Systemic drug concentrations

The overall goal in designing sustained relea.se oral dosage forms is to provide systemic drug concentrations that remain within the therapeutic concentration range for a... 

Clearance may be calculated as the available dose divided by the area under the systemic drug concentration curve. 

In a structured modeling context, linear drug disposition is commonly thought of as a disposition governed by first-order processes. Contrary to this, the LSA approach defines linear disposition independently of the structure of the disposition processes (distribution and elimination). Linear disposition is simply a linear relationship (L) between input (7) and the measured systemic drug concentration, C. A so-called nonlinear absorption is sometimes observed in oral administrations when... 

The residence time function of a kinetic space of a linear system is the UIR of the kinetic space expressed in terms of the dose-normalized amount vs. time function with respect to drug input into the kinetic space. For example, let the kinetic space be the unchanged drug molecules in the general systemic blood circulation, and let c(f) denote the systemic drug concentration following an IV bolus injection then. 

Relatively low systemic drug concentration, avoiding toxicity. 

There are instances where the observable kinetics of elimination clearly are not due to first-order exit from a single compartment. For example, a steep curve relating drug concentration and time may indicate a two-compart-ment system in which the drug exits in two phases, one fast... 

These approaches to receptor identification and classification were, of course, pioneered by studies with peripheral systems and isolated tissues. They are more difficult to apply to the CNS, especially in in vivo experiments, where responses depend on a complex set of interacting systems and the actual drug concentration at the receptors of interest is rarely known. However, the development of in vitro preparations (acute brain slices, organotypic brain slice cultures, tissue-cultured neurons and acutely dissociated neuronal and glial cell preparations) has allowed more quantitative pharmacological techniques to be applied to the action of drugs at neurotransmitter receptors while the development of new recording methods such as patch-clamp... 

This quadratic dependence has been observed in many systems, and the dominance of lipophilicity in controlling activity reflects its importance in transport [74]. Nevertheless, the biological response (BR) of a series of compounds (which is often expressed by the inverse of the drug concentration) may also involve an electronic ( ) and/or a steric (5) contribution. Hence, QSARs have been mostly constructed using the generalized Hansch equation [337] ... 

SI (le Systeme International d UniUs) units are used in many countries to express clinical laboratory and serum drug concentration data. Instead of employing units of mass (such as micrograms), the SI system uses moles (mol) to represent the amount of a substance. A molar solution contains 1 mol (the molecular weight of the substance in grams) of the solute in 1 L of solution. The following formula is used to convert units of mass to moles (mcg/mL to pmol/L or, by substitution of terms, mg/mL to mmol/L or ng/mL to nmol/L). 

HIV phenotype A type of resistance testing for human immunodeficiency virus (HIV) in which a patient s blood sample is obtained, and the patient s HIV genes that encode for reverse transcriptase and protease are removed and placed in an HIV viral vector. This viral vector is replicated in a cell culture system with varying concentrations of antiretrovirals. A drug concentration-viral inhibition curve is developed and the concentration needed to inhibit 50% of the patient s virus is reported. This is used to predict resistance versus susceptibility. 

The term pharmacodynamics encompasses all the processes that influence the relationship between drug concentration and resulting effects. Psychotropic drugs have a wide variety of targets within neuro transmitter systems, including neurotransmitter synthesis, degradation of enzymes, storage, receptors, and specific transporter proteins. 

A mathematical model has been developed which allows the calculation of the degradation of polymeric drug delivery systems. The model has been shown to accurately simulate both the drug release and molecular weight changes in such systems. The concentration of anhydride levels affect the erosion characteristics of... 

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