Search results for "kinetics"
showing 10 items of 2224 documents
Inhibition of molybdenum blue formation by ATP.
1981
Molybdenum blue formation was not affected by the presence of ATP up to a concentration of 1.2 muM/l. At higher concentrations the color development was inhibited relative to ATP concentration, finally reaching complete inhibition. Auto-hydrolysis of ATP was found at a rate of 1.4%/h. An exact determination of inorganic phosphate in the presence of easily hydrolyzed phosphate esters requires the measurement of extinction at fixed time intervals and extrapolation back to time zero.
Psychotropic drug competition for [3H]imipramine binding further indicates the presence of only one high-affinity drug binding site on human α1-acid …
1983
Approaching ‘kit-type’ labelling with 68Ga : the DATA chelators.
2015
The DATA chelators are a novel class of tri-anionic ligands based on 6-amino-1,4-diazepine-triacetic acid, which have been introduced recently for the chelation of (68)Ga. Compared with macrocyclic chelators based on the cyclen scaffold (i.e., DOTA, DO3A, and DO2A derivatives), DATA chelators undergo quantitative radiolabelling more rapidly and under milder conditions. In this study, a systematic evaluation of the labelling of four DATA chelators--DATA(M), DATA(P), DATA(Ph), and DATA(PPh)--with (68)Ga is presented. The results highlight the extraordinary potential of this new class of chelators for application in molecular imaging using (68)Ga positron emission tomography (PET).
Mechanisms of gastroprotection by transdermal nitroglycerin in the rat
1999
Nitric oxide (NO) donors prevent experimentally-induced gastric mucosal damage, but their clinical utility is limited by short duration of action or unsuitability of the pharmaceutical form employed. This study analyses the gastroprotection elicited by a clinically used mode of continuous administration of an NO donor, namely the nitroglycerin patch. Application to rats of a transdermal patch that releases doses of nitroglycerin comparable to those used in man (40, 80, 160 and 400 ng min(-1) rat(-1)) reduced gastric damage induced by indomethacin (25 mg kg(-1), p.o. or s.c.). The nitroglycerin patch (160 ng min(-1) rat(-1)) also diminished damage by oral administration (1 ml) of acidified b…
Kinetics and state-dependent effects of verapamil on cardiac L-type calcium channels.
1996
The voltage dependence and the kinetics of block by verapamil of L-type calcium current (ICa) were investigated in ventricular myocytes from rat hearts using the whole-cell patch-clamp technique. ICa was elicited repetitively in response to depolarizing voltage pulses from -80 mV to 0 mV at different pulse intervals and durations. Verapamil reduced the magnitude of ICa in a frequency-dependent manner without tonic component. The time course of ICa remained unchanged suggesting that not open but inactivated channels were affected by the drug. The interaction of verapamil with inactivated channels was investigated by the application of twin pulses. In the presence of verapamil, the duration o…
Population pharmacokinetic analysis of vancomycin in neonates. A new proposal of initial dosage guideline
2010
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Vancomycin is a glycopeptide antibiotic commonly used to treat resistant gram-positive infections in neonates. While adult dosing guidelines are generally well established, a lack of consensus for optimal dosing regimens in neonates remains. • The large variance in pharmacokinetic values in premature neonates compared with full-term infants is a major barrier to the development of optimal dosing regimens. Pharmacokinetic values have been reported for vancomycin in neonates. However, the studies have included small groups with differing, clinical conditions, serum sampling times and pharmacokinetic models. There are many proposed neonatal dosing gui…
Toxicokinetics of xenobiotics in zebrafish—Comparison between tap and river water
1991
Abstract 1. 1. Uptake and elimination of lindane, 3,4-dichloroaniline, phenol and 4-nitrophenol by the zebrafish Brachydanio rerio were investigated in tap water and in water of the river Rhine. 2. 2. The differences in bioconcentration of chemicals between the two water types did not exceed a factor of 2.5. 3. 3. Elimination kinetics were comparable in tap and river water. 4. 4. It can be concluded that water of the river Rhine does not influence the kinetics of the investigated xenobiotics.
A comparative study of the population pharmacokinetics of gentamicin and amikacin in newborn patients
1993
SUMMARY The population kinetics of gentamicin and amikacin were studied comparatively in newborn patients with a similar range of gestation age (37.9 ± 2.9 and 36.7 ± 3.6 weeks), postnatal age (13.8 ± 7.4 and 16.7 ± 7 days) and weight (2.85 ± 0.57 and 2.72 ± 0.75 kg), undergoing routine therapeutic monitoring of their serum levels. Individual kinetic analysis of serum drug levels was done using a single-compartment model. The population model employed assumes the existence of residual variability in the serum concentrations and interindividual variability in the pharmacokinetic parameters. The clearance and the apparent distribution volume were calculated for each patient using a two-stage …
Opioid metabolism and clinical aspects.
2015
Opioids are are commonly used for the management of acute and chronic pain. Opioids have different physicochemical and pharmacokinetic characteristics, which explain the profound changes in the clinical effect in several clinical conditions. Pharmacokinetics influences the opioid response affecting bioavailability, production of metabolites with residual clinical activity, and elimination. Generality of opioid metabolism and clinical implications for specific opioids in different clinical conditions were reviewed to bridge the gap between pharmacokinetics and clinical response. The knowledge of opioid metabolism is essential, particularly for older and complicated patients who receive multi…