Search results for "kinetics"

Impact of nutritional status on the pharmacokinetics of erlotinib in rats

2015

Malnourishment is a complex condition in which physiopathological changes take place in multiple systems as a result of energy, protein and nutrient deficiency. The purpose of this study was to evaluate, using an experimental animal model, the impact of nutritional status on the pharmacokinetic profile of erlotinib, a reversible, highly selective, human epidermal growth factor receptor (HER1/EGFR) tyrosine kinase inhibitor. Two groups of rats -WN (well-nourished) and UN (undernourished) - were fed with different diets for 23-26 days. Rats were assigned randomly to one of three erlotinib treatments (n = 42) consisting of a single dose administered intravenously (i.v.), via oral solution or v…

Dexlansoprazole Delayed Release: Pharmacotherapy of Erosive Esophagitis and GERD

2011

Dexlansoprazole MR is a modified release formulation of the R-enantiomer of lansoprazole, which employs a novel Dual Delayed Release (DDR) technology. Pharmacokinetic studies have shown that the DDR technology provides a two peaks drug release, accuring 1–2 hours and 4–5 hours after dosing, leading to an extended duration of therapeutic plasma drug concentrations compared with conventional delayed release lansoprazole. Dexlansoprazole MR 30 and 60 mg provided superior intragastric pH control compared to that obtained with lansoprazole 15 mg and 30 mg once daily dosing. Dexlansoprazole can be taken without regard to food. The drug has been shown to be as efficacious as lansoprazole in heali…

Nigral control of hippocampal epilepsy: a dopaminergic hypothesis

1988

Oxygen exchange in the erythrocyte

1969

Es wird eine Ubersicht uber die mathematischen und experimentellen Aspekte des O2-Austausches im Erythrozyten gegeben. Der Gesamtprozess kann als eine Sauerstoffdiffusion mit gekoppelter Hamoglobin-Sauerstoff-Reaktion beschrieben werden. Fur die mathematische Analyse muss also die partielle Differentialgleichung der Diffusion durch ein Gleichungssystem erweitert werden, das dem chemischen Reaktionsablauf Rechnung tragt. Voraussetzung hierfur ist die Aufstellung eines Modells zur molekularen Interpretation der O2-Bindungskurve. Die vereinfachten Differentialgleichungen fur Diffusion und Reaktion lassen sich unter Beachtung der Rand- und Anfangsbedingungen nur naherungsweise integrieren.

Genetics of the variable expression of CYP3A in humans.

2004

CYP3A isozymes participate in the metabolism of 45-60% of currently used drugs and of a variety of other compounds such as steroid hormones, toxins, and carcinogens. The CYP3A expression status is a major determinant of drug efficacy and safety, and it may also affect an individual's predisposition to certain cancers. The inter- and intraindividual expression of CYP3A is variable because of a complex interplay between genetic and environmental factors. Markers predictive of the individual CYP3A activity could improve therapies with CYP3A substrates by personalised dose adjustments, but their development has been slower than for other drug-metabolizing enzymes. Here we summarize the recent p…

Modulation of the pharmacokinetics, therapeutic and adverse effects of NSAIDs by Chinese herbal medicines.

2014

Concomitant use of NSAIDs and Chinese herbal medicines (CHMs) is frequent, yet summarized information on their interactions is lacking.A systematic review of literature in four evidence-based English databases was performed. Articles which reported CHMs altering the pharmacokinetics, therapeutic and adverse effects of NSAIDs were identified and summarized. Such interactions may lead to beneficial, detrimental or no change in outcomes. The current review covers four therapeutic effects of NSAIDs, including: i) anti-inflammatory; ii) analgesic; iii) antiplatelet, cardiovascular and cerebrovascular; and iv) anticancer effects and four adverse effects of NSAIDs, including: i) gastrointestinal u…

CYP3A5*3 and CYP2C8*3 variants influence exposure and clinical outcomes of tacrolimus-based therapy

2020

Aim: The influence of variants in pharmacokinetics-related genes on long-term exposure to tacrolimus (TAC)-based therapy and clinical outcomes was investigated. Patients & methods: Brazilian kidney recipients were treated with TAC combined with everolimus (n = 178) or mycophenolate sodium (n = 97). The variants in CYP2C8, CYP2J2, CYP3A4, CYP3A5, POR, ABCB1, ABCC2, ABCG2, SLCO1B1 and SLCO2B1 were analyzed. Main results: CYP3A5*3/*3 genotype influenced increase in TAC concentration from week 1 to month 6 post-transplantation (p < 0.05). The living donor and CYP2C8*3 variant were associated with reduced risk for delayed graft function (OR = 0.07; 95% CI = 0.03–0.18 and OR = 0.45; 95% C…

Nonlinear intestinal absorption kinetics of cefuroxime axetil in rats.

1997

Cefuroxime is commercially available for parenteral administration as a sodium salt and for oral administration as cefuroxime axetil, the 1-(acetoxy)ethyl ester of the drug. Cefuroxime axetil is a prodrug of cefuroxime and has little, if any, antibacterial activity until hydrolyzed in vivo to cefuroxime. In this study, the absorption of cefuroxime axetil in the small intestines of anesthetized rats was investigated in situ, by perfusion at four concentrations (11.8, 5, 118 and 200 microM). Oral absorption of cefuroxime axetil can apparently be described as a specialized transport mechanism which obeys Michaelis-Menten kinetics. Parameters characterizing absorption of prodrug in free solutio…

Evidence of a flip-flop phenomenon in acamprosate pharmacokinetics: an in vivo study in rats.

2006

The pharmacokinetics of acamprosate were examined in the rat after oral and intravenous administration in order to detect the possible presence of a flip-flop phenomenon. Rats received 9.3 or 73.3 mg/kg of the drug as an intravenous bolus. The same doses were orally administered via gastric intubation. Plasma samples were taken from the jugular vein for determination of acamprosate concentration by liquid scintillation counting. The drug content was also quantified in urine and faeces. The acamprosate bioavailability was close to 20%, the amount recovered in the faeces being around 80% of the administered dose. The terminal slope of the oral plasma curve was significantly lower than that ob…

Quantitative in vivo microdialysis in pharmacokinetic studies: some reminders.

2005

This paper reviews the empirical methods of quantitative microdialysis that have been used to interpret the results obtained from pharmacokinetic studies. The concept of extraction efficiency or recovery and the properties of recovery in vivo (variation with flow rate, time dependency and influence of the mode of administration) are considered. The most frequently used methods for determining recovery in vivo are described and evaluated in the light of recent theoretical studies. Specifically, we review the variation of flow rate method, the very slow flow method, the no net flux method and the delivery and retrodialysis methods. Special emphasis is placed on the description of each method,…