of age. The median NFV C(min) values in the 15 mg/kg (6 patients), 30 mg/kg (5), and 45 mg/kg (11) cohorts at 1, 7, 14, and 28 days of age were 0.19, 1.21, 0.51, and 0.33; 1.02, 3.18, 0.73, and 0.55; and 0.67, 3.21, 0.70, and 0.73 mg/L, respectively. The median area under the plasma concentration-versus-time curve values over 12 hours in the three cohorts at 14 and 28 days of age were 14.4 and 8.7, 19.4 and 15.8, and 23.4 and 18.5 (h. mg)/L, respectively. No serious adverse events were observed. In conclusion, the systemic exposure of NFV decreased after 7 days of age, possibly because of hepatic enzyme maturation, autoinduction of NFV metabolism, and/or changes in NFV absorption. The highly variable systemic exposure observed in the study indicates that therapeutic drug monitoring seems warranted to ensure adequate NFV dosing in this populatio

Pharmacokinetics of Stavudine and Didanosine Coadministered with Nelfinavir in Human Immunodeficiency Virus-Exposed Neonates

We evaluated the pharmacokinetics of stavudine (d4T) and didanosine (ddI) in neonates. Eight neonates born to human immunodeficiency virus-infected mothers were enrolled to receive 1 mg of d4T per kg of body weight twice daily and 100 mg of ddI per m(2) once daily in combination with nelfinavir for 4 weeks after birth. Pharmacokinetic evaluations were performed at 14 and 28 days of age. For d4T, on days 14 and 28, the median areas under the concentration-time curves from 0 to 12 h (AUC(0–12)s) were 1,866 and 1,603, ng · h/ml, respectively, and the median peak concentrations (C(max)s) were 463 and 507 ng/ml, respectively. For ddI, on days 14 and 28, the median AUC(0–10)s were 1,573 and 1,562 h · ng/ml, respectively, and the median C(max)s were 627 and 687 ng/ml, respectively. Systemic levels of exposure to d4T were comparable to those seen in children, suggesting that the pediatric dose of 1 mg/kg twice daily is appropriate for neonates at 2 to 4 weeks of age. Levels of exposure to ddI were modestly higher than those seen in children. Whether this observation warrants a reduction of the ddI dose in neonates is unclear