Plasma concentration monitoring of most antiarrhythmic agents is of value for certain specific purposes: to determine compliance to antiarrhythmic therapy, to detect and analyze possible drug interactions, to assess the benefit to risk ratio for increasing the dose of a particular antiarrhythmic agent, to maintain a
What is drug plasma concentration?
7. “Drug concentration” is derived by collecting a blood sample at any time after drug administration and measuring the amount of a drug in a given volume of blood plasma of the sample. 8. The measured drug concentration is generally known as “plasma concentration.”
How does plasma concentration affect medication actions?
As the con- centration of drug in plasma increases, the concentration of drug in most tissues will increase proportionally. Similarly, if the plasma concentration of a drug is decreasing, the concentration in tissues will also decrease.
What are the main factors that determine plasma concentration?
Likewise, plasma levels will depend on dosage, time and route of drug administration, the bioavailability of the drug and time of blood sampling. In addition, absorption, distribution, metabolism, excretion and concurrent drug administration may profoundly affect plasma drug concentrations.
Why is pharmacokinetics and pharmacodynamics important?
Both pharmacokinetics (ADME) and pharmacodynamics are important in determining the effect that a drug regimen is likely to produce. Extrinsic factors such as environmental exposures or concomitant medications can affect the efficacy of a medication.
Why are drug concentrations more often measured in plasma rather than whole blood or serum?
Why are drug concentrations more often measured in plasma rather than whole blood or serum? Blood is composed of plasma and red blood cells (RBCs). Serum is the fluid obtained from blood after it is allowed to clot. Serum and plasma do not contain identical proteins.
How does drug concentration affect absorption?
The most common mechanism of absorption for drugs is passive diffusion. This process can be explained through the Fick law of diffusion, in which the drug molecule moves according to the concentration gradient from a higher drug concentration to a lower concentration until equilibrium is reached.
What is the relationship between drug concentration and response?
1A shows the drug concentration effect relationship. As drug concentration increases, the response rises to a maximum, at which point the receptor is saturated.
How is plasma concentration of a drug measured?
When measuring the drug concentration in plasma, a sample of whole blood is drawn from the patient (like cylinder on the left). The sample is then centrifuged to separate the RBC and plasma (like the cylinder on the right). The plasma is withdrawn and analyzed for drug concentration and the RBC is discarded.
Which technique is used to assess the drug concentration in plasma?
The concentration of drug in blood plasma can be measured via a variety of clinical chemistry techniques (e.g., immunoassays or chromatography [83] ), and these measurements can be used to parameterize pharmacokinetic models that describe the absorption, distribution, metabolism, and excretion of a therapeutic agent [
What are the parameters that describe the plasma concentration time curve and are useful in assessing the bioavailability?
Area Under the Curve(AUC):
AUC is expressed in mcg/ml * hours. It is the most important parameter in evaluating the bioavailability of a drug from its dosage form as it represents the extent of absorption.
Why is it important to understand pharmacokinetics?
Pharmacokinetics is an important field of study which provides important data on the behavior of molecules within organisms. By applying pharmacokinetic principles to preclinical trials, safer and more accurate clinical trials can be designed by scientists.
What is the significance of the plasma level time curve How does the curve relate to the pharmacologic activity of a drug?
The area under the blood (or plasma) concentration–time curve reflects the amount of a xenobiotic that has effectively reached the systemic circulation and as such is influenced both by the degree of bioavailability and by the rate at which a xenobiotic is removed from the body.
Why it is important for the nurse to know the pharmacokinetics of a drug?
Comprehending the concepts of pharmacodynamics and pharmacokinetics allows NPs to focus on how drugs alter the body from a physiological perspective, which allows them to better assess patients and suggest one medication over another.
Why plasma and serum concentration are used clinically in therapeutic drug monitoring not the whole blood?
The choice depends mostly on the policy of the hospital or the availability of the test tubes in the ward. Some of the advantages of plasma over serum are large volume, no delayed clotting, less risk of haemolysis. In addition, the sample is often suitable for both whole blood and plasma monitoring.
Is plasma concentration the same as blood concentration?
The blood to plasma ratio determines the concentration of the drug in whole blood compared to plasma and provides an indication of drug binding to erythrocytes.
Why is serum better than plasma?
Serum forms a larger percentage of blood than plasma and is most widely used in research. This is, at least in part, because it removes the unwanted red blood cells more efficiently generating more volume per unit of blood.
What is the most important characteristic of a drug to be absorbed after oral administration?
6. What is the most important characteristic of a drug to be absorbed after oral administration? Explanation: A drug should not get destroyed by either of acidic or alkaline medium. It must first pass through the biological barrier of cell membrane.
What are 4 factors that affect absorption of a drug?
These include:
- physicochemical properties (e.g. solubility)
- drug formulation (e.g. tablets, capsules, solutions)
- the route of administration (e.g. oral, buccal, sublingual, rectal, parenteral, topical, or inhaled)
- the rate of gastric emptying.
Why unionized drugs are not absorbed?
Most drugs are weak acids or bases that are present in solution as both the ionized and unionized forms. Ionized molecules are usually unable to penetrate lipid cell membranes because they are hydrophilic and poorly lipid soluble. Unionized molecules are usually lipid soluble and can diffuse across cell membranes.
What is concentration effect relationship?
Concentration–effect relationships concerns groups of patients and indicate the probability of a given response (therapeutic/toxic) at a given concentration.
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