scholarly journals The paracetamol concentration-effect relation in neonates

2012 ◽  
Vol 23 (1) ◽  
pp. 45-50 ◽  
Author(s):  
Karel Allegaert ◽  
Gunnar Naulaers ◽  
Sophie Vanhaesebrouck ◽  
Brian J Anderson
Keyword(s):  
Concentration Effect ◽  
Paracetamol Concentration ◽  
Effect Relation

Concentration–Effect Relation of Succinylcholine Chloride during Propofol Anesthesia

2002 ◽  
Vol 97 (5) ◽  
pp. 1082-1092 ◽  
Author(s):  
Julie J. Roy ◽  
François Donati ◽  
Daniel Boismenu ◽  
France Varin
Keyword(s):  
Rate Constant ◽  
Plasma Concentrations ◽  
Elimination Rate ◽  
Quantitative Model ◽  
Concentration Effect ◽  
Pharmacokinetic Parameters ◽  
Effect Compartment ◽  
Duration Of Action ◽  
Arterial Blood ◽  
Effect Relation

Background The pharmacokinetics and pharmacodynamics of succinylcholine were studied simultaneously in anesthetized patients to understand why the drug has a rapid onset and short duration of action. A quantitative model describing the concentration-effect relation of succinylcholine was proposed. The correlation between hydrolysis in plasma and elimination was also examined. Methods Before induction of anesthesia, blood was drawn for analysis in seven adults. Anesthesia was induced with propofol and remifentanil. Single twitch stimulation was applied at the ulnar nerve every 10 s, and the force of contraction of the adductor pollicis was measured. Arterial blood was drawn frequently after succinylcholine injection to characterize the front-end kinetics. Plasma concentrations were measured by mass spectrometry, and pharmacokinetic parameters were derived using compartmental and noncompartmental approaches. Pharmacokinetic-pharmacodynamic relations were estimated. Results The mean degradation rate constant in plasma (1.07 +/- 0.49 min(-1)) was not different from the elimination rate constant (0.97 +/- 0.30 min(-1)), and an excellent correlation (r2 = 0.94) was observed. Total body clearance derived using noncompartmental (37 +/- 7 ml x min(-1) x kg(-1)) and compartmental (37 +/- 9 ml x min(-1) x kg(-1)) approaches were similar. The plasma-effect compartment equilibration rate constant (k(eo)) was 0.058 +/- 0.026 min(-1), and the effect compartment concentration at 50% block was 734 +/- 211 ng/ml. Conclusion Succinylcholine is a low-potency drug with a very fast clearance that equilibrates relatively slowly with the effect compartment. Its disappearance is greatly accountable by a rapid hydrolysis in plasma.

Predictability of Processed Electroencephalography Effects on the Basis of Pharmacokinetic–Pharmacodynamic Modeling during Repeated Propofol Infusions in Patients with Extradural Analgesia

2001 ◽  
Vol 95 (3) ◽  
pp. 607-615 ◽  
Author(s):  
Karel Kuizenga ◽  
Johannes H. Proost ◽  
J. Mark Wierda ◽  
Cor J. Kalkman
Keyword(s):  
Steady State ◽  
Bispectral Index ◽  
Concentration Effect ◽  
Coefficient Of Determination ◽  
Pharmacodynamic Modeling ◽  
Nonparametric Models ◽  
Effect Relation ◽  
Effect Parameter ◽  
The Stability ◽  
Over Time

Background Pharmacokinetic-pharmacodynamic (PKPD) modeling can be used to characterize the concentration-effect relation of drugs. If the concentration-effect relation of a hypnotic drug is stable over time, an effect parameter derived from the processed electroencephalographic signal may be used to control the infusion for hypnosis. Therefore, the stability of the propofol concentration-electroencephalographic effect relation over time was investigated under non-steady state conditions. Methods Three propofol infusions (25 mg x kg(-1) x h(-1) for 10 min, 22 mg x kg(-1) x h(-1) for 10 min, and 12.5 mg x kg(-1) x h(-1) for 20 min) were administered to 10 patients during extradural analgesia. Each successive infusion was started immediately after the patient had regained responsiveness after termination of the preceding infusion. Electroencephalography was recorded from bilateral prefrontal to mastoid leads. Electroencephalographic amplitude in the 11- to 15-Hz band and the Bispectral Index were used as electroencephalographic effect variables. PKPD parameters were calculated with use of parametric and nonparametric models based on electroencephalographic data and arterial propofol concentrations derived during the initial infusion, and these were used to predict electroencephalographic effect during the subsequent infusions. The predictability of the electroencephalographic effects was determined by the coefficient of determination (R2) and of the -2 log likelihood of the sequential infusions. Results The direction of electroencephalographic changes in response to the infusions was reproducible. Although PKPD parameters could be estimated well during the initial infusion (median [range] parametric R2 = 0.74 [0.56-0.95] for electroencephalographic amplitude and 0.90 [0.27-0.99] for Bispectral Index), none of the modeling techniques could predict accurately the electroencephalographic effect during subsequent infusions (R2 = 0.00 [-0.31-0.46] for electroencephalographic amplitude and 0.15 [-.46-0.57] for Bispectral Index; P < 0.01). Conclusions The relation between blood propofol concentrations and the electroencephalographic effect under non-steady state conditions is not stable over time and is too complex to be modeled by any of the applied PKPD models.

Synthesis, photoluminescence and Li+ concentration effect on new reddish phosphor Li2Sr2Al(PO4)3:Sm3+ for white LEDs

2020 ◽  
Vol 120 ◽  
pp. 108152 ◽  
Author(s):  
Haidong Ju ◽  
Yongbo Liu ◽  
Xianlin Huang ◽  
Xiangqiao Feng ◽  
Baoling Wang ◽  
...  
Keyword(s):  
Concentration Effect ◽  
White Leds

Adsorption and diffusion of hydrocarbons in silicalite at very low concentration: effect of defect sites

1995 ◽  
Vol 5 (1-2) ◽  
pp. 39-52 ◽  
Author(s):  
Jeffrey R. Hufton ◽  
Douglas M. Ruthven ◽  
Ronald P. Danner
Keyword(s):  
Concentration Effect ◽  
Low Concentration ◽  
Defect Sites ◽  
And Diffusion

Copper concentration effect on physical properties of ultrasonically sprayed Cu2ZnSnS4 absorber thin films for solar cell applications

2021 ◽  
Vol 127 (2) ◽  
Author(s):  
F. Ynineb ◽  
M. Khammar ◽  
S. Guitouni ◽  
A. Hafdallah ◽  
N. Attaf ◽  
...  
Keyword(s):  
Thin Films ◽  
Solar Cell ◽  
Physical Properties ◽  
Copper Concentration ◽  
Concentration Effect

scholarly journals Advances in Cryochemistry: Mechanisms, Reactions and Applications

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 750
Author(s):  
Lu-Yan An ◽  
Zhen Dai ◽  
Bin Di ◽  
Li-Li Xu
Keyword(s):  
Low Temperature ◽  
Chemical Reactions ◽  
Common Sense ◽  
Reaction Rate ◽  
Concentration Effect ◽  
Biological Products ◽  
Freeze Concentration ◽  
New Strategy ◽  
The 1960S

It is counterintuitive that chemical reactions can be accelerated by freezing, but this amazing phenomenon was discovered as early as the 1960s. In frozen systems, the increase in reaction rate is caused by various mechanisms and the freeze concentration effect is the main reason for the observed acceleration. Some accelerated reactions have great application value in the chemistry synthesis and environmental fields; at the same time, certain reactions accelerated at low temperature during the storage of food, medicine, and biological products should cause concern. The study of reactions accelerated by freezing will overturn common sense and provide a new strategy for researchers in the chemistry field. In this review, we mainly introduce various mechanisms for accelerating reactions induced by freezing and summarize a variety of accelerated cryochemical reactions and their applications.

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