Effect concentration and

Dtug interactions can cause serious problems in clinical practice especially when the affected dmg has the potential to be highly toxic. Furthermore, pharmacokinetic interactions are clinically important if the affected dmg has a narrow therapeutic range (i.e. small difference between the minimum effective concentration and the toxic concentration Fig. 1) and a steep concentration-response curve (i.e. significant alterations in pharmacological and/or adverse effects caused by small changes in blood concentration). 

A flare of acne may appear suddenly after initiation of treatment, followed by clinical clearing in 8 to 12 weeks. Once control is established, therapy should be continued at the lowest effective concentration and the longest effective interval that minimizes acne exacerbations. 

In the presence of phenytoin, the metabolism of disopyramide is increased (reducing its effective concentration) and the accumulation of its metabolites is also increased, thereby increasing the probability of anticholinergic adverse effects. Rifampin also stimulates the hepatic metaboUsm of disopyramide, reducing its plasma concentration. 

Feijtel, T.C.J. and Belanger, S.E. (1999) Predicted no-effect concentrations and risk characterization of four surfactants linear alkyl benzene sulfonate, alcohol ethoxylates, alcohol ethoxylated sulfates, and soap. Environ Toxicol Chem, 18, 2653-2663. 

In plants, biosynthesis and exudation of allelochemicals follows developmental, diurnal, and abiotic/biotic stress-dependent dynamics. Compounds from 14 different chemical classes have been linked to allelopathic interactions, including several simple phenolic acids (e.g., benzoic and hydroxycinnamic acids) and flavonoids [Rice, 1984 Macias et al., 2007]. The existence of several soil biophysical processes that can reduce the effective concentration and bioactivity of these compounds casts doubts on their actual relevance in allelopathic interactions [Olofsdotter et al., 2002]. However, there are well-documented examples of phenylpropanoid-mediated incompatible interactions among plants. Several Gramineae mediate allelopathic interactions by means of... 

Looking more at host-guest type systems, the cucurbiturils are often very efficient catalysts in cases where they simultaneously bind two guests, thus increasing effective concentration and changing a bimolecular reaction into a guas/ -unimolecular one. To take one recent example, cucurbit[6]uril (Section 6.2.4) proves to be a very efficient catalyst for the click 1,3-dipolar cycloaddition reaction of an azide with an alkyne, particularly where the substrates are suitable guests for the cavity, as in Scheme 12.20. Cucurbituril binds very effectively to ammonium ions and addition of a small amount... 

Similarly, the peaks between doses should not exceed toxic levels. Together, the minimum effective concentration and toxic level define the therapeutic window of the drug. 

Activity may be regarded as active or effective concentration, and can be related to the actual concentration by the equation... 

Alternatively, response additivity (RA) for independently acting chemicals as a mathematical null model for testing observed responses (associated with the pharmacological concept of independent joint action) and with an assumed correlation of sensitivities of 0 also often fits the data well. Again, misfits occur (e.g., when the test mixture consists of compounds with the same MOA at concentrations below the individual compound s no-effect concentrations), and when they occur, they are often in the tails of the response curves. 

State the species, effect, concentration, and exposure time to cause the effect. 

Example of relative elfect dependence on the agonist s concentration provided the agonist acts on another target as antagonist with equal semi-effective concentrations and different Hill coefficients. 

This is a term used to describe the effective concentration of a solute. In dilute solutions, solutes can be considered to behave according to ideal (thermodynamic) principles, i.e. they will have an effective concentration equivalent to the actual concentration. However, in concentrated solutions (> 0.5molL" ), the behaviour of solutes is often non-ideal, and their effective concentration (activity) will be less than the actual concentration [C]. The ratio between the effective concentration and the actual concentration is called the activity coefficient (y) where... 

All antioxidants have points of strengths and weaknesses. Therefore, certain points, such as thermal stability, effective concentration, and synergism, should be taken into consideration when selecting antioxidants for use in particular foods. Regulatory status is another factor that cannot be ignored, especially for some antioxidants that have been reported to show potential adverse health effects. Synthetic antioxidants have been tested for safety and approval for use in food at low concentrations on the basis of complex toxicity studies (10). Allowable limits for use of antioxidants vary greatly from country to country, and depend on the food product under consideration (11). 

This temporal displacement may be related to a slow biophase distribution process between plasma and effect concentrations, and the specific mechanism of drug action, such as an indirect effect or a signal transduction process. Several models that have been developed to account for this phenomenon are discussed below. 

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