ABSTRACT
OBJECTIVE: To determine the effects of a dose of caffeine (2.5 mg/kg, IV) administered to physically fit Thoroughbreds during incremental exercise testing to fatigue on a treadmill. ANIMALS: 10 conditioned Thoroughbreds. PROCEDURE: Horses were randomly assigned to receive caffeine or a control solution. Each horse received both treatments in a crossover design with a 3-week interval between treatments. Each horse was administered caffeine (2.5 mg/kg) or an equivalent amount of a control solution IV. One hour after injection, each horse performed an incremental exercise test to exhaustion. Hematologic values, heart rate, oxygen consumption, carbon dioxide production, plasma lactate concentration, urine and serum concentrations of caffeine and metabolites, and time until exhaustion were monitored. Statistical analysis was performed by use of a mixed-effects linear model. RESULTS: Significant differences in measured values when horses were treated with caffeine or the control solution were not detected. CONCLUSIONS AND CLINICAL RELEVANCE: A dose of caffeine (2.5 mg/kg, IV) appears to have no effect on any performance variable of physically fit Thoroughbreds during incremental exercise testing to fatigue.
Subject(s)
Caffeine/pharmacology , Central Nervous System Stimulants/pharmacology , Horses/physiology , Physical Conditioning, Animal/physiology , Animals , Caffeine/blood , Caffeine/urine , Carbon Dioxide/metabolism , Central Nervous System Stimulants/blood , Central Nervous System Stimulants/urine , Cross-Over Studies , Female , Heart Rate/drug effects , Heart Rate/physiology , Horses/blood , Horses/urine , Lactic Acid/blood , Male , Oxygen Consumption/drug effects , Oxygen Consumption/physiology , Random AllocationABSTRACT
Toxicology studies are typically performed on single compounds, which we hypothesized would miss adverse synergies from chemical mixtures. This hypothesis was tested using an insect repellant and sunscreens because both groups include known permeation enhancers, with prior pediatric reports of toxicity from highly concentrated DEET (N,N-diethyl-m-toluamide). Using real-time mass spectroscopy in a hairless mouse skin model, we confirmed substantial penetration of a 20% DEET standard. Despite a lower (10%) DEET content, a commercially marketed sunscreen formulation had a 6-fold more rapid detection (5 versus 30 min) and 3.4-fold greater penetration at steady state. We also tested the efficacy of DEET microemulsion products and confirmed that one successfully slowed the onset of absorption, but not the steady-state permeation. Risks from mixtures of potential toxins are worthy of routine testing, which can be accomplished by simple assays, and are of utmost importance for pediatric applications.
Subject(s)
DEET/pharmacokinetics , Insect Repellents/pharmacokinetics , Skin/metabolism , Sunscreening Agents/pharmacokinetics , Animals , DEET/analysis , Drug Synergism , In Vitro Techniques , Insect Repellents/analysis , Mice , Mice, Hairless , Skin/drug effects , Skin Absorption/drug effects , Skin Absorption/physiology , Sunscreening Agents/analysisABSTRACT
The objective of this study was to measure and compare the serum concentrations of dexamethasone after oral and transdermal administration using pluronic lecithin organogel in six healthy cats. The study was designed as a crossover, in which the cats were randomly assigned to two groups. The cats received a single dose (0.05 mg kg(-1)) of dexamethasone either orally or transdermally on the inner pinna. Blood samples were taken at 0, 5, 15, 30, 60, 90 and 120 min, and 3, 4, 6, 8, 12 and 24, 48 and 72 h post dexamethasone administration. A mean peak serum concentration of 30.1 ng mL(-1) was detected 15 min after oral administration. Serum concentrations were below detection limits by 24 h. In contrast, there was no significant increase in serum concentrations of dexamethasone after transdermal administration. In cats, transdermal administration of a single dose of dexamethasone did not result in significant serum concentrations compared to oral administration.
Subject(s)
Anti-Inflammatory Agents/pharmacokinetics , Cats/metabolism , Dexamethasone/pharmacology , Administration, Cutaneous , Administration, Oral , Animals , Anti-Inflammatory Agents/administration & dosage , Anti-Inflammatory Agents/blood , Cross-Over Studies , Dexamethasone/administration & dosage , Dexamethasone/blood , Female , Liposomes/administration & dosage , Pilot ProjectsABSTRACT
OBJECTIVE: The serum activity of the hepatic enzyme gamma-glutamyl transferase (GGT) is elevated in the newborn relative to older age groups. Few reports to date have studied the influence of perinatal factors on neonatal serum GGT and no study has assessed the influence of maternal drug ingestion. STUDY DESIGN: Cord blood was randomly collected from 234 liveborn infants and correlated with a range of maternal and fetal perinatal variables to assess influences on cord blood GGT. RESULTS: Our study showed that the range of cord blood GGT activity in 234 randomly selected term newborns was 22 to 556 IU/l. In a subgroup of 75 newborns, GGT activity was independently influenced by only two of the variables studied - cocaine exposure and fetal gender (p=0.009, r=0.39). Females had a lower GGT than males (95+/-66 vs 130+/-90 IU/l, p<0.001) while GGT activity in cocaine-exposed newborns was lower than in cocaine-nonexposed newborns (96+/-48 vs 142+/-109, p<0.01). Birth weight, race, gestational age, and maternal serum GGT were not found to significantly influence cord blood GGT activity. Maternal GGT was uniformly normal and was not affected by any of the variables tested. CONCLUSION: Our findings demonstrate that the reference range for cord blood GGT activity is wide and appears to be influenced by fetal gender and cocaine exposure.
