Effect of drug concentration

The effect of drug concentration expression on epinephrine dosing errors a randomized trial. Ann 37 Intern Med 2008 148 11-14. 

It should be mentioned that certain anomalous behavior has sometimes been observed. For example, a lack, or even an inverse effect, of drug concentration on the iontophoretic flux [32,33,96] has been reported for the lipophilic, cationic drugs such as propranolol and quinine [32,33], and for peptides such as nafarelin, leuprolide, calcitonin, and octreotide [34,96,114]. This phenomenon has been associated with adsorption of the drug onto the skin and a progressive leads to a reversal of its permselective properties (see Figure 14.6) [32,33,96],... 

Fig. 3.45 Effect of drug concentration on the partition coefficients of tamoxifen (open symbols) and 4-hydroxytamoxifen (closed symbols) in DMPC bilayers (A) and in liposomes of sarcoplasmic reticulum lipids and native membranes (B). Note that the linear correlation between Kp and drug concentration is...

Fig. 9.6. Effect of drug concentration on the rate of absorption when passive diffusion is operative.

The concentrations of licensed medications may be too high, necessitating further manipulation in the form of dilution with an excipient. However, when the concentration is low, the dose volume may be too large for some children. The excipients in many liquid formulations may not be suitable for selected patient groups. For example, the propylene glycol content in amprenavir liquid formulation makes it unsuitable for children under 4 years of age. Severe delayed-onset hypersensitivity reaction was associated with formulation of amoxicillin liquid the reaction may have been caused by the exicipent (Chopra et ai, 1989). Sweeteners, dyes and other excipients may cause adverse reactions and should be identified and restricted in paediatric formulations (Kumar et ai, 1996). Some clinical studies have been directed to ascertain the effect of drug concentration and frequency of... 

Fig. 1. The effect of drug concentration, [Dt3 on per cent binding of a drug in plasma. Each curve represents a different value of K. Calculated from equation 5...

Fig. 2. The effect of drug concentration CDx] on free CDf3 bound CDbI phenylbutazone in plasma. Cat culated from equation 5 assuming n = 1, P 5.8 X 10" M and K =...

Lecomte, S., Moreau, N.J., Manfait, M., Aubard, J. and Baron, M.H. (1995) Surface-enhanced Raman spectroscopy investigation of fluoroquinolone DNA/ DNA gyrase Mg interactions. 1. Adsorption of pefloxadn on colloidal silver-effect of drug concentration, electrolytes, and pH. Biospectroscopy, 1, 423-36. 

The effects of drugs in animals are usually concentration dependent and are also often animal species and site-of-action dependent " " " thus the compounds may be present naturally in diets at low levels and produce no obvious adverse effects, either on the animal, gut microflora, meat, milk or eggs. The main purpose of the use of drugs in animal feeds is to improve the animal health and welfare and often to improve growth at minimum cost to the producer.In the case of naturally produced compounds that may occur in the feedstuff s of animals, these compounds may impair animal health and performance as well as cause im-... 

In preformulation one task is to establish the stability of the drug substance in both solid and dissolved state. In the latter case it is important, with small samples of drug substance, to assess (a) the effect of buffer type, (b) the effect of buffer concentration, (c) the effect of pH in a practical range, (d) the effect of temperature, and (e) the kinetic salt effect. 

Kempen et al. [176] synthesized a water-soluble cho-lesteryl-containing trigalactoside, Tris-Gal-Chol (I), which when incorporated in lipoproteins allows the utilization of active receptors for galactose-terminated macromolecules as a trigger for the uptake of lipoproteins. The effect of increasing concentrations of Tris-Gal-Chol on the removal of LDL and HDL from serum and their quantitative recovery in the liver is shown in Fig. 13. These data show that lipoproteins containing Tris-Gal-Chol can be used as a liver-specific drug-carrier system. 

In situ perfusion studies assess absorption as lumenal clearance or membrane permeability and provide for isolation of solute transport at the level of the intestinal tissue. Controlled input of drug concentration, perfusion pH, osmolality, composition, and flow rate combined with intestinal region selection allow for separation of aqueous resistance and water transport effects on solute tissue permeation. This system provides for solute sampling from GI lumenal and plasma (mesenteric and systemic) compartments. A sensitive assay can separate metabolic from transport contributions. 

E. K. Anderberg, M. Bisrat, C. Nystrom. Physicochemical aspects of drug release. VII. The effect of surfactant concentration and drug particle size on solubility and dissolution rate of felodipine, a sparingly soluble drug. Int. I. Pharm. 1988, 47, 67-77. 

Davies, DS and BNC Prichard, Eds., Biological Effects of Drugs in Relation to their Plasma Concentration , New York, McMillan, 1973. 

A fundamental experiment that characterizes the function of an expressed receptor is to determine the concentration-effect relationship. By measuring the response of the receptor population to a range of drug concentrations, the potency of a drug can be determined (e.g., O Figure 14-2). In these experiments, an... 

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